Efavirenz (Oral)

Efavirenz is a non-nucleoside reverse transcriptase inhibitor which is commonly prescribed to children and adults with HIV.


Efavirenz is usually used in combination with medicines and treatments others to treat HIV. It works to reduce the amount of human immunodeficiency virus (HIV) in the blood. HIV slowly destroys the immune system and leads to AIDS (acquired immune deficiency syndrome), and by reducing HIV levels it is possible to slow the progression of the disease.

This medicine is not a cure for HIV or AIDS. It appears to slow the destruction of the immune system, but it doesn't prevent AIDS from occurring. Furthermore, patients may still experience some of the symptoms or problems associated with HIV or AIDS. Efavirenz does not prevent HIV or AIDS either, nor does it stop the infection from being passed to other people.

Patients who take efavirenz can expect to be prescribed other additional medicines or treatments for HIV or AIDS. They should also continue to take suitable precautions to avoid spreading HIV to others.

In the US, the oral route of efavirenz is available under the brand name Sustiva and is administered in capsule or tablet dosage forms. It is only available with a doctor's prescription.

Conditions Treated?


Type Of Medicine?

  • Non-nucleoside reverse transcriptase inhibitor (NNRTI)

Side Effects

Efavirenz can cause a variety of unwanted side effects alongside its needed effects. Some side effects are serious and require urgent medical attention. Familiarize yourself with all side effects so that you can seek immediate medical care where appropriate.

The following side effects can be extremely dangerous and should be reported to a doctor immediately:

  • More common:
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  • Less common:
    • Pain in the lower back or side
    • Difficult or painful urination
    • Blood in urine
  • Rare
    • Pain in abdomen or stomach
    • Swelling or tenderness in abdomen or stomach
    • Nausea or vomiting
    • Dark urine
    • Blistering skin
    • Hives
    • Open sores
    • Ulcers, white spots or sores in mouth or on lips
    • Yellow skin or eyes
    • Pain, tenderness, swelling or bluish color of legs or feet
    • Swelling of hands, arms, feet or legs
    • Tingling, burning or numbness in hands, arms, feet or legs
    • Tinging, burning or prickling sensations
    • Vision changes
    • Double vision
    • Sense of self or surroundings moving
    • Clumsiness or unsteadiness
    • Convulsions or seizures
    • Muscle cramps or pain
    • Tremor
    • Speech disorder
    • Nerve pain
    • Fainting
    • Chills or fever
    • Confusion
    • Delusions
    • Thoughts of or attempts at suicide
    • Hallucinations (seeing, hearing or feeling things that aren't there)
    • Inappropriate behavior
    • Severe mental or mood changes
    • Abnormal tiredness
    • Loss of appetite
    • Sudden rapid weight gain
    • Unusual weight loss
    • Cough
    • Severe, throbbing headache
    • Pounding or fast heartbeat
    • Tightness in chest
    • Troubled breathing
  • Incidence unknown
    • Continuous vomiting
    • Delusional beliefs of persecution, mistrust, combativeness or suspiciousness
    • Out of control actions
    • Irritability
    • Nervousness
    • Excitability
    • Attack, assault or force
    • Labored breathing
    • Early onset or red or swollen skin
    • Late onset of rash, either with or without weeping blisters, which may become crusted
    • General weakness or tiredness
    • Irregular heartbeat
    • Light colored stools

The following side effects are minor and don't usually require medical attention unless they become very severe or prolonged. If you're concerned about them, you should talk to your doctor about them. They may dissipate once your body adjusts to the medicine, or there may be lifestyle factors you could adjust to prevent them or reduce their severity.

  • More common
    • Diarrhea
    • Headache
    • Dizziness
    • Drowsiness
    • Poor concentration
    • Difficulty sleeping
    • Reduced concentration
  • Less common or rare
    • Reduced sensitivity to touch
    • Changed sense or taste or smell
    • Dry mouth
    • Ringing in ears
    • Weakness
    • False sense of well-being
    • General sense or discomfort
    • Agitation
    • Anxiety
    • Lack of emotion or feeling
    • Loss of sense of reality
    • Mood changes
    • Memory problems
    • Unusual dreams
    • Belching
    • Excessive gas
    • Heartburn
    • Indigestion
    • Stomach discomfort
    • Flaking or peeling skin
    • Flushing
    • Joint pain
    • Hair loss
    • Painful, hot, red or otherwise irritated hair follicles
  • Incidence unknown
    • Difficulty passing stools
    • Discolored finger or toenails
    • Dizziness
    • Lightheadedness
    • Sensation of spinning
    • Increased amount of fat around chest, stomach, upper back or neck
    • Loss of fat from legs, arms and face
    • Swelling of breasts or breast soreness (possible in both men and women)

If you notice any other side effects not listed here, contact your doctor as soon as possible. You could also report new side effects to the FDA, or your doctor could do this on your behalf.


