Skip to Content

Drug Interaction Report

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

  • Dvorah (acetaminophen / caffeine / dihydrocodeine)
    The interactions information for this drug may not be up-to-date. More...
  • efavirenz

Edit list (add/remove drugs)

Interactions between your drugs


dihydrocodeine efavirenz

Applies to: Dvorah (acetaminophen / caffeine / dihydrocodeine), efavirenz

Consumer information for this interaction is not currently available.

MONITOR: Coadministration of codeine with potent or moderate CYP450 3A4 inducers may result in lower codeine plasma concentrations, higher levels of the inactive metabolite norcodeine, and less metabolism via CYP450 2D6, resulting in lower morphine levels. This interaction may lead to reduced codeine efficacy and potentially initiate the onset of withdrawal symptoms in patients who are physically dependent. In addition, patients may be at an increased risk of CNS and/or respiratory-depressant effects from increased levels of codeine once concomitant therapy with the CYP450 3A4 inducer is ceased. This is particularly worrisome if the CYP450 3A4 inducer also possesses CNS- and/or respiratory-depressant effects. This interaction has also been reported with dihydrocodeine.

MANAGEMENT: The potential loss of efficacy of codeine or dihydrocodeine and onset of opioid withdrawal symptoms should be considered when used in combination with a potent or moderate CYP450 3A4 inducer. Alternative agents with no or minimal CYP450 3A4 induction potential are recommended whenever possible. Some manufacturers of products containing codeine advise against the concomitant use of codeine with CYP450 3A4 inducers. If concomitant use is considered necessary, caution and close clinical and laboratory monitoring are recommended. Dosage adjustments may also be required whenever a CYP450 3A4 inducer is added to or withdrawn from therapy. Following discontinuation of a CYP450 3A4 inducer, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression.


acetaminophen efavirenz

Applies to: Dvorah (acetaminophen / caffeine / dihydrocodeine), efavirenz

Efavirenz may cause liver problems, and using it with other medications that can also affect the liver such as acetaminophen may increase that risk. You should avoid or limit the use of alcohol while being treated with these medications. Call your doctor immediately if you have fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, abdominal pain, dark colored urine, light colored stools, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. Talk to your doctor or pharmacist if you have any questions or concerns. 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.

Switch to professional interaction data

Drug and food interactions


efavirenz food

Applies to: efavirenz

Taking efavirenz with food increases the amount of medicine in your body, which may increase the frequency of side effects. You should take efavirenz once a day on an empty stomach, preferably at bedtime. Taking it at bedtime may make some side effects such as dizziness, trouble sleeping, drowsiness, trouble concentrating, and/or unusual dreams less bothersome. However, these symptoms may be more severe if efavirenz is used with alcohol or mood-altering (street) drugs. You should avoid driving or operating hazardous machinery until you know how the medication affects you. 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.

Switch to professional interaction data


caffeine food

Applies to: Dvorah (acetaminophen / caffeine / dihydrocodeine)

Consumer information for this minor interaction is not currently available. Some minor drug interactions may not be clinically relevant in all patients. Minor drug interactions do not usually cause harm or require a change in therapy. However, your healthcare provider can determine if adjustments to your medications are needed.

For clinical details see professional interaction data.

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.

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.

Save Interactions List

Sign in to your account to save this drug interaction list.

Save Interactions List

Save to My Med List

Add your drug list to My Med List to view medical information in a simple, easy-to-read, personalized format. Automatically receive FDA alerts, drug interaction warnings, plus data on food, allergy & condition interactions.