Drug Interactions between cimetidine and levothyroxine
This report displays the potential drug interactions for the following 2 drugs:
- cimetidine
- levothyroxine
Interactions between your drugs
cimetidine levothyroxine
Applies to: cimetidine and levothyroxine
Consumer information for this interaction is not currently available.
ADJUST DOSING INTERVAL: Concurrent administration of cimetidine may decrease the oral bioavailability of levothyroxine. Pharmacologic effects of levothyroxine may be reduced. The mechanism of this interaction is not fully understood but may be related to decreased gastric acidity, which may reduce levothyroxine absorption. However, ranitidine, famotidine and the proton pump inhibitors pantoprazole and lansoprazole did not affect the absorption of levothyroxine. It is not known whether this interaction occurs with other thyroid hormone preparations.
MANAGEMENT: Some manufacturers of levothyroxine recommend separating the times of administration of levothyroxine and cimetidine by at least 4 hours. Monitoring of serum TSH levels is also recommended.
Drug and food interactions
levothyroxine food
Applies to: levothyroxine
The timing of meals relative to your oral levothyroxine dose can affect the absorption of the medication. Therefore, levothyroxine should be taken on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in blood levels, which may alter its effects. In addition, absorption of levothyroxine may be decreased and/or delayed by foods such as soybean flour, cotton seed meal, walnuts, dietary fiber, calcium, calcium fortified juices and grapefruit or grapefruit juice. These foods should be avoided within several hours of dosing if possible. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.
levothyroxine food
Applies to: levothyroxine
Using multivitamin with minerals together with levothyroxine may decrease the effects of levothyroxine. You should separate the administration of levothyroxine and multivitamin with minerals by at least 4 hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.
cimetidine food
Applies to: cimetidine
Information for this minor interaction is available on the professional version.
cimetidine food
Applies to: cimetidine
Information for this minor interaction is available on the professional version.
cimetidine food
Applies to: cimetidine
Information for this minor interaction is available on the professional version.
Therapeutic duplication warnings
No warnings were found for your selected drugs.
Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.
See also
Drug Interaction Classification
Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
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. | |
No interaction information available. |
Further information
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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