Recommended dosages

For treatment of HIV infection, adults usually taken 600 mg of efavirenz once each day at the same time as other medicines. For children aged 3 months and older doses are also given once each day at the same time as other medicines, but the dose is determined by their body weight as follows:

  • 3.5 to 5 kg' 100 mg
  • 5 to 7.5 mg' 150 mg
  • 7.5 to 15 kg' 200 mg
  • 15 to 20 kg '250 mg
  • 20 to 25 kg' 300 mg
  • 25 to 32.5 kg' 350 mg
  • 32.5 to 40 kg' 400 mg
  • 40 kg or over' 600 mg

For children under the age of 3 months or weighing less than 3.5 kg, the use of efavirenz must be determined by a doctor. There is little evidence on the safety and efficacy of efavirenz on this population.

Your dose of efavirenz may differ from that listed here depending on your medical history. Always follow your doctor's instructions and never take more efavirenz than is prescribed to you.

How to take efavirenz

Efavirenz should be taken on an empty stomach, preferably at bedtime since it can induce drowsiness. You should swallow the tablets or capsules whole without chewing, crushing or breaking them.

If you have trouble swallowing capsules, you could mix the contents of the capsule with one or two teaspoons of soft food, such as jelly, yogurt or applesauce. Be careful to avoid spilling the contents of the capsule during preparation. Eat the mixture within 30 minutes of preparing it, then add a teaspoon more of the soft food to the container, mix again and eat to ensure all traces of the medicine have been consumed. Avoid eating within the following two hours.

For infants who are too young to swallow tablets or capsules or eat solid food, you can mix efavirenz with two teaspoons of their room-temperature formula in a container. The formula should be consumed within 30 minutes of the medicine being mixed into it. Feed the mixture to the infant with a syringe. Add two more teaspoons of formula to the empty container, then stir and feed to the baby to ensure all traces of the medicine have been consumed. Do not give efavirenz to the baby in a bottle, and avoid feeding the baby again within two hours.

Missed doses

If you forget to take a dose of efavirenz, take it as soon as you remember. However, if it is almost time for your next dose of efavirenz when you remember, simply skip the missed dose and return to your normal dosing schedule. Avoid taking multiple doses of efavirenz together to make up for missed doses, as doing so could increase the risk of harmful side effects.


There are many medicines which interact with efavirenz and it is very important that your doctor knows about all the drugs you currently take, including those prescribed and those purchased over the counter. Some herbal medicines, supplements or multivitamins may also interact with efavirenz, so tell your doctor about these, too. It may be helpful to keep a list of your medications to present to all doctors, nurses and pharmacists you see to ensure harmful interactions do not occur.

It is particularly important that your doctor knows you are taking the following types of medicines:

  • Antidepressants
  • Anxiety medicines
  • Medicines for other mental health conditions
  • Seizure medicines
  • Sedatives
  • Sleeping pills
  • Tranquilizers
  • Warfarin
  • Hormonal contraceptives

Efavirenz should never be taken at the same time as the following medicines. If you take any of these medicines, your doctor will either choose not to prescribe efavirenz or they may change some of the medicines you currently take.

  • Amifampridine (Firdapse)
  • Amisulpride
  • Bepridil (Vascor)
  • Carbamazepine (Carbatrol, Epitol, Equetro, TEGretol, TEGretol XR)
  • Cisapride (Propulsid)
  • Dasabuvir (found in Viekira Pak, Viekira XR)
  • Dronedarone (Multaq)
  • Elbasvir (Zepatier)
  • Grazoprevir (Zapatier)
  • Mesoridazine (Serentil)
  • Paritaprevir (found in Viekira Pak, Viekira XR)
  • Pimozide (Orap)
  • Piperaquine
  • Ritonavir (found in Viekira Pak, Viekira XR)
  • Saquinavir (Invirase, Fortovase)
  • Sparfloxacin (Zagam)
  • St John's Wort
  • Terfenadine (Seldane)
  • Thioridazine (Mellaril, Mellaril-S)
  • Voriconazole (VFEND)
  • Ziprasidone (Geodon)

There are also many other medicines which interact with efavirenz, but in instances where both medicines are vital, they may still be prescribed together. Your doctor may adjust the dosages of the medicines to minimize harmful interactions, or they may give you new instructions as to the times of day at which to take your medicines. Always follow your doctor's instructions closely.

Medical interactions

In people with the following medical problems, or a history of them, efavirenz could increase the risk of serious psychiatric side effects:

  • Alcohol abuse
  • Drug abuse
  • Depression
  • Other mental illness

The following medical conditions may be worsened by efavirenz:


Risk of mental health problems

Sometimes efavirenz can cause serious mental health conditions which may lead patients to suicidal thoughts or actions. If you have a history of depression, anxiety, suicidal ideation, self-harm or delusions, make sure your doctor knows as you could be at a higher risk of mental health problems when taking efavirenz.

