Sustiva (Efavirenz) – Oral

What Is Sustiva?

Sustiva (efavirenz) is a prescription drug used to treat human immunodeficiency virus (HIV) infection. It may be used alone or with other HIV medications. It is approved for use in adults and children at least 3 months old who weigh 3.5 kilograms, about 7.7 pounds, or more.

Efavirenz belongs to a drug class called non-nucleoside reverse transcriptase inhibitor. It blocks an enzyme called reverse transcriptase. This stops the HIV-infected cells from making new viruses and reduces the viral load count.

Sustiva is available in capsule and tablet forms to be taken by mouth.

Drug Facts

Generic Name: Efavirenz

Brand Name(s): Sustiva

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Antiretroviral agent

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Efavirenz

Dosage Form(s): Tablet, capsule

What Is Sustiva Used For?

Sustiva treats HIV infection in adults and children at least 3 months old, weighing at least 3.5 kilograms (about 7.7 pounds). It is typically used in combination with other HIV medications, or antiretroviral therapy (ART).

How to Take Sustiva

Take Sustiva once daily by mouth with a full glass of water. Take it on an empty stomach. Taking this medicine with food may increase the levels of this drug in your system, which may cause more side effects. It is also best to take it at bedtime to prevent nervous system side effects like severe dizziness.

Swallow the tablets or capsule whole. Do not chew, crush, or break them.

If you cannot swallow the capsules, you can sprinkle the contents of the capsule on a small amount of soft food (yogurt, applesauce, grape jelly), as follows:

  • Add 1 to 2 teaspoons of food in a small container.
  • Hold the capsule horizontally over the meal and carefully twist it open in opposite directions, dispersing the contents.
  • If more than one capsule is needed, blend the contents of all capsules in 1 to 2 teaspoonfuls of food. Do not add any extra food.
  • Use a small spoon to gently mix the capsule's contents with the food before taking the entire mixture.

Efavirenz has a peppery flavor. You may use grape jelly to improve its taste.

If giving the medicine to an infant who cannot eat solid food, in a small bowl, mix the capsule's contents into 2 teaspoons of room-temperature liquid infant formula. Stir well, and then draw up the mixture into a 10 milliliter syringe to be given to the baby. Also:

  • Add 2 teaspoons of formula to the container to pick up any remaining Sustiva residue and feed it to the patient.
  • Give the medicine within 30 minutes of mixing.
  • For the next two hours after taking medication, do not give any more food or additional formula to your baby.


Store at room temperature (77 degrees F) in a dry place. Do not store it in your bathroom. If necessary, you may keep it between cool and mildly hot temperatures (59 and 86 degrees) for temporary periods. Keep all medications out of the reach of children and pets.

Discard all expired and unused medicines. Do not toss them down the sink or toilet. Ask your pharmacist about the best ways to dispose of your prescription. Look for drug take-back programs in your area.

How Long Does Sustiva Take to Work?

It takes three to five hours for this drug to peak in your system. Taking it with high-calorie or high-fat food increases how fast your body may absorb it.

What Are the Side Effects of Sustiva?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider or pharmacist. You may report side effects to the Food and Drug Administration (FDA) at or 800-FDA-1088.

Common Side Effects

Sustiva may or may not cause side effects. Contact your healthcare provider immediately if your side effects do not go away or become bothersome.

Some common side effects of Sustiva are:

  • Diarrhea
  • Fatigue
  • Vomiting
  • Headache
  • Nausea
  • Abnormal dreams
  • Trouble sleeping
  • Trouble focusing
  • Loss of strength and energy
  • Skin rash

Severe Side Effects

Contact your healthcare provider immediately if you experience any serious adverse effects. If you have a medical emergency or if your symptoms are life-threatening, dial 911.

Severe side effects of Sustiva include:

  • Central nervous system (CNS) symptoms, such as confusion, dizziness, hallucinations, trouble with memory, balance problems, abnormal movements, and mood or behavioral changes
  • Seizures
  • Infection
  • Changes in body fat
  • Liver problems
  • Stevens-Johnson syndrome (rare disorder of the skin or mucous membranes) or toxic epidermal necrolysis (life-threatening disorder causing blistering and peeling skin)
  • Allergic reaction

CNS effects can happen within one or two days of starting this medicine. As your body gets used to it, CNS symptoms usually go away within two to four weeks.

You may see a mild to moderate rash within two weeks of starting your treatment. It should disappear within a month if you keep using this drug. If the rash is severe, stop using it and get medical help immediately.

This is not a complete list of all the potential side effects. Speak with your healthcare provider if you have any concerns.

Long-Term Side Effects

Long-term use of efavirenz is linked to decreased cognitive function in people with HIV.

Additionally, late-onset nerve damage can occur, including losing muscle control of arms and legs and experiencing brain damage. This can happen within months or years after starting Sustiva.

All infants exposed to antiretroviral medications like Sustiva are observed for any abnormalities.

