Skip to main content

Efavirenz tablets for HIV

Efavirenz slows the progress of HIV infection. It is one of a number of medicines that you will need to take regularly.

Take one dose daily, preferably at bedtime.

Efavirenz has been associated with some side-effects, most commonly a rash. Your doctor will discuss this with you before you start treatment.

Continue reading below

About efavirenz

Type of medicine

A non-nucleoside reverse transcriptase inhibitor antiretroviral medicine

Used for

Human immunodeficiency virus (HIV) infection (in adults and in children over 3 years of age)

Also called

Sustiva® (discontinued)
Combination brand: Atripla® (efavirenz with tenofovir and emtricitabine)

Available as


Efavirenz is an antiretroviral medicine. It is used for human immunodeficiency virus (HIV) infection. It slows the progress of HIV infection, but it is not a cure. HIV destroys cells in the body, called CD4 T cells. These cells are a type of white blood cell and are important because they are involved in protecting your body from infection. If left untreated, the HIV infection weakens your immune system so that your body cannot defend itself against bacteria, viruses and other germs. Efavirenz slows down the progress of HIV infection by reducing the amount of virus in your body. It does this by stopping the virus from copying (replicating) itself.

Efavirenz will be prescribed for you in a hospital clinic by a doctor who is a specialist. It belongs to a group of antiretroviral medicines known as non-nucleoside reverse transcriptase inhibitors. It is given alongside a number of other antiretroviral medicines, as part of a combination therapy. Taking three or more antiretroviral medicines at the same time is more effective than taking one alone. Taking a combination of different medicines also reduces the risk that the virus will become resistant to any individual medicine. It is vital to take them exactly as prescribed to maintain success and to help to prevent the virus from becoming resistant to the medicines. These medicines are usually taken for life.

Before taking efavirenz

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking efavirenz it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breastfeeding.

  • If you have any problems with the way your liver works, or if you have any problems with the way your kidneys work.

  • If you have a heart condition, such as an irregular heartbeat or heart failure.

  • If you have ever had any mental health problems.

  • If you have ever had a fit (seizure).

  • If you have been told you have very low levels of some salts in your blood.

  • If you have a rare inherited blood disorder called porphyria.

  • If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

Continue reading below

How to take efavirenz tablets

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about efavirenz, and it will also provide you with a full list of the side-effects which you could experience from taking it.

  • Take efavirenz exactly as your doctor tells you to. The usual dose for an adult is one 600 mg tablet daily. The dose will also be printed on the label of the pack to remind you about what the doctor said.

  • Efavirenz should be taken when your stomach is empty, which means taking it one hour before a meal, or waiting until two hours after you've eaten. This is because your body absorbs more efavirenz after a meal, which makes side-effects much more likely.

  • Try to take efavirenz at the same time of day each day, as this will help you to remember to take efavirenz regularly. Your doctor is likely to recommend you take your doses at bedtime.

  • Do not drink grapefruit juice while you are on efavirenz. This is because a chemical in grapefruit juice is thought to increase the amount of efavirenz in your bloodstream, making side-effects more likely.

  • If you forget to take a dose, do not 'double-up' on the following day to make up for the missed dose. Leave out the forgotten dose from the previous day and take the dose that is due as normal.

Getting the most from your treatment

  • Keep your regular appointments with your doctor so that your progress can be monitored. You will need to have regular blood tests.

  • It is important that you continue to take efavirenz and your other antiretroviral treatment regularly. This will help to prevent the HIV from becoming resistant to the medicines you are taking. Even if you miss only a small number of doses, the virus can become resistant to treatment.

  • If you develop an infection soon after you start the treatment, let your doctor know. As a result of taking efavirenz, your immune system may start fighting an infection which was present before you started the treatment, but which you may not have been aware of.

  • Follow carefully any advice your doctor gives to you about making lifestyle changes to reduce any risk of damage to your heart and blood vessels. These can include stopping smoking, eating healthily and taking regular exercise.

  • Although treatment with antiretroviral medicines may reduce the risk of you passing HIV to others through sexual contact, it does not stop it. It is important that you use condoms.

  • It is not uncommon for people with HIV to feel low or even depressed, especially soon after the diagnosis has been made and treatment has been started. If you have any feelings of depression, or any distressing thoughts about harming yourself then you should speak with your doctor straightaway.

  • Some people who have taken antiretroviral medicines (particularly over a long time) have developed a condition called osteonecrosis. This is a bone disease where bone tissue dies because there is a reduced blood supply to it. It leads to joint pains and stiffness, and can cause difficulties in movement. If you notice any of these symptoms, speak with your doctor.

  • If you buy any medicines, supplements or herbal remedies 'over the counter', check with a pharmacist that they are suitable to take with efavirenz and your other medicines. This is because some medicines interfere with antiretrovirals and can stop them from working properly. In particular, do not take St John's wort.

  • Some people taking antiretroviral medicines develop changes to the way body fat is distributed in the body. This can result in changes to body image. Your doctor will discuss the possibility of this with you.

  • If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

  • Treatment for HIV is usually lifelong. Continue to take efavirenz regularly, even if you feel well. This is to keep your immune system healthy.

Continue reading below

Can efavirenz cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with efavirenz. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common efavirenz side-effects

What can I do if I experience this?

Itchy rash (usually within the first week or so)

If this is severe, such as if blisters develop or if you also have a high temperature (fever), let your doctor know about it straightaway


Drink plenty of water to replace lost fluids

Feeling sick (nausea) or being sick (vomiting), tummy (abdominal) pain

Stick to simple meals - avoid fatty or spicy food. If it continues, speak with your doctor


Drink plenty of water and ask a pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know

Feeling dizzy or tired

Do not drive and do not use tools or machines while affected

Feeling anxious or depressed

Let your doctor know about this

Problems sleeping, lack of concentration or coordination

These usually improve after a few weeks

Changes to some blood tests (such as raised cholesterol levels)

Your doctor will check for this

If you experience any other symptoms which you think may be due to efavirenz, speak with your doctor or pharmacist for further advice.

How to store efavirenz

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article History

The information on this page is written and peer reviewed by qualified clinicians.

symptom checker

Feeling unwell?

Assess your symptoms online for free