Darunavir is a medication used to treat HIV. It is marketed under the brand name Prezista, but generic versions are also available. It is taken in combination with other antiretroviral drugs.

The usual adult dose of darunavir is 800mg taken once a day, with a booster drug. This can be taken as one red 800mg tablet taken with one 100mg ritonavir tablet (a booster drug). Alternatively, the combination pill Rezolsta contains 800mg darunavir and 150mg cobicistat (a booster drug).

If you have a type of HIV which is resistant to some drugs, your doctor may prescribe a different dose, made up of one 600mg tablet plus one 100mg ritonavir tablet taken together twice a day.

Darunavir is also available in a combination tablet called Symtuza, which contains 800mg darunavir, 200mg emtricitabine and 10mg tenofovir alafenamide, along with 150mg cobicistat.

Darunavir is from a class of drugs known as protease inhibitors. Your doctor will prescribe darunavir as part of your HIV treatment, along with a booster drug and 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.

You should take darunavir with a meal or a snack to help your body absorb the drug.

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 take your treatment.

If you forget to take a dose of darunavir, take it as soon as you remember with food. If it is less than 12 hours until your next dose 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.

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 darunavir.

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 darunavir include (most common in bold):

• Diarrhoea, vomiting, nausea, abdominal pain, bloating, indigestion, flatulence.
• Headache, tiredness, dizziness, drowsiness, numbness, peripheral neuropathy (damage to nerves in the hands or feet causing tingling or pain), difficulty in sleeping, weakness.
• Rash, itching, diabetes, raised lipids, raised liver enzymes.

You should always tell your doctor and pharmacist about any other drugs or medication you are taking. That includes anything prescribed by another doctor, medicines you have bought from a high-street chemist, herbal and alternative treatments, and recreational or party drugs (‘chems’).

Some medicines or drugs are not safe if taken together – the interaction could cause increased, dangerous levels, or it could 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. This must only be done on the advice of your HIV doctor.

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

You should not take darunavir with any of the following medicines:

• alfuzosin
• amiodarone
• astemizole
• avanafil
• bepridil
• cisapride
• colchicine (if you also have kidney or liver problems)
• dihydroergotamine
• dronedarone
• elbasvir/grazoprevir
• ergometrine
• ergotamine
• lopinavir/ritonavir
• lovastatin
• lurasidone
• methylergonovine
• midazolam (oral)
• pimozide
• quetiapine
• quinidine
• ranolazine
• rifampicin
• sertindole
• sildenafil (when used to treat pulmonary arterial hypertension)
• simvastatin
• St John’s wort
• systemic lidocaine
• terfenadine
• ticagrelor
• triazolam.

If you are taking darunavir, it is particularly important to check with your HIV doctor or pharmacist before taking other medicines, as these may interact with darunavir or with the boosting drugs ritonavir or cobicistat.

Some common drugs may be affected, including antibiotics, corticosteroids, hormonal contraceptives, metformin, methadone and statins.

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.

Darunavir boosted with ritonavir may be considered an option in pregnancy, but it is important to talk to your doctor. For example, it may be necessary to adjust the dose.

The British HIV Association (BHIVA) recommends darunavir boosted with ritonavir (in combination with other medications) as a medication that may be provided to women who start HIV treatment in pregnancy, depending on their individual circumstances.

Darunavir boosted with cobicistat is not recommended during pregnancy.

Darunavir is approved for use in children. Prezista oral solution or reduced dose tablets are available.

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.

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. Our online tool Talking points may help you to prepare for your next appointment – visit www.aidsmap.com/talking-points 

For detailed information on this drug, visit the darunavir pages in the A-Z of antiretroviral drugs.