What is Odefsey?

Odefsey is a medication used to treat HIV. It is a combination of three separate antiretroviral drugs in one pill, taken once a day.

It combines 25mg rilpivirine, 200mg emtricitabine and 25mg tenofovir alafenamide in a grey, capsule-shaped, film-coated tablet. The tablet has ‘GSI’ on one side and ‘255’ on the other side.

How does Odefsey work?

Odefsey combines three antiretroviral drugs in one pill. Two of the drugs (emtricitabine and tenofovir alafenamide) are from a class of drugs known as NRTIs (nucleoside/nucleotide reverse transcriptase inhibitors). The third drug, rilpivirine, is a non-nucleoside reverse transcriptase inhibitor (NNRTI). Each drug class works against HIV in a different way.

The aim of HIV treatment is to reduce the level of HIV (the ‘viral load’) in your body until 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 Odefsey?

You should take Odefsey once a day with food. The tablet should be swallowed whole; do not chew, crush or split it.

HIV treatment works best if you take it every day, ideally at the same time each day. It may help to set an alarm, e.g. on your mobile phone, to remind you. If you forget to take a dose of Odefsey and realise within 12 hours of the time you usually take it, take it as soon as possible with food, then take your next dose at your usual time. If you realise more than 12 hours late, don’t take a double dose, just skip the dose you’ve forgotten and then carry on with your normal routine.

If you are sick (vomit) within 4 hours of taking your Odefsey tablet you should take another tablet with food; if you vomit more than 4 hours after your dose there is no need to repeat the dose.

What are the possible side effects of Odefsey?

All medicines have possible side effects. It’s a good idea to talk to a doctor, nurse or pharmacist about what to expect before you start taking any medication, and how to manage any side effects which occur.

A full list of side effects, including less common side effects, can be found in the patient information leaflet that comes with Odefsey.

Side effects can be described as:

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 Odefsey include (most common in bold):

Difficulty sleeping, headache, dizziness, feeling sick, decreased appetite, depression, abnormal dreams, depressed mood, feeling sleepy, tiredness, stomach pain or discomfort, being sick, feeling bloated, dry mouth, wind (flatulence), diarrhoea and rash, low white or red blood cell count, low platelet count, raised lipid or pancreatic enzyme  or liver enzyme levels.

People with HIV may gain weight after starting antiretroviral treatment. People taking Odefsey may gain a modest amount of weight. Women, people with low CD4 counts and people with higher body mass are more likely to gain weight than others.

Does Odefsey interact with other drugs?

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.

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.

You should not take Odefsey if you are currently taking medicines from the following groups:

  • carbamazepine, oxcarbazepine, phenobarbital and phenytoin (used to treat epilepsy and prevent seizures)
  • rifabutin, rifampicin and rifapentine (used to treat some bacterial infections such as tuberculosis)
  • omeprazole, dexlansoprazole, lansoprazole, rabeprazole, pantoprazole and esomeprazole (used to prevent and treat stomach ulcers, heartburn, acid reflux disease)
  • dexamethasone (a corticosteroid medicine used to treat inflammation and suppress the immune system)
  • products that contain St John’s wort (a herbal remedy used for depression and anxiety).

Odefsey needs an acidic environment in the stomach to be absorbed – any medication used to reduce stomach acid or treat indigestion or heartburn could reduce levels of Odefsey and must be used with caution:

  • antacids should be taken at least 2 hours before or at least 4 hours after Odefsey
  • H2 receptor antagonists should be taken only once a day, at least 12 hours before or at least 4 hours after Odefsey.

Always check with your HIV doctor or pharmacist before taking any treatment for stomach acid or indigestion.

The patient information leaflet which comes with your Odefsey has a full list of medicines which should be avoided, but it is important to talk to your doctor about any other medicines you are taking.

Can I take Odefsey in pregnancy?


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.

drug interaction

A risky combination of drugs, when drug A interferes with the functioning of drug B. Blood levels of the drug may be lowered or raised, potentially interfering with effectiveness or making side-effects worse. Also known as a drug-drug interaction.

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. 


non-nucleoside reverse transcriptase inhibitor (NNRTI)

Non-nucleoside reverse transcriptase inhibitor, the family of antiretrovirals which includes efavirenz, nevirapine, etravirine, doravirine and rilpivirine. Non-nucleoside reverse transcriptase inhibitors (NNRTIs) bind to and block HIV reverse transcriptase (an HIV enzyme), preventing HIV from replicating.

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.

Odefsey is not usually used by women who are pregnant or want to get pregnant as it has not been studied in women who are pregnant. For this reason, the British HIV Association (BHIVA) does not recommend its use in pregnancy.

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. Odefsey should not be used during breastfeeding as at least one of the drugs it contains passes into breast milk.

Can children take Odefsey?

Odefsey can be taken by children aged 12 years and over, weighing 35kg or more.

Talking to your doctor

If you have any concerns about your treatment or other aspects of your health, it’s important to talk about these. For example, if you have any symptom or side effect which may be from your treatment, or if you are finding it difficult to take your medication every day, one of your healthcare team will be able to help.

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.

Next review date