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Drug Interactions between Paxlovid and trimethoprim

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

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Interactions between your drugs


trimethoprim ritonavir

Applies to: trimethoprim and Paxlovid (nirmatrelvir / ritonavir)

The following interaction applies only if you are taking ritonavir products (e.G., Norvir, Kaletra) in a solution formulation:

Ritonavir-containing oral solutions are formulated with alcohol. In rare cases, trimethoprim may affect the breakdown of alcohol leading to what is termed a "disulfiram reaction." This condition produces unpleasant side effects such as flushing, throbbing in head and neck, throbbing headache, difficulty breathing, nausea, vomiting, sweating, thirst, chest pain, fast or pounding heartbeats, low blood pressure, dizziness, lightheadedness, blurred vision, and confusion. Let your doctor know if you experience any of these symptoms. More severe reactions may include heart attack, heart failure, unconsciousness, and convulsions. It is best to avoid drinking alcohol while you are being treated with trimethoprim. Check your food and medicine labels to be sure those products do not contain alcohol. 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.

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Drug and food interactions


ritonavir food

Applies to: Paxlovid (nirmatrelvir / ritonavir)

Ritonavir should be taken with food to lessen gastrointestinal side effects. It is important that you take this medication exactly as prescribed by your doctor. Do not change your treatment or stop treatment without first talking to your doctor.

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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.

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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.