Efavirenz is an antiretroviral medicine that slows the progress of human immunodeficiency virus (HIV) infection; it is not a cure. HIV destroys cells in the body, called CD4 T cells. These cells are a type of white blood cell and are important because they are involved in protecting your body from infection. If left untreated, the HIV infection weakens your immune system so that your body cannot defend itself against bacteria, viruses and other germs. Efavirenz slows down the progress of HIV infection by reducing the amount of virus in your body. It does this by stopping the virus from copying (replicating) itself.

Treating HIV infection. It must be used in combination with other medicines. If efavirenz is taken alone to treat HIV, it may stop working.

Do NOT use efavirenz if:

  • you are allergic to any ingredient in efavirenz, including if you have developed red, swollen, blistered, or peeling skin after taking any ingredient in efavirenz
  • you have moderate to severe liver problems
  • you are taking boceprevir or carbamazepine
  • you are taking another NNRTI (eg, etravirine, delavirdine, nevirapine)
  • you are taking another medicine that contains efavirenz, unless your doctor tells you otherwise

Dizziness, trouble sleeping, drowsiness, unusual dreams, and trouble concentrating may frequently occur. These side effects may begin 1-2 days after starting this medication and usually go away in 2-4 weeks. They are also reduced by taking efavirenz on an empty stomach at bedtime. Avoid alcohol and street drugs while taking efavirenz. They may worsen these side effects.

Tiredness, headache, nausea, vomiting, and diarrhea may also occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.


Some medical conditions may interact with efavirenz. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:


  • if you are pregnant, planning to become pregnant, or are breastfeeding
  • if you are able to become pregnant
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have high cholesterol, kidney problems, or a history of abnormal liver function tests or liver problems (e.g., hepatitis)
  • if you have a history of seizures, mental or mood problems (eg, depression), or suicidal thoughts or actions
  • if you drink alcohol or have a history of alcohol or other substance abuse or dependence


Some MEDICINES MAY INTERACT with efavirenz. Tell your healthcare provider if you are taking any other medicines, especially any of the following:

  • Medicines that may harm the liver (eg, acetaminophen, isoniazid, ketoconazole, certain medicines for HIV infection, methotrexate) because the risk of liver side effects may be increased. Ask your doctor if you are unsure if any of your medicines might harm the liver
  • Many prescription and nonprescription medicines (eg, used for anxiety, birth control, blood thinning, cancer, depression or other mental or mood problems, drug or other substance abuse or dependence, emergency contraception, heartburn, hepatitis C infection, high blood pressure, high cholesterol, HIV, hormone replacement, immune system suppression, infections, irregular heartbeat or other heart problems, malaria, migraine headaches, pain, seizures, sleep medicines, smoking cessation, Tourette syndrome), multivitamin products, and herbal or dietary supplements (eg, St. John’s wort) because they may interact with efavirenz. Ask your doctor or pharmacist if you are unsure if any of your medicines might interact with efavirenz.

Symptoms of overdose may include:

  • movements of your body that you cannot control
  • dizziness
  • headache
  • difficulty concentrating
  • nervousness
  • confusion
  • forgetfulness
  • difficulty falling asleep or staying asleep
  • unusual dreams
  • drowsiness
  • hallucinations (seeing things or hearing voices that do not exist)
  • abnormally happy mood
  • strange thoughts

If overdose is suspected, bring the victim to the hospital immediately.

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