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Drug Interactions between measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and Norco

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

measles virus vaccine rubella virus vaccine

Applies to: measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine

ADJUST DOSING INTERVAL: If multiple live, attenuated parenteral viral or bacterial vaccines are not given on the same day, but are administered within 28 days of each other, the immune response to the second live parenteral vaccine may be diminished by the immune response to the first. The exact mechanism of this interaction is unknown, but may involve competition for cellular receptors, competition for molecular substrates required for replication, and/or induction of inhibitory host proteins like interferon. Clinical data are limited and sometimes conflicting. One randomized clinical trial in Brazil was conducted in 12-month-old children (n=1769) receiving routine vaccinations. Volunteers were randomized to receive simultaneous yellow fever (YF) and measles, mumps, rubella (MMR) vaccines or to receive YF 30 days after the MMR vaccine. Subjects who received both vaccines simultaneously had lower seroconversion rates for rubella, YF, and mumps than those vaccinated 30 days apart (90% vs. 97%, 70% vs. 87%, and 62% vs. 71%, respectively). Seroconversion rates for measles were unaffected (>98% in both groups). Geometric mean titers (GMT) for rubella and YF were approximately three times higher in those who were vaccinated 30 days apart. However, a different randomized, non-inferiority trial in healthy one-year-old children in Argentina (n=738), which evaluated coadministration of MMR and YF vaccines compared to MMR followed by the YF vaccine 28 to 35 days later, or YF followed by the MMR vaccine 28 to 35 days later, reported that effective seroconversion was achieved when the two vaccines were administered concurrently. This study did note that antibody levels for rubella and YF were significantly lower following co-administration. A separate study conducted in two U.S. health maintenance organizations found that the risk for varicella vaccine failure (defined as varicella disease in a vaccinated individual) was three times higher in those who received the varicella vaccine within 28 days of the MMR vaccine, when compared to those who received the varicella vaccine more than 28 days after MMR vaccination. Clinical data are not available for all possible live vaccine combinations in all age groups.

MANAGEMENT: The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices generally recommends that doses of live, attenuated parenteral viral or bacterial vaccines that are not administered simultaneously (using different injection sites and separate needles and syringes for injectable products not formulated as combinations) should be separated by an interval of at least 28 days. If the live vaccines involved are separated by less than 4 weeks, the second vaccine administered should not be counted and the dose should be repeated at least 4 weeks later. Oral vaccines (e.g., Ty21a typhoid vaccine and rotavirus) can be administered simultaneously with or at any interval before or after other live vaccines if indicated. The United Kingdom's Green Book recommends always separating the YF and MMR vaccines by at least 4 weeks, unless rapid protection is required in which case they advise considering an additional dose of the MMR vaccine. Additionally, the Canadian Immunization Guide recommends avoiding simultaneous administration of a first-generation smallpox vaccine with a varicella-containing vaccine; suggesting that if both are needed, the varicella-containing vaccine should be given at least 4 weeks before or after the first-generation smallpox vaccine. Current local immunization guidelines and prescribing information for individual vaccines should be consulted for specific recommendations.

References (9)
  1. Public Health Agency of Canada (2025) Timing of vaccine administration: Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-10-timing-vaccine-administration.html
  2. US Centers for Disease Control and Prevention (CDC) (2025) Timing and spacing of immunobiologics. https://www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html
  3. Staples JE, O'Laughlin K (2025) Yellow Fever https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html#prevent
  4. UK Health Security Agency (2025) Contraindications and special considerations: the green book, chapter 6. https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6
  5. UK Health Security Agency (2025) Measles: the green book, chapter 21. https://www.gov.uk/government/publications/measles-the-green-book-chapter-21
  6. Australian Government. Department of Health and Aged Care (2025) Preparing for vaccination. https://immunisationhandbook.health.gov.au/contents/vaccination-procedures/preparing-for-vaccination
  7. Nascimento Silva JR, Camacho LA, Siqueira MM, et al. (2011) "Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella." Vaccine, 29, p. 6327-34
  8. Boikos C, Papenburg J, Martineau C, et al. (2017) "Viral interference and the live-attenuated intranasal influenza vaccine: results from a pediatric cohort with cystic fibrosis." Hum Vacc Immunother, 13, p. 1254-60
  9. Vizzotti C, Harris JB, Aquino A, et al. (2025) Immune response to co-administration of measles, mumps, and rubella (MMR) and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina. https://pmc.ncbi.nlm.nih.gov/articles/PMC10021967/
Moderate

