Most people now take these drugs in a fixed-dose pill that combines a number of drugs. These combination pills are listed first and there are also separate entries on the individual drugs.

This is a combination of AZT (zidovudine) and 3TC (lamivudine). The dosage is one white tablet (150mg 3TC and 300mg AZT) twice a day.

Side-effects: Most commonly, nausea, vomiting, diarrhoea, tiredness, headache, dizziness, weakness, muscle pain, loss of appetite, fever, abdominal pain, hair loss, insomnia, rash, runny nose, joint pain. See the entries on AZT and 3TC (below) for more detail.

Tips on taking it: One tablet twice a day with or without food.

Key drug interactions: See the entries on AZT and 3TC below.

This drug combines 3TC (lamivudine) and abacavir. The dosage of Kivexa is one orange tablet (600mg abacavir and 300mg 3TC) once a day.

Side-effects: Abacavir can cause a serious hypersensitivity reaction. This is associated with the presence of a particular gene. Before starting treatment with Kivexa (or any treatment that contains abacavir) you should have an HLA-B*5701 test to see if you have this gene. If the test is positive you must not take Kivexa. If the test is negative, it is highly unlikely that an allergic reaction will occur, but contact your HIV clinic immediately (or A&E if out of hours) if you begin to feel unwell after starting the drug.

In the box with the drug there is an ‘alert card’, which you should carry with you for the first six weeks of taking Kivexa. The particular side-effects you should look out for during this time are:

Any skin rash OR

If you get one or more symptoms from at least TWO of the following groups:

• fever
• shortness of breath, sore throat or cough
• nausea or vomiting, or diarrhoea or abdominal pain
• severe tiredness or achiness or generally feeling ill.

Other side-effects include nausea, vomiting, diarrhoea, headache, abdominal pain, hair loss, fever, insomnia, rash, tiredness, loss of appetite, runny nose and joint pain.

See the entries on 3TC and abacavir (below) for more detail.

Tips on taking it: Take one tablet, once a day, with or without food.

Key drug interactions: See the entries for 3TC and abacavir below.

This drug combines 3TC (lamivudine), abacavir and AZT (zidovudine). The dose is one green tablet (300mg AZT, 150mg 3TC and 300mg abacavir) taken twice a day.

Treatment with Trizivir is not generally recommended. By itself, its anti-HIV effect is often not strong enough to suppress viral load to undetectable levels. Furthermore, as it contains AZT, which has been shown to cause lipoatrophy, it should not be used if other treatment options are available.

Side-effects: Abacavir can cause a serious hypersensitivity reaction. This is associated with the presence of a particular gene. Before starting treatment with Trizivir (or any treatment that contains abacavir) you should have an HLA-B*5701 test to see if you have this gene. If the test is positive you must not take Trizivir. If the test is negative, it is highly unlikely that an allergic reaction will occur, but contact your HIV clinic immediately (or A&E if out of hours) if you begin to feel unwell after starting the drug.

In the box with the drug there is an ‘alert card’, which you should carry with you for the first six weeks of taking Trizivir. The particular side-effects you should look out for during this time are:

Any skin rash OR

If you get one or more symptoms from at least TWO of the following groups:

• fever
• shortness of breath, sore throat or cough
• nausea or vomiting, or diarrhoea or abdominal pain
• severe tiredness or achiness or generally feeling ill.

Other side-effects include nausea, vomiting, diarrhoea, headache, abdominal pain, hair loss, fever, insomnia, rash, tiredness, runny nose, joint pain, weakness, muscle pain and loss of appetite.

See the entries on 3TC, abacavir and AZT (below) for more detail.

Tips on taking it: Take one tablet twice a day, with or without food.

Key drug interactions: See the entries for 3TC, abacavir and AZT below.

FTC and tenofovir are combined in this pill. The dose is one blue tablet (200mg FTC and 245mg tenofovir) once a day.

Side-effects: Nausea, vomiting, diarrhoea, dizziness, headache, rash, weakness, stomach pains, fatigue, bloating, flatulence, raised creatine kinase levels, low blood phosphate levels and skin darkening. See the entries for FTC and tenofovir (below) for more detail.

Tips on taking it: Take once a day, preferably with food, although you can take Truvada on an empty stomach.

Key drug interactions: See the entries for FTC and tenofovir below.

Names: 3TC, lamivudine, Epivir 

Approved dosage: 300mg daily, as one white 150mg tablet twice a day, or two white 150mg tablets once a day, or one larger, grey 300mg tablet once a day. Also available in a combined form with AZT called Combivir, in a combined form with AZT and abacavir called Trizivir, and in a combined form with abacavir called Kivexa.

Children: Approved for use in children. Liquid suspension available. 

Tips on taking it: Take with or without food. 

Common side-effects: Nausea, vomiting, diarrhoea, headache, abdominal pain, hair loss, fever, insomnia, rash, tiredness and joint pain.

Rare side-effects: Lactic acidosis, liver damage.

Key drug interactions: 3TC should not be used with the anti-HIV drug FTC. 3TC should not be taken with high doses of the antibiotic cotrimoxazole.

Names: Abacavir, Ziagen 

Approved dosage: 600mg daily, either as one 300mg yellow tablet twice daily or two 300mg tablets once a day. Abacavir and 3TC are available in a combined formulation called Kivexa. Abacavir is also available in a combined form with AZT and 3TC called Trizivir.

