Efavirenz (By mouth)


Efavirenz (ef-a-VYE-renz)

Used with other medicines to treat human immunodeficiency virus (HIV) infection. HIV causes acquired immune deficiency syndrome (AIDS). Efavirenz does not cure HIV or AIDS, but it may slow the worsening of the disease.

Brand Name(s)


There may be other brand names for this medicine.

When This Medicine Should Not Be Used

Do not use this medicine if you have had an allergic reaction to efavirenz, or if you are pregnant. Do not use this medicine if you also use St John's wort, bepridil (Vascor®), cisapride (Propulsid®), midazolam (Versed®), pimozide (Orap®), triazolam (Halcion®), or ergot medicines (such as dihydroergotamine, ergonovine, ergotamine, methylergonovine, Cafergot®, Ergomar®, Wigraine®).

How to Use This Medicine

Capsule, Tablet

  • Your doctor will tell you how much of this medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.Efavirenz is used with other medicines to treat HIV infection. Make sure you take all of your medicines as your doctor has prescribed.
  • Do not change or stop using this medicine without checking with your doctor first. When your supply of this medicine is running low, contact your doctor or pharmacist ahead of time. Do not allow yourself to run out of this medicine.
  • Take this medicine on an empty stomach, preferably at bedtime. Swallow this medicine with water. Do not break, crush, or chew the tablets.
  • This medicine comes with patient instructions. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions.

If a dose is missed:

  • If you miss a dose or forget to use your medicine, use it as soon as you can. If it is almost time for your next dose, wait until then to use the medicine and skip the missed dose. Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • There are many other drugs that may interact with efavirenz. These drugs can cause problems that are serious, even life-threatening. Make sure your doctor knows about all other medicines you are using. Tell your doctor if you change a dose of another medicine or stop taking another medicine. Your dose of efavirenz may need to be changed also.
  • Tell your doctor if you take rifampin (Rifadin®, Rifamate®, Rifater®) or voriconazole (Vfend®). Your dose may need to be changed.
  • Do not take Atripla® while you are being treated with this medicine. Atripla® also has efavirenz in it.
  • Make sure your doctor knows if you are using medicines to treat an infection (such as clarithromycin, rifabutin, Biaxin®, Mycobutin®), an estrogen hormone replacement or birth control pill (such as ethinyl estradiol, norgestimate, Estinyl®, Ortho-Cyclen®, Ortho Tri-Cyclen®), birth control implant (such as etonogestrel, Implanon®), or a blood thinner (such as warfarin, Coumadin®, Jantoven®). Tell your doctor if you are also using other medicines to treat HIV/AIDS (such as amprenavir, atazanavir, fosamprenavir, indinavir, lopinavir, maraviroc, raltegravir, ritonavir, saquinavir, Agenerase®, Crixivan®, Isentress®, Kaletra®, Lexiva®, Norvir®, Reyataz®, Selzentry®), or medicine to treat hepatitis C (such as boceprevir, telaprevir, Incivek®, Victrelis®).
  • Make sure your doctor knows if you also use medicine to treat seizures (such as carbamazepine, phenobarbital, phenytoin, Carbatrol®, Dilantin®, Tegretol®), medicine to treat fungus infections (such as itraconazole, ketoconazole, posaconazole, Nizoral®, Noxafil®, Sporanox®), or medicine to treat depression (such as bupropion, sertraline, Wellbutrin®, Zoloft®, Zyban®). Tell your doctor if you also use certain blood pressure medicines (such as diltiazem, felodipine, nicardipine, nifedipine, verapamil, Cardene®, Cardizem®), medicine to lower cholesterol (such as atorvastatin, pravastatin, simvastatin, Lipitor®), medicine that weakens the immune system (such as cyclosporine, sirolimus, tacrolimus, Gengraf®, Neoral®, Protopic®, Rapamune®, Sandimmune®), or pain medicine (such as methadone, Dolophine®).
  • Tell your doctor if you are using any medicines that make you sleepy. These include sleeping pills, cold and allergy medicine, narcotic pain relievers, and sedatives.
  • Do not drink alcohol while you are using this medicine.Alcohol may cause you to feel more lightheaded, dizzy, or drowsy when used with this medicine.

Warnings While Using This Medicine

  • You can harm your unborn baby if you use this medicine while you are pregnant. Use an effective form of birth control to prevent pregnancy. You should not become pregnant while you take this medicine and for 12 weeks after you stop taking it. If you think you have become pregnant, tell your doctor right away.
  • Birth control pills, implants, and other forms of hormonal birth control may not work as well while you are using efavirenz. Use an additional form of birth control while you take this medicine and for 12 weeks after you stop taking it.
  • You should not breastfeed if you have HIV or AIDS, because you might give the infection to your baby through your breast milk.
  • Tell your doctor if you have a history of liver disease or hepatitis B or C. Make sure your doctor knows if you have a history of seizures, mental illness, emotional problems, or drug abuse. Tell your doctor if you currently use alcohol. Make sure your doctor knows about any other medical problems you currently have or have had in the past.
  • This medicine may increase your risk of serious mental or behavioral problems. Tell your doctor if you develop any mood changes, strange thoughts, or unusual behavior.
  • Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.
  • This medicine may increase the level of cholesterol and fats in your blood. Talk to your doctor if you have concerns.
  • Your immune system may get stronger when you start taking HIV medicines. If you have infections that are hidden in your body, such as pneumonia or tuberculosis, you may notice new symptoms when your body tries to fight them. Be sure to tell your doctor if this occurs.
  • This medicine will not keep you from giving HIV to your partner during sex. Make sure you understand and practice safe sex, even if your partner also has HIV. Do not share needles with anyone.
  • This medicine may cause changes in your body fat. Tell your doctor if you notice more fat in your upper back and neck or around the chest and stomach area. You may also lose fat from your legs, arms, and face.
  • This medicine may make you dizzy or drowsy. Do not drive, use machines, or do anything else that could be dangerous until you know how this medicine affects you.
  • Check with your doctor right away if you develop a skin rash, blistering, peeling, or loose skin, sores, ulcers, or red lesions on the skin, or fever or chills. These could be symptoms of a serious skin reaction.
  • Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.
  • Your doctor will need to check your blood at regular visits while you are using this medicine. Be sure to keep all appointments.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, red skin rash
  • Dark urine or pale stools, loss of appetite, yellow skin or eyes
  • Fast or pounding heartbeat
  • Lightheadedness or fainting
  • Seizures
  • Severe depression, anxiety, mood changes, hallucinations, problems dealing with anger, thoughts of hurting yourself or others
  • Sudden and severe stomach pain, nausea, vomiting

If you notice these less serious side effects, talk with your doctor:

  • Diarrhea, stomach pain, upset stomach
  • Dizziness or headache
  • Fever or cough (in children)
  • Mild skin rash or itching
  • Tiredness
  • Trouble sleeping or concentrating, strange dreams
  • Weight gain around your neck, upper back, breast, face, or waist

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last Reviewed on 06/12/2013

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch)

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

This page was last updated: September 18, 2013

Average rating (0)