measles virus vaccine mumps virus vaccine

Applies to: measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine

ADJUST DOSING INTERVAL: If multiple live, attenuated parenteral viral or bacterial vaccines are not given on the same day, but are administered within 28 days of each other, the immune response to the second live parenteral vaccine may be diminished by the immune response to the first. The exact mechanism of this interaction is unknown, but may involve competition for cellular receptors, competition for molecular substrates required for replication, and/or induction of inhibitory host proteins like interferon. Clinical data are limited and sometimes conflicting. One randomized clinical trial in Brazil was conducted in 12-month-old children (n=1769) receiving routine vaccinations. Volunteers were randomized to receive simultaneous yellow fever (YF) and measles, mumps, rubella (MMR) vaccines or to receive YF 30 days after the MMR vaccine. Subjects who received both vaccines simultaneously had lower seroconversion rates for rubella, YF, and mumps than those vaccinated 30 days apart (90% vs. 97%, 70% vs. 87%, and 62% vs. 71%, respectively). Seroconversion rates for measles were unaffected (>98% in both groups). Geometric mean titers (GMT) for rubella and YF were approximately three times higher in those who were vaccinated 30 days apart. However, a different randomized, non-inferiority trial in healthy one-year-old children in Argentina (n=738), which evaluated coadministration of MMR and YF vaccines compared to MMR followed by the YF vaccine 28 to 35 days later, or YF followed by the MMR vaccine 28 to 35 days later, reported that effective seroconversion was achieved when the two vaccines were administered concurrently. This study did note that antibody levels for rubella and YF were significantly lower following co-administration. A separate study conducted in two U.S. health maintenance organizations found that the risk for varicella vaccine failure (defined as varicella disease in a vaccinated individual) was three times higher in those who received the varicella vaccine within 28 days of the MMR vaccine, when compared to those who received the varicella vaccine more than 28 days after MMR vaccination. Clinical data are not available for all possible live vaccine combinations in all age groups.

MANAGEMENT: The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices generally recommends that doses of live, attenuated parenteral viral or bacterial vaccines that are not administered simultaneously (using different injection sites and separate needles and syringes for injectable products not formulated as combinations) should be separated by an interval of at least 28 days. If the live vaccines involved are separated by less than 4 weeks, the second vaccine administered should not be counted and the dose should be repeated at least 4 weeks later. Oral vaccines (e.g., Ty21a typhoid vaccine and rotavirus) can be administered simultaneously with or at any interval before or after other live vaccines if indicated. The United Kingdom's Green Book recommends always separating the YF and MMR vaccines by at least 4 weeks, unless rapid protection is required in which case they advise considering an additional dose of the MMR vaccine. Additionally, the Canadian Immunization Guide recommends avoiding simultaneous administration of a first-generation smallpox vaccine with a varicella-containing vaccine; suggesting that if both are needed, the varicella-containing vaccine should be given at least 4 weeks before or after the first-generation smallpox vaccine. Current local immunization guidelines and prescribing information for individual vaccines should be consulted for specific recommendations.

