What is Rezolsta?

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

Rezolsta combines 800mg darunavir and 150mg cobicistat in a pink, oval, film-coated tablet. The tablet has ‘800’ on one side and ‘TG’ on the other side.

How does Rezolsta work?

Rezolsta combines two drugs in one pill. The drug darunavir is from a class of drugs known as protease inhibitors. The drug cobicistat increases or ‘boosts’ the level of darunavir. Your doctor will prescribe Rezolsta 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 Rezolsta?

You should take Rezolsta once a day with some liquid, such as water or milk.

You should always take Rezolsta with food so that it can work properly. It is recommended that you have a meal or a snack and then take your dose of Rezolsta within 30 minutes.

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 Rezolsta, 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 Rezolsta?

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 Rezolsta.

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.

The most common side effects of Rezolsta include:

  • Headache, abnormal dreams, muscle pain, muscle cramps or weakness, osteonecrosis (death of bone tissue caused by loss of blood supply to the bone), diabetes and tiredness.
  • Diarrhoea and nausea, vomiting, pain or swelling of the belly, indigestion, flatulence, decreased appetite.
  • Allergic reactions such as rash, itching, swelling of the skin and other tissues (most often the lips or the eyes).

A common side effect of Rezolsta 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 Rezolsta.

People with HIV may gain weight after starting treatment. Combinations containing darunavir have been shown to lead to modest weight gain.

Does Rezolsta 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.

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

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

  • alfuzosin
  • amiodarone
  • astemizole
  • avanafil
  • bepridil
  • carbamazepine
  • cisapride
  • colchicine
  • dronedarone
  • ergot alkaloids (ergotamine, dihydroergotamine, ergometrine, methylergonovine)
  • lidocaine
  • lovastatin
  • midazolam
  • phenobarbital
  • phenytoin
  • pimozide
  • quetiapine
  • quinidine
  • ranolazine
  • rifampicin
  • sertindole
  • sildenafil
  • simvastatin
  • St John’s wort
  • terfenadine
  • ticagrelor
  • triazolam.

Can I take Rezolsta in pregnancy?

Rezolsta is not recommended for women during 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.

Can children take Rezolsta?

Rezolsta 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.


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.

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.

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. 



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.


Any perceptible, subjective change in the body or its functions that signals the presence of a disease or condition, as reported by the patient.


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 Rezolsta page in the A-Z of antiretroviral medications.

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