Generic Name: efavirenz (ef-a-VYE-renz)
Medically reviewed by Drugs.com. Last updated on Oct 15, 2020.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Antiretroviral Agent
Pharmacologic Class: Non-Nucleoside Reverse Transcriptase Inhibitor
Uses for efavirenz
Efavirenz is used in combination with other medicines for the treatment of the infection caused by the human immunodeficiency virus (HIV). HIV is the virus that causes acquired immune deficiency syndrome (AIDS).
Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI). It works by lowering the amount of HIV in the blood.
Efavirenz will not cure or prevent HIV infection or AIDS, however, it helps keep HIV from reproducing and appears to slow down the destruction of the immune system. This may help delay the development of problems that usually result from AIDS or HIV disease. Efavirenz will not keep you from spreading HIV to other people. People who receive efavirenz may continue to have some of the problems usually related to AIDS or HIV disease.
Efavirenz is available only with your doctor's prescription.
Before using efavirenz
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For efavirenz, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to efavirenz or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of efavirenz in children younger than 3 months of age or those who weigh less than 3.5 kilograms (kg). Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of efavirenz in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart problems, which may require caution and an adjustment in the dose for patients receiving efavirenz.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking efavirenz, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using efavirenz with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- St John's Wort
Using efavirenz with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aripiprazole Lauroxil
- Arsenic Trioxide
- Doxorubicin Hydrochloride Liposome
- Ethinyl Estradiol
- Ginkgo Biloba
- Inotuzumab Ozogamicin
- Sodium Phosphate
- Sodium Phosphate, Dibasic
- Sodium Phosphate, Monobasic
Using efavirenz with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other medical problems
The presence of other medical problems may affect the use of efavirenz. Make sure you tell your doctor if you have any other medical problems, especially:
- Alcohol or drug abuse, history of or
- Depression, history of or
- Mental illness, history of—May increase the chance of having serious psychiatric side effects.
- Hepatitis B or
- Hepatitis C or
- Liver disease or
- QT prolongation (heart rhythm problem) or
- Seizures, history of—Use with caution. May make these conditions worse.
Proper use of efavirenz
Take efavirenz exactly as directed by your doctor. Do not take it more often, and do not take it for a longer time than your doctor ordered. Also, do not change the dose or stop taking efavirenz without checking first with your doctor. When your supply of efavirenz is running low, contact your doctor or pharmacist ahead of time. Do not allow yourself to run out of efavirenz.
Efavirenz comes with a patient information insert. Read and follow the instructions carefully. Ask your doctor if you have any questions.
Keep taking efavirenz for the full time of treatment, even if you begin to feel better. It is also important that you continue taking all other medicines for HIV infection your doctor has instructed you to take. Efavirenz will not work if it is taken alone. It must be taken with other HIV medicines.
Efavirenz works best when there is a constant amount in the blood. To help keep blood levels constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times during the day. For example, if you or your child are taking one dose per day, try to take it at the same time each day. If you need help planning the best times to take your medicine, check with your doctor.
Take efavirenz on an empty stomach, preferably at bedtime. Swallow efavirenz with water. Do not break, crush, or chew the tablets.
If you or your child cannot swallow capsules or tablets, you may open the capsule and pour the contents into a small amount of soft food (eg, applesauce, grape jelly, yogurt). You may also mix it with an infant formula for young children who cannot eat solid foods yet. It must be given within 30 minutes after it has been mixed. After the mixture has been given add small amount of food or formula to the empty container and gently stir to mix any capsule contents left in it. Do not eat anything else for 2 hours after taking efavirenz with food or formula.
Tell your doctor if you take rifampin (Rifadin®, Rifamate®, Rifater®) or voriconazole (Vfend®). Your dose may need to be changed.
The dose of efavirenz 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 efavirenz. 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.
- For treatment of HIV infection:
If you miss a dose of efavirenz, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using efavirenz
It is very important that your doctor check the progress of you or your child at regular visits, to make sure efavirenz is working properly. Blood tests may be needed to check for unwanted effects.
Using efavirenz 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 efavirenz and for 12 weeks after stopping it. If you think you have become pregnant while using the medicine, tell your doctor right away.
Efavirenz 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 efavirenz 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 efavirenz, 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.
Efavirenz 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 efavirenz 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 efavirenz, 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 efavirenz. 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.
Efavirenz 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.
Efavirenz 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 efavirenz before you have any medical tests. The results of some tests may be affected by efavirenz.
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.
Efavirenz side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- skin rash or itching
- Blood in the urine
- difficult or painful urination
- pain in the lower back or side
- Abdominal or stomach pain
- changes in vision
- clumsiness or unsteadiness
- convulsions (seizures)
- dark urine
- double vision
- fast or pounding heartbeat
- fever or chills
- headache (severe and throbbing)
- inappropriate behavior
- loss of appetite
- mood or mental changes (severe)
- muscle cramps or pain
- nausea or vomiting
- nerve pain
- open sores
- pain, tenderness, bluish color, or swelling of the leg or foot
- rapid weight gain
- seeing, hearing, or feeling things that are not there
- sense of constant movement of self or surroundings
- sores, ulcers, or white spots in the mouth or on the lips
- speech disorder
- swelling or tenderness in the upper abdominal or stomach area
- swelling of the hands, arms, feet, or legs
- thoughts of suicide or attempts at suicide
- tightness in the chest
- tingling, burning, numbness, or pain in the hands, arms, feet, or legs
- tingling, burning, or prickling sensations
- troubled breathing
- unusual tiredness
- weight loss
- yellow eyes or skin
Incidence not known
- Actions that are out of control
- attack, assault, or force
- continuing vomiting
- decreased awareness or responsiveness
- delusions of persecution, mistrust, suspiciousness, or combativeness
- difficult or labored breathing
- early appearance of redness or swelling of the skin
- general feeling of tiredness or weakness
- irregular heartbeat recurrent
- late appearance of rash with or without weeping blisters that become crusted, especially in sun-exposed areas of the skin, may extend to unexposed areas
- light-colored stools
- mimicry of speech or movements
- peculiar postures or movements, mannerisms, or grimacing
- severe sleepiness
- talking, feeling, and acting with excitement
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- increased sweating
- poor concentration
- trouble sleeping
Less common or rare
- Abnormally decreased sensitivity, particularly to touch
- agitation or anxiety
- change in sense of taste or smell
- dry mouth
- excessive gas
- false sense of well-being
- flaking and falling off of the skin
- general feeling of discomfort
- joint pain
- lack of feeling or emotion
- loss of hair
- loss of memory
- loss of sense of reality
- mood changes
- painful, red, hot, or irritated hair follicles
- ringing in the ears
- stomach discomfort
- unusual dreams
Incidence not known
- Difficulty having a bowel movement (stool)
- discoloration of the fingernails or toenails
- dizziness or lightheadedness
- feeling of constant movement of self or surroundings
- increased amount of fat in the upper back and neck, or around the chest and stomach area
- lose fat from the legs, arms, and face
- sensation of spinning
- swelling of the breasts or breast soreness in both females and males
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Frequently asked questions
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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
More about efavirenz
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
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- Drug Interactions
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- Drug class: NNRTIs
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