References (9)
  1. Public Health Agency of Canada (2025) Timing of vaccine administration: Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-10-timing-vaccine-administration.html
  2. US Centers for Disease Control and Prevention (CDC) (2025) Timing and spacing of immunobiologics. https://www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html
  3. Staples JE, O'Laughlin K (2025) Yellow Fever https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html#prevent
  4. UK Health Security Agency (2025) Contraindications and special considerations: the green book, chapter 6. https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6
  5. UK Health Security Agency (2025) Measles: the green book, chapter 21. https://www.gov.uk/government/publications/measles-the-green-book-chapter-21
  6. Australian Government. Department of Health and Aged Care (2025) Preparing for vaccination. https://immunisationhandbook.health.gov.au/contents/vaccination-procedures/preparing-for-vaccination
  7. Nascimento Silva JR, Camacho LA, Siqueira MM, et al. (2011) "Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella." Vaccine, 29, p. 6327-34
  8. Boikos C, Papenburg J, Martineau C, et al. (2017) "Viral interference and the live-attenuated intranasal influenza vaccine: results from a pediatric cohort with cystic fibrosis." Hum Vacc Immunother, 13, p. 1254-60
  9. Vizzotti C, Harris JB, Aquino A, et al. (2025) Immune response to co-administration of measles, mumps, and rubella (MMR) and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina. https://pmc.ncbi.nlm.nih.gov/articles/PMC10021967/
Moderate

measles virus vaccine varicella virus vaccine

Applies to: measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine

ADJUST DOSING INTERVAL: If multiple live, attenuated parenteral viral or bacterial vaccines are not given on the same day, but are administered within 28 days of each other, the immune response to the second live parenteral vaccine may be diminished by the immune response to the first. The exact mechanism of this interaction is unknown, but may involve competition for cellular receptors, competition for molecular substrates required for replication, and/or induction of inhibitory host proteins like interferon. Clinical data are limited and sometimes conflicting. One randomized clinical trial in Brazil was conducted in 12-month-old children (n=1769) receiving routine vaccinations. Volunteers were randomized to receive simultaneous yellow fever (YF) and measles, mumps, rubella (MMR) vaccines or to receive YF 30 days after the MMR vaccine. Subjects who received both vaccines simultaneously had lower seroconversion rates for rubella, YF, and mumps than those vaccinated 30 days apart (90% vs. 97%, 70% vs. 87%, and 62% vs. 71%, respectively). Seroconversion rates for measles were unaffected (>98% in both groups). Geometric mean titers (GMT) for rubella and YF were approximately three times higher in those who were vaccinated 30 days apart. However, a different randomized, non-inferiority trial in healthy one-year-old children in Argentina (n=738), which evaluated coadministration of MMR and YF vaccines compared to MMR followed by the YF vaccine 28 to 35 days later, or YF followed by the MMR vaccine 28 to 35 days later, reported that effective seroconversion was achieved when the two vaccines were administered concurrently. This study did note that antibody levels for rubella and YF were significantly lower following co-administration. A separate study conducted in two U.S. health maintenance organizations found that the risk for varicella vaccine failure (defined as varicella disease in a vaccinated individual) was three times higher in those who received the varicella vaccine within 28 days of the MMR vaccine, when compared to those who received the varicella vaccine more than 28 days after MMR vaccination. Clinical data are not available for all possible live vaccine combinations in all age groups.

MANAGEMENT: The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices generally recommends that doses of live, attenuated parenteral viral or bacterial vaccines that are not administered simultaneously (using different injection sites and separate needles and syringes for injectable products not formulated as combinations) should be separated by an interval of at least 28 days. If the live vaccines involved are separated by less than 4 weeks, the second vaccine administered should not be counted and the dose should be repeated at least 4 weeks later. Oral vaccines (e.g., Ty21a typhoid vaccine and rotavirus) can be administered simultaneously with or at any interval before or after other live vaccines if indicated. The United Kingdom's Green Book recommends always separating the YF and MMR vaccines by at least 4 weeks, unless rapid protection is required in which case they advise considering an additional dose of the MMR vaccine. Additionally, the Canadian Immunization Guide recommends avoiding simultaneous administration of a first-generation smallpox vaccine with a varicella-containing vaccine; suggesting that if both are needed, the varicella-containing vaccine should be given at least 4 weeks before or after the first-generation smallpox vaccine. Current local immunization guidelines and prescribing information for individual vaccines should be consulted for specific recommendations.

