DRUG INTERACTIONS: The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Your doctor or pharmacist can often prevent or manage interactions by changing how you use your medications or by close monitoring.

To help your doctor and pharmacist give you the best care, be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products) before starting treatment with this product. While using this product, do not start, stop, or change the dosage of any other medicines you are using without your doctor's approval.

Do not take this medication with other products that contain efavirenz.

Other medications can affect the removal of efavirenz from your body, which may affect how efavirenz works. Examples include some drugs used to treat seizures (such as carbamazepine, phenobarbital, phenytoin), rifamycins (such as rifampin), St. John's wort, among others.

Efavirenz can speed up or slow down the removal of many other medications from your body, which may affect how they work. Examples of affected drugs include some drugs for anxiety/sleep (such as alprazolam, midazolam, triazolam), azole antifungals (such as itraconazole, ketoconazole, voriconazole), bupropion, calcium channel blockers (such as diltiazem, verapamil), cisapride, ergot drugs (such as ergotamine), macrolide antibiotics (such as clarithromycin), methadone, pimozide, rifabutin, sertraline, some cholesterol-lowering statins (such as atorvastatin, pravastatin, simvastatin), warfarin, among others.

Some other drugs to treat HIV infection (such as other NNRTIs including etravirine/nevirapine/rilpivirine) may also interact with efavirenz. If you are taking atazanavir with this medication, you may need to also take another medication (ritonavir). Consult your doctor or pharmacist for more details.

This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. However, to reduce the risk of spreading HIV to others, always use barrier protections during all sexual activity. (See also Precautions section.)

Tell your doctor or pharmacist if you are taking other products that cause drowsiness including alcohol, antihistamines (such as cetirizine, diphenhydramine), drugs for sleep or anxiety (such as diazepam, zolpidem), muscle relaxants, and narcotic pain relievers (such as codeine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

This medication may interfere with certain laboratory tests (including urine cannabinoid tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

This document does not contain all possible drug interactions. Keep a list of all the products you use. Share this list with your doctor and pharmacist to lessen your risk for serious medication problems.

OVERDOSE: If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 1-800-222-1222. Canada residents can call a provincial poison control center.

NOTES: Do not share this medication with others.

Laboratory and/or medical tests (such as liver tests, viral load, T-cell counts, cholesterol and triglyceride levels) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

Keep all medical and laboratory appointments.

MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE: Store at room temperature at 77 degrees F (25 degrees C) away from light and moisture. Brief storage between 59-86 degrees F (15-30 degrees C) is permitted. Do not store in the bathroom. Keep all medicines away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

MEDICAL ALERT: Your condition can cause complications in a medical emergency. For enrollment information call MedicAlert at 1-800-854-1166 (US) or 1-800-668-1507 (Canada).

Information last revised April 2012. Copyright(c) 2012 First Databank, Inc.