What is Evotaz?

Evotaz is a medication used to treat HIV. It is a combination of an antiretroviral drug called atazanavir and a booster drug called cobicistat in one pill. The usual adult dose is one pill taken once a day along with other antiretroviral drugs.

Evotaz combines 300mg atazanavir and 150mg cobicistat in a pink, oval, film-coated tablet. The tablet has ‘3641’ on one side.

How does Evotaz work?

Evotaz combines two drugs in one pill. The drug atazanavir is from a class of drugs known as protease inhibitors. The drug cobicistat increases or ‘boosts’ the level of atazanavir. Your doctor will prescribe Evotaz as part of your HIV treatment, along with antiretrovirals from another class of drugs. It is important to take all the drugs as prescribed, every day. Each drug class works against HIV in a different way.

The aim of HIV treatment is to reduce the level of HIV in your body (viral load). Ideally, your viral load should become so low that it is undetectable – usually less than 50 copies of virus per ml of blood. Taking HIV treatment and having an undetectable viral load protects your immune system and stops HIV being passed on to someone else during sex.

How do I take Evotaz?

You should take Evotaz once a day with food.

HIV treatment works best if you take it every day. When would be a good time for you to plan to take your treatment? Think about your daily routine and when you will find it easiest to have a regular meal or snack and take your treatment.

If you forget to take a dose of Evotaz, take it as soon as you remember. If it has been more than 12 hours since your dose was due, then don’t take a double dose, just skip the dose you’ve forgotten and carry on.

If you regularly forget to take your treatment, or you aren’t taking it for another reason, it’s important to talk to your doctor about this.

What are the possible side effects of Evotaz?

All drugs have possible side effects. It’s a good idea to talk to your doctor about possible side effects before you start taking a drug. If you experience something that might be a side effect, talk to your doctor about what can be done. A full list of side effects, including less common side effects, should be included in the leaflet that comes in the packaging with Evotaz.

We generally divide side effects into two types:

Common – a side effect that occurs in at least one in a hundred people (more than 1%) who take this drug.

Rare – a side effect that occurs in fewer than one in a hundred people (less than 1%) who take this drug.

Common side effects of Evotaz include (most common in bold):

Yellowing of the skin or eyes (jaundice), nausea, increased appetite, sense of taste affected, dry mouth, headache, dizziness, insomnia (difficulty sleeping), abnormal dreams, somnolence (sleepiness), vomiting, diarrhoea, abdominal pain, indigestion, bloating, flatulence, increased levels of bilirubin in the blood, rash, fatigue.

A common side effect of Evotaz is the development of a rash. This is usually mild, but in rare cases it can be the sign of a more severe reaction. It is important to tell your doctor if you develop a rash when you start Evotaz.

Does Evotaz interact with other drugs?

It’s important that your doctor and pharmacist know about any other drugs you are taking. That includes medicine prescribed by another doctor, drugs you have bought from a high-street chemist, herbal and alternative treatments, and recreational drugs.


antiretroviral (ARV)

A substance that acts against retroviruses such as HIV. There are several classes of antiretrovirals, which are defined by what step of viral replication they target: nucleoside reverse transcriptase inhibitors; non-nucleoside reverse transcriptase inhibitors; protease inhibitors; entry inhibitors; integrase (strand transfer) inhibitors.


A rash is an area of irritated or swollen skin, affecting its colour, appearance, or texture. It may be localised in one part of the body or affect all the skin. Rashes are usually caused by inflammation of the skin, which can have many causes, including an allergic reaction to a medicine.


Pain or discomfort in the chest or stomach caused by eating or drinking.

viral load

Measurement of the amount of virus in a blood sample, reported as number of HIV RNA copies per milliliter of blood plasma. Viral load is an important indicator of HIV progression and of how well treatment is working. 


undetectable viral load

A level of viral load that is too low to be picked up by the particular viral load test being used or below an agreed threshold (such as 50 copies/ml or 200 copies/ml). An undetectable viral load is the first goal of antiretroviral therapy.