References (9)
  1. Public Health Agency of Canada (2025) Timing of vaccine administration: Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-10-timing-vaccine-administration.html
  2. US Centers for Disease Control and Prevention (CDC) (2025) Timing and spacing of immunobiologics. https://www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html
  3. Staples JE, O'Laughlin K (2025) Yellow Fever https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html#prevent
  4. UK Health Security Agency (2025) Contraindications and special considerations: the green book, chapter 6. https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6
  5. UK Health Security Agency (2025) Measles: the green book, chapter 21. https://www.gov.uk/government/publications/measles-the-green-book-chapter-21
  6. Australian Government. Department of Health and Aged Care (2025) Preparing for vaccination. https://immunisationhandbook.health.gov.au/contents/vaccination-procedures/preparing-for-vaccination
  7. Nascimento Silva JR, Camacho LA, Siqueira MM, et al. (2011) "Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella." Vaccine, 29, p. 6327-34
  8. Boikos C, Papenburg J, Martineau C, et al. (2017) "Viral interference and the live-attenuated intranasal influenza vaccine: results from a pediatric cohort with cystic fibrosis." Hum Vacc Immunother, 13, p. 1254-60
  9. Vizzotti C, Harris JB, Aquino A, et al. (2025) Immune response to co-administration of measles, mumps, and rubella (MMR) and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina. https://pmc.ncbi.nlm.nih.gov/articles/PMC10021967/
Moderate

rubella virus vaccine mumps virus vaccine

Applies to: measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine

ADJUST DOSING INTERVAL: If multiple live, attenuated parenteral viral or bacterial vaccines are not given on the same day, but are administered within 28 days of each other, the immune response to the second live parenteral vaccine may be diminished by the immune response to the first. The exact mechanism of this interaction is unknown, but may involve competition for cellular receptors, competition for molecular substrates required for replication, and/or induction of inhibitory host proteins like interferon. Clinical data are limited and sometimes conflicting. One randomized clinical trial in Brazil was conducted in 12-month-old children (n=1769) receiving routine vaccinations. Volunteers were randomized to receive simultaneous yellow fever (YF) and measles, mumps, rubella (MMR) vaccines or to receive YF 30 days after the MMR vaccine. Subjects who received both vaccines simultaneously had lower seroconversion rates for rubella, YF, and mumps than those vaccinated 30 days apart (90% vs. 97%, 70% vs. 87%, and 62% vs. 71%, respectively). Seroconversion rates for measles were unaffected (>98% in both groups). Geometric mean titers (GMT) for rubella and YF were approximately three times higher in those who were vaccinated 30 days apart. However, a different randomized, non-inferiority trial in healthy one-year-old children in Argentina (n=738), which evaluated coadministration of MMR and YF vaccines compared to MMR followed by the YF vaccine 28 to 35 days later, or YF followed by the MMR vaccine 28 to 35 days later, reported that effective seroconversion was achieved when the two vaccines were administered concurrently. This study did note that antibody levels for rubella and YF were significantly lower following co-administration. A separate study conducted in two U.S. health maintenance organizations found that the risk for varicella vaccine failure (defined as varicella disease in a vaccinated individual) was three times higher in those who received the varicella vaccine within 28 days of the MMR vaccine, when compared to those who received the varicella vaccine more than 28 days after MMR vaccination. Clinical data are not available for all possible live vaccine combinations in all age groups.

MANAGEMENT: The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices generally recommends that doses of live, attenuated parenteral viral or bacterial vaccines that are not administered simultaneously (using different injection sites and separate needles and syringes for injectable products not formulated as combinations) should be separated by an interval of at least 28 days. If the live vaccines involved are separated by less than 4 weeks, the second vaccine administered should not be counted and the dose should be repeated at least 4 weeks later. Oral vaccines (e.g., Ty21a typhoid vaccine and rotavirus) can be administered simultaneously with or at any interval before or after other live vaccines if indicated. The United Kingdom's Green Book recommends always separating the YF and MMR vaccines by at least 4 weeks, unless rapid protection is required in which case they advise considering an additional dose of the MMR vaccine. Additionally, the Canadian Immunization Guide recommends avoiding simultaneous administration of a first-generation smallpox vaccine with a varicella-containing vaccine; suggesting that if both are needed, the varicella-containing vaccine should be given at least 4 weeks before or after the first-generation smallpox vaccine. Current local immunization guidelines and prescribing information for individual vaccines should be consulted for specific recommendations.