Report Side Effects

Sustiva may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Sustiva Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (capsules or tablets):
    • For treatment of HIV infection:
      • Adults—600 milligrams (mg) once a day, taken with other medicines.
      • Children 3 months of age and older (by weight)—
        • 3.5 to 5 kilograms of body weight: 100 mg once a day, taken with other medicines.
        • 5 to 7.5 kilograms of body weight: 150 mg once a day, taken with other medicines.
        • 7.5 to 15 kilograms of body weight: 200 mg once a day, taken with other medicines.
        • 15 to 20 kilograms of body weight: 250 mg once a day, taken with other medicines.
        • 20 to 25 kilograms of body weight: 300 mg once a day, taken with other medicines.
        • 25 to 32.5 kilograms of body weight: 350 mg once a day, taken with other medicines.
        • 32.5 to 40 kilograms of body weight: 400 mg once a day, taken with other medicines.
        • 40 kilograms of body weight or over: 600 mg once a day, taken with other medicines.
      • Children up to 3 months of age—Use and dose must be determined by your doctor.


Before starting Sustiva, your healthcare provider may test you for pregnancy. You should use hormonal birth control with barrier contraception (like condoms) while on Sustiva and for 12 weeks after stopping treatment.

Missed Dose

Try not to miss or skip any doses. However, if you do, take the missed dose as soon as you remember, unless it is too close to your next dose. Then, skip the missed dose and return to your regular dosing schedule. Do not take extra doses or two doses at a time. Call your healthcare provider if you are unsure what to do.

Overdose: What Happens If I Use Too Much Sustiva?

Overdose with this medication is uncommon. However, overdose symptoms of Sustiva may include seizures and uncontrolled muscle contractions.

What Happens If I Overdose on Sustiva?

If you think you or someone else may have overdosed on Sustiva, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Sustiva, call 911 immediately.


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It is very important that your doctor check the progress of you or your child at regular visits, to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. You should not become pregnant while you are taking this medicine and for 12 weeks after stopping it. If you think you have become pregnant while using the medicine, tell your doctor right away.

This medicine may decrease the effects of some birth control including pills, injections, or implants. To avoid getting pregnant, use an additional form of birth control along with your pills, injections, or implant and for 12 weeks after stopping it. Other forms of birth control include a condom, a diaphragm, contraceptive foam, or jelly.

Do not use this medicine if you or your child are also using Atripla®. Atripla® also contains efavirenz.

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem such as QT prolongation.

You might have mood or behavior changes with this medicine, such as feeling sad or hopeless, or getting upset easily. You could feel nervous or hostile, or have decreased awareness or responsiveness. Some people become violent and want to hurt themselves or others. Call your doctor right away if you or your child have any strange feelings, thoughts, or behaviors.

This medicine may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert.

Check with your doctor before taking efavirenz with alcohol or other medicines that affect the central nervous system (CNS). The use of alcohol or other medicines that affect the CNS with efavirenz may worsen the side effects of this medicine, such as dizziness, poor concentration, drowsiness, unusual dreams, and trouble with sleeping. Some examples of medicines that affect the CNS are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicines, medicine for depression, medicine for anxiety, prescription pain medicine or narcotics, medicine for attention deficit and hyperactivity disorder, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics.

Tell your doctor if you or your child get any type of skin rash, even a mild rash. Call your doctor right away if you or your child have a rash with blisters, a fever, mouth sores, red or irritated eyes, swelling of the face, muscle or joint pain, or muscle weakness.

Liver problems may occur while you are using this medicine. Check with your doctor right away if you or your child are having more than one of these symptoms: abdominal or stomach pain or tenderness, clay-colored stools, dark urine, a fever, a headache, itching, loss of appetite, nausea and vomiting, skin rash, swelling of the feet or lower legs, unusual tiredness or weakness, or yellow eyes or skin.

This medicine may increase the level of cholesterol and fats in your blood. If this condition occurs, your doctor may give you a medicine to lower the cholesterol and fats. Talk to your doctor if you have concerns.

Your immune system may get stronger when you start taking HIV medicines. Tell your doctor right away if you or your child notice any changes in your health. Sometimes the immune system will start to fight infections that were hidden in your body, such as pneumonia, herpes, or tuberculosis. Autoimmune disorders (eg, Graves' disease, polymyositis, and Guillain-Barré syndrome) may also occur.

Efavirenz may cause you to have excess body fat. Tell your doctor if you or your child notice changes in your body shape, including an increased amount of body fat in your neck or upper back, around your chest, or stomach area. You might also lose fat from your legs, arms, and face.

This medicine does not decrease the risk of transmitting the HIV infection to others through sexual contact or by contaminated blood. Make sure you understand and practice safe sex, even if your partner also has HIV. Avoid sharing needles with anyone.

Tell the doctor in charge that you or your child are taking this medicine before you have any medical tests. The results of some tests may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn't Take Sustiva?

Do not take Sustiva if you are hypersensitive to it or any part of its formulation. Hypersensitivity may include reactions like:

Do not take Sustiva if you are currently taking a drug used to treat hepatitis C called Zepatier (elbasvir and grazoprevir).