Children: Liquid formulation available. 

Tips on taking it: Take with or without food. 

Common side-effects: Nausea, vomiting, diarrhoea, fever, headache, abdominal pain, tiredness and loss of appetite.

Rare side-effects: Hypersensitivity reaction, lactic acidosis. Some, but not all, research has linked abacavir with an increased risk of heart attack. For this reason, abacavir is not recommended if you have other risk factors for heart disease. Your doctor will discuss this with you.

Important warning: Abacavir can cause a serious hypersensitivity reaction. This is associated with the presence of a particular gene. Before starting treatment with abacavir (or any treatment that contains abacavir) you should have an HLA-B*5701 test to see if you have this gene. If the test is positive you must not take abacavir. If the test is negative, it is highly unlikely that an allergic reaction will occur, but contact your HIV clinic immediately (or A&E if out of hours) if you begin to feel unwell after starting the drug.

In the box with the drug there is an ‘alert card’, which you should carry with you for the first six weeks of taking abacavir. The particular side-effects you should look out for during this time are:

Any skin rash OR

If you get one or more symptoms from at least TWO of the following groups:

• fever
• shortness of breath, sore throat or cough
• nausea or vomiting, or diarrhoea or abdominal pain
• severe tiredness or achiness or generally feeling ill.

You should never retry abacavir, or take Trizivir or Kivexa, if you have had an allergic reaction to abacavir previously.

Key drug interactions: Care should be taken when abacavir is taken with ribavirin, used to treat hepatitis C. Phenytoin, used to treat epilepsy, may also interact with abacavir.

Names: AZT, zidovudine

Approved dosage: AZT is available as a generic drug, so its appearance will depend on which type your clinic buys.

The approved dose is one 250mg capsule taken twice a day. A 100mg capsule is available for dose variations. Also available in a combined tablet with 3TC called Combivir and in a combined tablet with 3TC and abacavir, called Trizivir.

Children: Approved for use in children. Liquid formulation available. 

Tips on taking it: Can be taken with or without food, but taking with food reduces nausea.

Common side-effects: Nausea, vomiting, fatigue, headache, dizziness, weakness, muscle pain, loss of appetite, fever.

Rare side-effects: Blood disorders, lipoatrophy, lactic acidosis.

Key drug interactions: Do not take with the anti-HIV drug tipranavir. Close monitoring or dose adjustment needed if taking with the antibiotic clarithromycin or phenytoin, a drug used to treat epilepsy. Several other types of drugs, when taken with AZT, can cause an increase in side-effects, so it is important to talk to your doctor about any other drugs you are taking. These include, but are not limited to, methadone and drugs to treat infections, cancer and malaria.

Names: FTC, emtricitabine, Emtriva 

Approved dosage: One blue and white 200mg capsule once a day. FTC is also available in a combination tablet with tenofovir called Truvada, in a combination tablet with tenofovir and efavirenz called Atripla, and in a combination tablet with rilpivirine and tenofovir called Eviplera.

Note: People who have kidney abnormalities may be advised by their doctor to take a lower dose. 

Children: Approved for use by children aged four months and over. 

Tips on taking it: Can be taken with or without food. In the UK and Europe, it is recommended that Atripla should be taken on an empty stomach. Some people find taking it with food reduces side-effects, but avoid taking it with a high-fat meal; this may increase absorption of the drug, potentially increasing side-effects. Eviplera should always be taken with food.

Common side-effects: Nausea, diarrhoea, headache, raised creatine kinase levels, skin darkening.

Rare side-effects: Lactic acidosis, liver damage.

Key drug interactions: FTC should not be used with the anti-HIV drug 3TC (lamivudine).

Names: Tenofovir, Viread 

Approved dosage: One blue 245mg tablet daily. Dose may be adjusted if kidney function impaired. Also available in a combination tablet with FTC called Truvada, in a combination tablet with FTC and efavirenz called Atripla, and in a combination tablet with rilpivirine and FTC called Eviplera.

Tips on taking it: Take with food, to increase absorption. However, recommendations in the US say the drug can be taken with or without food. In the UK and Europe, it is recommended that Atripla should be taken on an empty stomach. Some people find taking it with food reduces side-effects, but avoid taking it with a high-fat meal; this may increase absorption of the drug, potentially increasing side-effects. Eviplera should always be taken with food.

Common side-effects: Nausea, vomiting, diarrhoea, flatulence, dizziness, low blood phosphate levels, weakness, rash, headache, stomach pains, fatigue and bloating.

Rare side-effects: Kidney problems, bone thinning.

Key drug interactions: Taking tenofovir and atazanavir together decreases the concentration of atazanavir, so it should only be used if boosted with ritonavir. Protease inhibitors also increase concentration of tenofovir, so if taken together your healthcare team should monitor you carefully for side-effects.

Do not take tenofovir at the same time as the anti-hepatitis drug adefovir dipivoxil (Hepsera).

It’s important your doctor knows about any other drugs you are taking in case they increase your risk of kidney problems. This includes creatine supplements used to increase exercise performance, as they can interfere with the results of kidney function blood tests. Make sure you tell your doctor if you are taking creatine, and don’t take it for two days before any blood tests.