References (9)
  1. Public Health Agency of Canada (2025) Timing of vaccine administration: Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-10-timing-vaccine-administration.html
  2. US Centers for Disease Control and Prevention (CDC) (2025) Timing and spacing of immunobiologics. https://www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html
  3. Staples JE, O'Laughlin K (2025) Yellow Fever https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html#prevent
  4. UK Health Security Agency (2025) Contraindications and special considerations: the green book, chapter 6. https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6
  5. UK Health Security Agency (2025) Measles: the green book, chapter 21. https://www.gov.uk/government/publications/measles-the-green-book-chapter-21
  6. Australian Government. Department of Health and Aged Care (2025) Preparing for vaccination. https://immunisationhandbook.health.gov.au/contents/vaccination-procedures/preparing-for-vaccination
  7. Nascimento Silva JR, Camacho LA, Siqueira MM, et al. (2011) "Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella." Vaccine, 29, p. 6327-34
  8. Boikos C, Papenburg J, Martineau C, et al. (2017) "Viral interference and the live-attenuated intranasal influenza vaccine: results from a pediatric cohort with cystic fibrosis." Hum Vacc Immunother, 13, p. 1254-60
  9. Vizzotti C, Harris JB, Aquino A, et al. (2025) Immune response to co-administration of measles, mumps, and rubella (MMR) and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina. https://pmc.ncbi.nlm.nih.gov/articles/PMC10021967/
Moderate

rubella virus vaccine varicella virus vaccine

Applies to: measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine

ADJUST DOSING INTERVAL: If multiple live, attenuated parenteral viral or bacterial vaccines are not given on the same day, but are administered within 28 days of each other, the immune response to the second live parenteral vaccine may be diminished by the immune response to the first. The exact mechanism of this interaction is unknown, but may involve competition for cellular receptors, competition for molecular substrates required for replication, and/or induction of inhibitory host proteins like interferon. Clinical data are limited and sometimes conflicting. One randomized clinical trial in Brazil was conducted in 12-month-old children (n=1769) receiving routine vaccinations. Volunteers were randomized to receive simultaneous yellow fever (YF) and measles, mumps, rubella (MMR) vaccines or to receive YF 30 days after the MMR vaccine. Subjects who received both vaccines simultaneously had lower seroconversion rates for rubella, YF, and mumps than those vaccinated 30 days apart (90% vs. 97%, 70% vs. 87%, and 62% vs. 71%, respectively). Seroconversion rates for measles were unaffected (>98% in both groups). Geometric mean titers (GMT) for rubella and YF were approximately three times higher in those who were vaccinated 30 days apart. However, a different randomized, non-inferiority trial in healthy one-year-old children in Argentina (n=738), which evaluated coadministration of MMR and YF vaccines compared to MMR followed by the YF vaccine 28 to 35 days later, or YF followed by the MMR vaccine 28 to 35 days later, reported that effective seroconversion was achieved when the two vaccines were administered concurrently. This study did note that antibody levels for rubella and YF were significantly lower following co-administration. A separate study conducted in two U.S. health maintenance organizations found that the risk for varicella vaccine failure (defined as varicella disease in a vaccinated individual) was three times higher in those who received the varicella vaccine within 28 days of the MMR vaccine, when compared to those who received the varicella vaccine more than 28 days after MMR vaccination. Clinical data are not available for all possible live vaccine combinations in all age groups.

