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Generic name: efavirenz [ e-FAV-ir-enz ]
Brand name: Sustiva
Dosage forms: oral capsule (200 mg; 50 mg), oral tablet (600 mg)
Drug class: NNRTIs

Medically reviewed by on Nov 13, 2023. Written by Cerner Multum.

What is efavirenz?

Efavirenz is an antiviral medicine that prevents human immunodeficiency virus (HIV) from multiplying in your body.

Efavirenz is used to treat HIV, the virus that can cause acquired immunodeficiency syndrome (AIDS). Efavirenz is for adults and children who are at least 3 months old and weigh at least 8 pounds. Efavirenz is not a cure for HIV or AIDS.

Efavirenz may also be used for purposes not listed in this medication guide.

Efavirenz side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Efavirenz may cause serious side effects. Call your doctor at once if you have:

Psychiatric symptoms or nervous system problems may happen even months or years after you have been taking efavirenz.

Efavirenz affects your immune system, which may cause certain side effects (even weeks or months after you've taken efavirenz). Tell your doctor if you have:

Common side effects of efavirenz may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


You should not use efavirenz if you also take elbasvir and grazoprevir (Zepatier) to treat hepatitis C.

Before taking this medicine

You should not use efavirenz if you are allergic to it, or if you also take elbasvir and grazoprevir (Zepatier) to treat hepatitis C.

Do not take with Atripla (combination efavirenz, emtricitabine, and tenofovir), unless your doctor tells you to.

Tell your doctor if you have ever had:

Do not use efavirenz if you are pregnant. It could harm the unborn baby or cause birth defects. Use 2 forms of birth control, including a barrier form (condom, diaphragm, cervical cap, or contraceptive sponge) to prevent pregnancy while you are using efavirenz and for at least 12 weeks after your last dose. Tell your doctor if you become pregnant during treatment.

Hormonal contraception (birth control pills, injections, implants, skin patches, and vaginal rings) may not be effective enough to prevent pregnancy while you are taking efavirenz.

HIV can be passed to your baby if the virus is not controlled during pregnancy. Your name may be listed on a registry to track any effects of antiviral medicine on the baby.

Women with HIV or AIDS should not breast-feed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

How should I take efavirenz?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Efavirenz must be given in combination with other antiviral medications and it should not be used alone. Your disease may become resistant to efavirenz if you do not take it in combination with other HIV medicines your doctor has prescribed.

Take efavirenz on an empty stomach at bedtime.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

Swallow the tablet whole and do not crush, chew, or break it.

If you cannot swallow a capsule whole, open it and sprinkle the medicine into a spoonful of applesauce, yogurt, grape jelly, or infant formula (if you are giving the medicine to a baby). Swallow the mixture right away. Do not save it for later use.

After taking efavirenz using the sprinkle method, do not eat for the next 2 hours. If you give efavirenz mixed with infant formula to a baby, do not feed more formula for at least 2 hours afterward.

Efavirenz doses are based on weight in children. Your child's dose needs may change if the child gains or loses weight.

You will need frequent medical tests.

Take efavirenz regularly to get the most benefit. Skipping doses may increase the risk of your virus becoming resistant to antiviral medicine.

Store at room temperature away from moisture and heat.

This medicine may affect a drug-screening urine test and you may have false results. Tell the laboratory staff that you use efavirenz.

Use all HIV medications as directed and read all medication guides you receive. Do not change your dose or dosing schedule without your doctor's advice. Every person with HIV should remain under the care of a doctor.

Efavirenz dosing information

Usual Adult Dose for HIV Infection:

600 mg orally once a day

-This drug should be used with a protease inhibitor and/or NRTIs.

Use: In combination with other antiretroviral agents, for the treatment of HIV-1 infection

Usual Adult Dose for Nonoccupational Exposure:

US CDC recommendations: 600 mg orally once a day
Duration of therapy: 28 days

-This drug should be used with (lamivudine or emtricitabine) plus (zidovudine or tenofovir); recommended as the preferred NNRTI-based regimen for nonoccupational postexposure prophylaxis of HIV infection.
-Prophylaxis should be started as soon as possible, within 72 hours of exposure.
-Not approved by US FDA.

Usual Adult Dose for Occupational Exposure:

US Public Health Service working group recommendations: 600 mg orally once a day
Duration of therapy: 28 days, if tolerated

-An alternative antiretroviral agent for use as HIV postexposure prophylaxis only with expert consultation
-Prophylaxis should be started as soon as possible, preferably within hours after exposure.
-The optimal duration of prophylaxis is unknown and may differ based on institution protocol.
-The most current therapeutic guidelines should be consulted for more information.
-Not approved by US FDA.

Usual Pediatric Dose for HIV Infection:

3 months or older:
3.5 to less than 5 kg: 100 mg orally once a day
5 to less than 7.5 kg: 150 mg orally once a day
7.5 to less than 15 kg: 200 mg orally once a day
15 to less than 20 kg: 250 mg orally once a day
20 to less than 25 kg: 300 mg orally once a day
25 to less than 32.5 kg: 350 mg orally once a day
32.5 to less than 40 kg: 400 mg orally once a day
40 kg or more: 600 mg orally once a day

Use: In combination with other antiretroviral agents, for the treatment of HIV-1 infection

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Get your prescriptions refilled before you run out of medicine completely.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking efavirenz?

Avoid driving or hazardous activity until you know how efavirenz will affect you. Your reactions could be impaired.

Drinking alcohol can increase certain side effects of efavirenz.

Using this medicine will not prevent your disease from spreading. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HIV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.

What other drugs will affect efavirenz?

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Efavirenz can cause a serious heart problem. Your risk may be higher if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

Other drugs may affect efavirenz, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.