Drug Interaction Report

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, sulfamethoxazole 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 sulfamethoxazole. 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.

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.

Food significantly increases the absorption of paritaprevir. You should take each dose of paritaprevir with a meal. Taking it on an empty stomach may lead to inadequate blood levels and reduced effectiveness of the medication.

Ask your doctor before using sulfamethoxazole together with ethanol (alcohol). Contact your doctor if you experience unpleasant side effects such as fast heartbeats, warmth or redness under your skin, tingly feeling, nausea, or vomiting. If you experience these side effects, you may need to avoid ethanol (alcohol) while taking sulfamethoxazole. You should check your food and medicine labels to see if these products contain ethanol (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.