MANAGEMENT: The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices generally recommends that doses of live, attenuated parenteral viral or bacterial vaccines that are not administered simultaneously (using different injection sites and separate needles and syringes for injectable products not formulated as combinations) should be separated by an interval of at least 28 days. If the live vaccines involved are separated by less than 4 weeks, the second vaccine administered should not be counted and the dose should be repeated at least 4 weeks later. Oral vaccines (e.g., Ty21a typhoid vaccine and rotavirus) can be administered simultaneously with or at any interval before or after other live vaccines if indicated. The United Kingdom's Green Book recommends always separating the YF and MMR vaccines by at least 4 weeks, unless rapid protection is required in which case they advise considering an additional dose of the MMR vaccine. Additionally, the Canadian Immunization Guide recommends avoiding simultaneous administration of a first-generation smallpox vaccine with a varicella-containing vaccine; suggesting that if both are needed, the varicella-containing vaccine should be given at least 4 weeks before or after the first-generation smallpox vaccine. Current local immunization guidelines and prescribing information for individual vaccines should be consulted for specific recommendations.

References (9)
  1. Public Health Agency of Canada (2025) Timing of vaccine administration: Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-10-timing-vaccine-administration.html
  2. US Centers for Disease Control and Prevention (CDC) (2025) Timing and spacing of immunobiologics. https://www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html
  3. Staples JE, O'Laughlin K (2025) Yellow Fever https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html#prevent
  4. UK Health Security Agency (2025) Contraindications and special considerations: the green book, chapter 6. https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6
  5. UK Health Security Agency (2025) Measles: the green book, chapter 21. https://www.gov.uk/government/publications/measles-the-green-book-chapter-21
  6. Australian Government. Department of Health and Aged Care (2025) Preparing for vaccination. https://immunisationhandbook.health.gov.au/contents/vaccination-procedures/preparing-for-vaccination
  7. Nascimento Silva JR, Camacho LA, Siqueira MM, et al. (2011) "Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella." Vaccine, 29, p. 6327-34
  8. Boikos C, Papenburg J, Martineau C, et al. (2017) "Viral interference and the live-attenuated intranasal influenza vaccine: results from a pediatric cohort with cystic fibrosis." Hum Vacc Immunother, 13, p. 1254-60
  9. Vizzotti C, Harris JB, Aquino A, et al. (2025) Immune response to co-administration of measles, mumps, and rubella (MMR) and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina. https://pmc.ncbi.nlm.nih.gov/articles/PMC10021967/
Moderate

mumps virus vaccine varicella virus vaccine

Applies to: measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine and measles virus vaccine / mumps virus vaccine / rubella virus vaccine / varicella virus vaccine

ADJUST DOSING INTERVAL: If multiple live, attenuated parenteral viral or bacterial vaccines are not given on the same day, but are administered within 28 days of each other, the immune response to the second live parenteral vaccine may be diminished by the immune response to the first. The exact mechanism of this interaction is unknown, but may involve competition for cellular receptors, competition for molecular substrates required for replication, and/or induction of inhibitory host proteins like interferon. Clinical data are limited and sometimes conflicting. One randomized clinical trial in Brazil was conducted in 12-month-old children (n=1769) receiving routine vaccinations. Volunteers were randomized to receive simultaneous yellow fever (YF) and measles, mumps, rubella (MMR) vaccines or to receive YF 30 days after the MMR vaccine. Subjects who received both vaccines simultaneously had lower seroconversion rates for rubella, YF, and mumps than those vaccinated 30 days apart (90% vs. 97%, 70% vs. 87%, and 62% vs. 71%, respectively). Seroconversion rates for measles were unaffected (>98% in both groups). Geometric mean titers (GMT) for rubella and YF were approximately three times higher in those who were vaccinated 30 days apart. However, a different randomized, non-inferiority trial in healthy one-year-old children in Argentina (n=738), which evaluated coadministration of MMR and YF vaccines compared to MMR followed by the YF vaccine 28 to 35 days later, or YF followed by the MMR vaccine 28 to 35 days later, reported that effective seroconversion was achieved when the two vaccines were administered concurrently. This study did note that antibody levels for rubella and YF were significantly lower following co-administration. A separate study conducted in two U.S. health maintenance organizations found that the risk for varicella vaccine failure (defined as varicella disease in a vaccinated individual) was three times higher in those who received the varicella vaccine within 28 days of the MMR vaccine, when compared to those who received the varicella vaccine more than 28 days after MMR vaccination. Clinical data are not available for all possible live vaccine combinations in all age groups.