If you notice any signs of diminishing mental health while taking efavirenz, tell your doctor as soon as possible. Signs include:

  • Sadness
  • Hopelessness
  • Anxiety
  • Restlessness
  • Thoughts or suicide or self-harm
  • Seeing, hearing or feelings things that aren't real (hallucinations)
  • Delusions (being unable to tell what is real and what is not)
  • Having trouble trusting others
  • Speaking or moving abnormally

Risk of liver problems

Efavirenz can cause serious liver problems, particularly in those who already have hepatitis B virus infection (HBV) or hepatitis C virus infection (HCV). You can expect your doctor to requests tests to assess your liver function both before you begin efavirenz treatment and on a regular basis for as long as you take the medicine. If tests demonstrate signs of decreased liver function, you may not be able to take this medicine.

While taking efavirenz, look out for signs of liver problems and report them to your doctor straight away. Signs include:

  • Jaundice (yellowed skin or eyes)
  • Dark-colored urine
  • Light, clay-colored stools
  • Loss of appetite which lasts for several days or more
  • Nausea
  • Pain in abdomen or lower stomach area

Risk of rash

One of the more common side effects associated with efavirenz is skin rash and itching, and in many instances, it is relatively minor and goes away within four weeks of starting the medicine. However, in some instances rashes can become severe and can lead to serious complications. It is safest to report any rash to your doctor, but it's particularly important to seek medical attention if you notice any of the following severe symptoms along with the rash:

  • Swelling of face, eyes, lips or tongue
  • Peeling skin
  • Blisters or lesions
  • Sores in mouth
  • Red or inflamed eyes like conjunctivitis (often called pink eye)
  • Fever

Pregnancy and breastfeeding

Efavirenz is an FDA pregnancy category D drug, which means that it should not be taken during pregnancy. Both animal and human studies have demonstrated that the drug could cause serious birth defects. You should avoid becoming pregnant while taking this medicine and for up to 12 weeks after you stop taking it. If you become pregnant while taking efavirenz, contact your doctor immediately.

It is believed that efavirenz is excreted in human breast milk, but it is not known what effect it may have on nursing infants. However, breastfeeding is generally not recommended for women with HIV infection, as they risk transmitting the infection to the nursing child. Use an alternative feeding method where possible or consult your doctor if breastfeeding is absolutely necessary.

Hormonal contraceptives

Efavirenz can decrease the effectiveness of hormonal contraceptives. Tell your doctor if you are taking birth control pills, patches, implants, injections or rings. You will need to use barrier birth control methods (such as condoms or a diaphragm) in addition to your usual birth control for as long as you are taking efavirenz. Consult your doctor to find a suitable birth control method.

Elderly patients

Efavirenz appears to be just as useful to geriatric patients as it is to younger adults. However, since elderly patients are more likely to have liver problems, it is often used with greater caution in this population. Lower doses may be administered initially to minimize the risk of severe liver problems occurring.

Allergic reaction

You should tell your doctor about all allergies you suffer from (including drug, chemical, preservative, animal, food and pollen allergies) to avoid you have a serious reaction to any of the ingredients in efavirenz. If you have had an allergic reaction to efavirenz in the past or to other NNRTIs or drugs like it, you may not be able to take efavirenz.

Seek immediate medical care if you notice any of the following signs of allergic reaction:

  • Rash, hives or itching
  • Shortness of breath
  • Wheezing
  • Swelling of face, lips, tongue or throat
  • Cough

Reducing the risk of HIV transmission

Efavirenz does not stop the transmission of HIV. You should, therefore, take precautions to avoid passing the infection to other people, such as:

  • Using latex or polyurethane condoms during sex
  • Avoiding shared needles
  • Avoiding shared razors
  • Avoiding shared toothbrushes


Efavirenz can cause drowsiness or dizziness. Avoid driving or operating machinery when you first begin taking the medicine until you know how it affects you. Alcohol may heighten drowsiness or dizziness so avoid it while taking efavirenz.

Avoid grapefruit

Grapefruit and grapefruit juice may affect the way efavirenz is processed by the body. Ask your doctor whether it is safe to consume grapefruit or grapefruit juice when you are prescribed this medicine.


Store efavirenz in the container it is provided in at room temperature and away from heat, direct light or moisture. Keep it up and away from the ground so that it is not within easy reach of children. If you have expired or unused medicine, ask your healthcare provider how to dispose of it correctly.


Efavirenz is a HIV treatment commonly used in combination with other medicines to slow the progression of HIV and AIDS. It is not a cure for HIV, nor does to prevent it, but it works to reduce the amount of HIV in the blood in order to slow the progression of immune system destruction.

Efavirenz can cause serious skin rash, serious liver problems and serious mental health problems. It should be used with caution in patients with a history of liver disease, hepatitis B, hepatitis C, depression, suicidal ideation and other mental illnesses.

The oral route of efavirenz is administered in tablet and capsule dosage forms. Usually, the tablets or capsules are swallowed whole with a little water and on an empty stomach at the same time as other medicines. However, infants who are too young to swallow tablets may be prescribed capsules, the contents of which can be mixed with a small amount of formula. For children and adults who have trouble swallowing, the capsule contents may be mixed with a little soft food.