Lamivudine and zidovudine are medications used to treat HIV. They are antiretroviral drugs combined in one tablet. The usual adult dose is one tablet taken twice a day along with another antiretroviral drug.

The pill combines 150mg lamivudine and 300mg zidovudine. This combination is sometimes marketed under the brand name Combivir, but generic versions are also available and these are more commonly used.

Lamivudine and zidovudine are from a class of drugs known as NRTIs (nucleoside reverse transcriptase inhibitors).

Your doctor will prescribe lamivudine/zidovudine as part of your HIV treatment, along with an antiretroviral 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 lamivudine/zidovudine twice a day, with some water. You can take it with or without food.

If you find it hard to swallow the pills whole, you can crush them and take them with a small amount of food or drink. Be careful if you do this and make sure that you take the whole dose.

Ideally, you should leave 12 hours between doses and take the doses at regular times each day.

HIV treatment works best if you take it every day. If you forget to take a dose of lamivudine/zidovudine, take it as soon as you remember. If it’s nearly time to take 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 lamivudine/zidovudine.

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 lamivudine/zidovudine are (most common in bold):

Nausea, headache, vomiting, diarrhoea, abdominal pain, loss of appetite, tiredness, dizziness, fever, insomnia (difficulty sleeping), joint or muscle pain, cough, runny nose, hair loss, rash, fat loss, anaemia, low white blood cell count, raised liver enzymes.

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

You should not take lamivudine/zidovudine with any of the following drugs:

• clabribine
• high doses of cotrimoxazole
• emtricitabine
• ganciclovir injections
• other medicines containing lamivudine
• ribavirin.

There are other interactions, including with drugs used to treat epilepsy, malaria, cancer, gout, and infections and with methadone, used as a heroin substitute, so it is very important that you tell your doctor about other drugs you are taking.

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.

The British HIV Association (BHIVA) recommends that women who are already taking anti-HIV medications and become pregnant can usually continue to take the same medication throughout their pregnancy. In addition, BHIVA lists lamivudine/zidovudine (in combination with one or two other drugs) as an option that may be considered for women who start HIV treatment in pregnancy, depending on their individual circumstances.

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

Lamivudine/zidovudine can be taken by children weighing 14kg or more. Tablets will be split for children weighing 14-30kg.

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