MANAGEMENT: The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices generally recommends that doses of live, attenuated parenteral viral or bacterial vaccines that are not administered simultaneously (using different injection sites and separate needles and syringes for injectable products not formulated as combinations) should be separated by an interval of at least 28 days. If the live vaccines involved are separated by less than 4 weeks, the second vaccine administered should not be counted and the dose should be repeated at least 4 weeks later. Oral vaccines (e.g., Ty21a typhoid vaccine and rotavirus) can be administered simultaneously with or at any interval before or after other live vaccines if indicated. The United Kingdom's Green Book recommends always separating the YF and MMR vaccines by at least 4 weeks, unless rapid protection is required in which case they advise considering an additional dose of the MMR vaccine. Additionally, the Canadian Immunization Guide recommends avoiding simultaneous administration of a first-generation smallpox vaccine with a varicella-containing vaccine; suggesting that if both are needed, the varicella-containing vaccine should be given at least 4 weeks before or after the first-generation smallpox vaccine. Current local immunization guidelines and prescribing information for individual vaccines should be consulted for specific recommendations.

References (9)
  1. Public Health Agency of Canada (2025) Timing of vaccine administration: Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-10-timing-vaccine-administration.html
  2. US Centers for Disease Control and Prevention (CDC) (2025) Timing and spacing of immunobiologics. https://www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html
  3. Staples JE, O'Laughlin K (2025) Yellow Fever https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html#prevent
  4. UK Health Security Agency (2025) Contraindications and special considerations: the green book, chapter 6. https://www.gov.uk/government/publications/contraindications-and-special-considerations-the-green-book-chapter-6
  5. UK Health Security Agency (2025) Measles: the green book, chapter 21. https://www.gov.uk/government/publications/measles-the-green-book-chapter-21
  6. Australian Government. Department of Health and Aged Care (2025) Preparing for vaccination. https://immunisationhandbook.health.gov.au/contents/vaccination-procedures/preparing-for-vaccination
  7. Nascimento Silva JR, Camacho LA, Siqueira MM, et al. (2011) "Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella." Vaccine, 29, p. 6327-34
  8. Boikos C, Papenburg J, Martineau C, et al. (2017) "Viral interference and the live-attenuated intranasal influenza vaccine: results from a pediatric cohort with cystic fibrosis." Hum Vacc Immunother, 13, p. 1254-60
  9. Vizzotti C, Harris JB, Aquino A, et al. (2025) Immune response to co-administration of measles, mumps, and rubella (MMR) and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina. https://pmc.ncbi.nlm.nih.gov/articles/PMC10021967/

Drug and food interactions

Major

HYDROcodone food

Applies to: Norco (acetaminophen / hydrocodone)

GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics including hydrocodone. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

GENERALLY AVOID: Consumption of alcohol while taking some sustained-release formulations of hydrocodone may cause rapid release of the drug, resulting in high systemic levels of hydrocodone that may be potentially lethal. Alcohol apparently can disrupt the release mechanism of some sustained-release formulations. In study subjects, the rate of absorption of hydrocodone from an extended-release formulation was found to be affected by coadministration with 40% alcohol in the fasted state, as demonstrated by an average 2.4-fold (up to 3.9-fold in one subject) increase in hydrocodone peak plasma concentration and a decrease in the time to peak concentration. Alcohol also increased the extent of absorption by an average of 1.2-fold (up to 1.7-fold in one subject).

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of hydrocodone. The proposed mechanism is inhibition of CYP450 3A4-mediated metabolism of hydrocodone by certain compounds present in grapefruit. Increased hydrocodone concentrations could conceivably increase or prolong adverse drug effects and may cause potentially fatal respiratory depression.

MANAGEMENT: Patients taking sustained-release formulations of hydrocodone should not consume alcohol or use medications that contain alcohol. In general, potent narcotics such as hydrocodone should not be combined with alcohol. Patients should also avoid consumption of grapefruit or grapefruit juice during treatment with hydrocodone.