Do not take this medicine during your first trimester of pregnancy due to the possibility of neural tube defects.

What Other Medications Interact With Sustiva?

Certain medications may interact with Sustiva. This can affect how well Sustiva or the other medications work or increase the risk of side effects. Before starting treatment, tell your healthcare provider what other prescription or over-the-counter (OTC) medications, vitamins, or herbal supplements you take.

Do not take Sustiva with the following medications:

  • Verzenio (abemaciclib)
  • Tavneos (avacopan)
  • Stendra (avanafil)
  • Ayvakit (avapritinib)
  • Inlyta (axitinib)
  • Sirturo (bedaquiline)
  • Vocabria (cabotegravir)
  • Tabrecta (capmatinib)
  • Tegretol (carbamazepine)
  • Cotellic (cobimetinib)
  • Emflaza (deflazacort)
  • Doxorubicin
  • Zepatier (elbasvir and grazoprevir)
  • Braftovi (encorafenib)
  • Rozlytrek (entrectinib)
  • Inrebic (fedratinib)
  • Kerendia (finerenone)
  • Addyi (flibanserin)
  • Sporanox (itraconazole)
  • Dayvigo (lemborexant)
  • Sular (nisoldipine)
  • Lynparza (olaparib)
  • Pemazyre (pemigatinib)
  • Nuplazid (pimavanserin)
  • Noxafil (posaconazole)
  • Ranexa (ranolazine)
  • Nurtec ODT (rimegepant)
  • Retevmo (selpercatinib)
  • Koselugo (selumetinib)
  • Odomzo (sonidegib)
  • Tazverik (tazemetostat)
  • Ella (ulipristal)
  • Venclexta (venetoclax)
  • Lupkynis (voclosporin)
  • Zontivity (vorapaxar)
  • Brukinsa (zanubrutinib)

What Medications Are Similar?

Medications similar to Sustiva that may be used to treat HIV infection include:

This is a list of drugs also prescribed to treat HIV infection. It is not a list of medications recommended to take with Sustiva. Do not take these drugs together unless your healthcare provider tells you to. Talk to a healthcare provider or pharmacist if you have questions.

Frequently Asked Questions

  • What is Sustiva used to treat?

    Sustiva is used to treat HIV in adults and children 3 months and older who weigh at least 3.5 kilograms (about 7.7 pounds). It is used along with other antiretroviral medications.

  • What are some common side effects of Sustiva?

    Some common side effects include:

    • Diarrhea
    • Abnormal dreams
    • Trouble sleeping
    • Fatigue
    • Vomiting or nausea
    • Trouble focusing
    • Loss of strength and energy
    • Headache
  • What should I do if I miss a dose of Sustiva?

    Take the missed dose once you think of it unless it is too close to the next dose. Then, skip the missed dose and return to your regular schedule. Do not take extra or double your dose.

  • Can I take Sustiva with food?

    Take Sustiva on an empty stomach. Taking it with food increases how much of this drug your body may absorb, which can raise your chances of having side effects.

How Can I Stay Healthy While Taking Sustiva?

With today's treatment advances, people with HIV can live longer and healthier lives. Still, living with the condition can pose many challenges, such as adhering to a lifelong medication regimen.

Taking your prescriptions medication routinely is important for controlling your HIV, as it helps keep your viral load low. If you think you may forget to take your doses, set daily alarms as a reminder. Refill your prescription when it is due, so you do not run out of medication.

Remember, birth control pills may not work well to prevent pregnancy while taking this drug. Use other methods of contraception during this time. If you are or become pregnant while on this medicine, your healthcare provider may enroll you in an antiretroviral pregnancy registry (800-258-4263 or

Keep up with your scheduled medical appointments and talk to your healthcare team if you are experiencing any challenges with your condition. They can help you navigate life with HIV and provide information about different coping strategies.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. DailyMed. Label: Sustiva- efavirenz capsule, gelatin coated. Sustiva- efavirenz capsule, gelatin coated. Sustiva- efavirenz tablet, film coated tablet.

  2. Ma Q, Vaida F, Wong J, et al. Long-term efavirenz use is associated with worse neurocognitive functioning in HIV-infected patients. J Neurovirol. 2016;22(2):170-178. doi:10.1007/s13365-015-0382-7

  3. Cross HM, Chetty S, Asukile MT, Hussey HS, Lee Pan EB, Tucker LM. A proposed management algorithm for late-onset efavirenz neurotoxicity. S Afr Med J. 2018;108(4):271-274. doi:10.7196/SAMJ.2017.v108i4.12914

  4. Prescribers' Digital Reference. Efavirenz - drug summary.

By Queen Buyalos, PharmD
Queen Buyalos is a pharmacist and freelance medical writer. She takes pride in advocating for cancer prevention, overall health, and mental health education. Queen enjoys counseling and educating patients about drug therapy and translating complex ideas into simple language.