Some medicines should not be taken together because if they are this can cause serious side effects, or it can stop one or both of the drugs from working. Other drug interactions are less dangerous but still need to be taken seriously. If levels of one drug are affected, you may need to change the dose you take.

A list of drugs known to have interactions with Evotaz should be included in the leaflet that comes in the packaging with Evotaz. Tell your doctor if you are taking any of these drugs, and other drugs that are not on the list.

Drugs that affect the acidity of your stomach and gastrointestinal tract can stop atazanavir being absorbed, meaning it may not be effective at suppressing HIV:

  • Proton pump inhibitors (indigestion remedies that reduce gastric acid, such as lansoprazole or omeprazole) should not be taken with atazanavir, unless they have been prescribed by your HIV doctor and the dose of atazanavir is increased.
  • Evotaz should be taken with food at the same time as, or 10 hours after, anH2-receptor antagonist. If atazanavir is taken with tenofovir, you should never take H2-receptor antagonists without speaking to your doctor or pharmacist first.
  • Indigestion remedies or calcium supplements should be taken at least two hours before or one hour after atazanavir.
  • ‘Buffered’ medicines (drugs that have been prepared so they are released slowly into the body) should be taken at least two hours before or one hour after atazanavir.

You should not take Evotaz with any of the following drugs:

  • alfuzosin
  • amiodarone
  • astemizole
  • avanafil
  • bepridil
  • carbamazepine
  • cisapride
  • colchicine
  • dihydroergotamine
  • dronedarone
  • ergometrine
  • ergonovine
  • ergotamine
  • lidocaine (injectable)
  • lovastatin
  • methylergonovine
  • midazolam (oral)
  • phenobarbital
  • phenytoin
  • pimozide
  • quetiapine
  • quinidine
  • rifampicin
  • simvastatin
  • St John’s wort
  • terfenadine
  • ticagrelor
  • triazolam

Sildenafil is a drug used to treat pulmonary arterial hypertension (high blood pressure in the lungs). You should not take sildenafil with Evotaz if sildenafil was prescribed for this reason. Sildenafil is also used to treat erectile dysfunction (impotence). If you are using sildenafil for erectile dysfunction, tell your doctor before you start treatment with Evotaz.

Can I take Evotaz in pregnancy?

If you are considering having a baby, or think you might be pregnant, talk to your doctor as soon as possible about which combination of anti-HIV medications would be right for you. It is important to take antiretroviral treatment during pregnancy to prevent passing HIV from mother to baby.

Evotaz contains two drugs: atazanavir and cobicistat. During pregnancy, the British HIV Association recommends using atazanavir and ritonavir, in place of atazanavir and cobicistat.

Women living with HIV are advised not to breastfeed, as HIV can be passed on in breast milk. However, some women do choose to breastfeed. Evotaz should not be used during breastfeeding as at least one of the drugs it contains passes into breast milk.

Can children take Evotaz?

Evotaz is not licensed for use in children.

Talking to your doctor

If you have any concerns about your treatment or other aspects of your health, it’s important to talk to your doctor about them.

For example, if you have a symptom or side effect or if you are having problems taking your treatment every day, it’s important that your doctor knows about this. If you are taking any other medication or recreational drugs, or if you have another medical condition, this is also important for your doctor to know about.

There are other things which are important to your health and HIV care, and which you and your doctor may take into account when making decisions about your treatment. For example, if you are considering having a baby, or want to start taking contraception.

Building a relationship with a doctor may take time. You may feel very comfortable talking to your doctor, but some people find it more difficult, particularly when talking about sex, mental health, or symptoms they find embarrassing. It’s also easy to forget things you wanted to talk about.

Preparing for an appointment can be very helpful. Take some time to think about what you are going to say. You might find it helpful to talk to someone else first, or to make some notes and bring them to your appointment. 

For detailed information on this drug, visit the Evotaz page in the A-Z of antiretroviral medications.

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