References (1)
  1. (2013) "Product Information. Zohydro ER (hydrocodone)." Zogenix, Inc
Major

acetaminophen food

Applies to: Norco (acetaminophen / hydrocodone)

GENERALLY AVOID: Chronic, excessive consumption of alcohol may increase the risk of acetaminophen-induced hepatotoxicity, which has included rare cases of fatal hepatitis and frank hepatic failure requiring liver transplantation. The proposed mechanism is induction of hepatic microsomal enzymes during chronic alcohol use, which may result in accelerated metabolism of acetaminophen and increased production of potentially hepatotoxic metabolites.

MANAGEMENT: In general, chronic alcoholics should avoid regular or excessive use of acetaminophen. Alternative analgesic/antipyretic therapy may be appropriate in patients who consume three or more alcoholic drinks per day. However, if acetaminophen is used, these patients should be cautioned not to exceed the recommended dosage (maximum 4 g/day in adults and children 12 years of age or older).

References (12)
  1. Kaysen GA, Pond SM, Roper MH, Menke DJ, Marrama MA (1985) "Combined hepatic and renal injury in alcoholics during therapeutic use of acetaminophen." Arch Intern Med, 145, p. 2019-23
  2. O'Dell JR, Zetterman RK, Burnett DA (1986) "Centrilobular hepatic fibrosis following acetaminophen-induced hepatic necrosis in an alcoholic." JAMA, 255, p. 2636-7
  3. Seeff LB, Cuccherini BA, Zimmerman HJ, Adler E, Benjamin SB (1986) "Acetaminophen hepatotoxicity in alcoholics." Ann Intern Med, 104, p. 399-404
  4. Thummel KE, Slattery JT, Nelson SD (1988) "Mechanism by which ethanol diminishes the hepatotoxicity of acetaminophen." J Pharmacol Exp Ther, 245, p. 129-36
  5. McClain CJ, Kromhout JP, Peterson FJ, Holtzman JL (1980) "Potentiation of acetaminophen hepatotoxicity by alcohol." JAMA, 244, p. 251-3
  6. Kartsonis A, Reddy KR, Schiff ER (1986) "Alcohol, acetaminophen, and hepatic necrosis." Ann Intern Med, 105, p. 138-9
  7. Prescott LF, Critchley JA (1983) "Drug interactions affecting analgesic toxicity." Am J Med, 75, p. 113-6
  8. (2002) "Product Information. Tylenol (acetaminophen)." McNeil Pharmaceutical
  9. Whitcomb DC, Block GD (1994) "Association of acetaminopphen hepatotoxicity with fasting and ethanol use." JAMA, 272, p. 1845-50
  10. Bonkovsky HL (1995) "Acetaminophen hepatotoxicity, fasting, and ethanol." JAMA, 274, p. 301
  11. Nelson EB, Temple AR (1995) "Acetaminophen hepatotoxicity, fasting, and ethanol." JAMA, 274, p. 301
  12. Zimmerman HJ, Maddrey WC (1995) "Acetaminophen (paracetamol) hepatotoxicity with regular intake of alcohol: analysis of instances of therapeutic misadventure." Hepatology, 22, p. 767-73
Moderate

acetaminophen food

Applies to: Norco (acetaminophen / hydrocodone)

MONITOR: Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.

MANAGEMENT: Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.

References (4)
  1. (2024) "Product Information. Cytisine (cytisinicline)." Consilient Health Ltd
  2. jeong sh, Newcombe D, sheridan j, Tingle M (2015) "Pharmacokinetics of cytisine, an a4 b2 nicotinic receptor partial agonist, in healthy smokers following a single dose." Drug Test Anal, 7, p. 475-82
  3. Vaughan DP, Beckett AH, Robbie DS (1976) "The influence of smoking on the intersubject variation in pentazocine elimination." Br J Clin Pharmacol, 3, p. 279-83
  4. Zevin S, Benowitz NL (1999) "Drug interactions with tobacco smoking: an update" Clin Pharmacokinet, 36, p. 425-38

Therapeutic duplication warnings

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Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.


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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.