9 mins read

Overview: Efavirenz is used to treat human immunodeficiency virus (HIV). It works by helping stop the spread of HIV in your body. Common side effects include trouble concentrating, unusual dreams, rash, dizziness, nausea and vomiting, headache, tiredness, and trouble sleeping. These side effects can sometimes be severe. Efavirenz interacts with many other medicines. Tell your health care providers about all medicines and supplements you take.

Uses

What is efavirenz used for?

Efavirenz is commonly used to treat human immunodeficiency virus (HIV) when combined with certain other HIV medicines.

Efavirenz may also be used for other conditions as determined by your health care provider.

How does efavirenz work (mechanism of action)?

Efavirenz works to help stop the spread of HIV in your body. A lower amount of HIV in your body helps protect and preserve the immune system.

How is efavirenz supplied (dosage forms)?

Brands and other names

  • Sustiva

Dosage forms and strengths

  • 50 mg, 100 mg, 200 mg oral capsules
  • 600 mg oral tablets

How should I store efavirenz?

Efavirenz should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of efavirenz?

The most common side effects of efavirenz are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Trouble concentrating
  • Unusual dreams
  • Rash (see below)
  • Dizziness
  • Nausea and vomiting
  • Headache
  • Tiredness
  • Trouble sleeping 

There may be other side effects of efavirenz that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of efavirenz?

While less common, the most serious side effects of efavirenz are described below, along with what to do if they happen.

Heart Rhythm Changes. Efavirenz may cause a rare, dangerous heart rhythm problem called QT prolongation and torsade de pointes. Some people have a higher risk of this, including people who are older, have other people in their family who have had these conditions, have low potassium or magnesium levels, or who take medicines that can prolong the QT interval. Tell your health care provider right away if you faint or have changes in your heart rate or rhythm, such as a fast or skipping heartbeat.

Mental Health Symptoms. Efavirenz may cause serious mental health symptoms, including depression, suicidal thoughts, or aggression. If you are about to harm yourself, call 911 or call or text 988, the Suicide & Crisis Lifeline. Tell your health care provider right away if you have any of the following symptoms, or if you have been told by others you have these symptoms.

  • Hearing, seeing, smelling, tasting, or otherwise perceiving things that others do not (hallucinations)
  • Delusional thoughts, such as false beliefs that you are being controlled
  • Disorganized thoughts, such as jumping between topics or having a hard time focusing
  • Sudden decline in self-care, such as personal hygiene or academic/work performance
  • Feeling unusually suspicious (paranoia), restless, agitated, aggressive, confused, or nervous
  • Thoughts of hurting yourself or other people
  • New or increased feelings of anxiety, depression, or other unusual changes in your mood or behavior

Central Nervous System (CNS) Effects. Efavirenz can commonly cause central nervous system (CNS) effects, and they can sometimes be severe. Symptoms usually start the first or second day of treatment and get better after a couple of weeks, but some symptoms can happen months or years after starting this medicine. Call your health care provider right away if you have the following symptoms.

  • Dizziness
  • Trouble sleeping
  • Confusion or trouble concentrating
  • Sleepiness or unusual dreams
  • Trouble with balance or coordination
  • Slowed reaction time
  • Memory problems

Rash or Skin Reactions. Efavirenz can commonly cause a rash. Children may be more likely to get a rash than adults. Sometimes efavirenz can cause a severe rash or skin reaction, such as Stevens-Johnson syndrome (SJS), that can lead to death if not treated. If you get a rash, call your health care provider right away. Get emergency help if you have any of the following symptoms of SJS.

  • Painful red or purple skin that looks burned and peels off
  • Flat red rash or blisters on your skin, mouth, nose, and genitals
  • Red, painful, watery eyes
  • Flu-like symptoms including fever, chills, and muscle aches

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking efavirenz. Keep all appointments for blood work to check the health of your liver. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Seizures. Some people who have taken efavirenz have reported having seizures. There are many different types of seizures and some of them are not easy to recognize. Stop taking efavirenz and call your health care provider if you have any of the following signs that a seizure is happening or could happen.

  • Muscle twitching, jerking, spasms, tremors, or other uncontrolled movements
  • Stiffening of your arms and legs
  • Feeling anxious, nervous, confused, or a sense of dread
  • Feeling dizzy or lightheaded
  • Falling or losing consciousness

Immune System Changes. When you start efavirenz, your immune system might get stronger and start fighting infections that have been hiding inside your body for a long time. The type of symptoms you may have will depend on the infection. Tell your health care provider right away if you notice any of the following new symptoms of infection.

  • Fever, sweats, chills, or muscle aches
  • Swollen lymph nodes
  • Vision problems
  • Confusion, problems talking, or headache
  • Skin problems, such as a painful rash or warts
  • Cough or coughing up blood
  • Weakness or coordination problems

Fat Redistribution. Some people taking efavirenz have changes in how their body stores fat. You may get more fat around the belly, breasts, or upper back (buffalo hump). You may lose fat in your arms, legs, face, or butt. Tell your health care provider right away if you have any of these symptoms.

High Cholesterol Levels. Efavirenz may increase the levels of cholesterol or triglycerides in your blood. Keep all appointments with your health care provider to check your blood work before starting and while you are taking this medicine.

Severe Allergic Reactions. Efavirenz may cause allergic reactions, which can be serious. Stop taking efavirenz and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use efavirenz?

Allergies to Ingredients. People who are allergic to any of the following should not take efavirenz.

  • Efavirenz
  • Sustiva
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific efavirenz products they stock.

Drug Interactions. Efavirenz should not be taken while you are using certain other medicines. Before taking efavirenz, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

What should I know about efavirenz before using it?

Do not take efavirenz unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share efavirenz with other people, even if they have the same condition as you. It may harm them.

Keep efavirenz out of the reach of children.

If you are prescribed efavirenz tablets, they should be swallowed whole (do not chew or crush) with some liquid. 

If you cannot swallow efavirenz capsules whole with liquid, you may be able to open the capsule and mix the contents in a small amount of soft food. Ask your pharmacist or other health care provider how to do this.

Taking this medicine at bedtime may help limit certain side effects.

It is important to keep all appointments, including for blood work. This helps your health care provider make sure it is safe for you to take this medicine.

Efavirenz can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how efavirenz affects you.

While efavirenz can help keep the HIV infection under control, it does not cure it. Efavirenz does not help protect against or prevent the spread of sexually transmitted infections (STIs), like herpes, gonorrhea, or chlamydia.

This medicine may affect the results of certain lab tests, such as a urine test for cannabis. Tell all of your health care providers that you are using this medicine before any lab work.

What should I tell my health care provider before using efavirenz?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if efavirenz is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Pregnancy. Efavirenz may cause harm to an unborn baby. Tell your health care provider right away if you are pregnant or plan to become pregnant. If you can get pregnant, you should use two effective forms of birth control while taking efavirenz and for 12 weeks after stopping it. Talk to your health care provider about which birth control options are best for you. If you become pregnant while taking efavirenz, you can register for the Antiretroviral Pregnancy Registry by calling 800-258-4263 or at www.apregistry.com. This registry collects safety information about the use of HIV medicines during pregnancy.

Breastfeeding. Efavirenz passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. There may be risks with breastfeeding while taking efavirenz and having HIV.

Interactions

Does efavirenz interact with foods or drinks?

Efavirenz should be taken on an empty stomach. Taking it with food may increase the risk of side effects.

The risk of certain side effects, such as dizziness and liver damage, may be increased if you drink alcohol while taking efavirenz. It is best to limit or avoid drinking alcohol while taking this medicine. 

Does efavirenz interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using efavirenz.

  • Bupropion (Wellbutrin SR, Wellbutrin XL, Aplenzin, and others), which is a medicine used to treat depression or to help quit smoking
  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), sirolimus (Rapamune), or tacrolimus (Prograf, Astagraf XL), which is a medicine that suppresses your immune system
  • Itraconazole (Sporanox, Tolsura), ketoconazole, posaconazole (Noxafil), or voriconazole (Vfend), which is a medicine used for fungal infections
  • Methadone, which is an opioid medicine used to treat pain or opioid use disorder
  • Rifabutin (Mycobutin), which is a medicine used to prevent Mycobacterium avium complex infection
  • Rifampin (Rifadin), which is a medicine commonly used to treat an infection called tuberculosis
  • Sertraline, which is a medicine commonly used for anxiety and depression
  • Warfarin, which is a blood thinner           
  • Any other medicine for HIV
  • A medicine for hepatitis C
  • Any medicine for seizures, such as carbamazepine, phenytoin, or phenobarbital
  • A macrolide antibiotic, such as clarithromycin or erythromycin (Ery-Tab and others), which is a medicine used for bacterial infections
  • A statin, such as atorvastatin (Lipitor and others), pravastatin (Pravachol), or simvastatin (Zocor), which is a medicine to lower cholesterol
  • A birth control pill, patch, vaginal ring, implant, injection, or intrauterine device (IUD) that contains hormones
  • A medicine for high blood pressure 

Many other medicines may alter the blood levels of efavirenz, and vice versa. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with efavirenz. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much efavirenz?

If you or someone else has used too much efavirenz, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of efavirenz?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

Missing doses of efavirenz can cause it to not work as well over time. So it is important not to miss or skip doses.