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.

Atripla provides a complete HIV combination treatment in one pill, taken once a day. It combines 200mg of FTC, 300mg of tenofovir and 600mg of the non-nucleoside reverse transcriptase inhibitor efavirenz. The dose is one pink oval tablet a day.

Side-effects: Nausea and diarrhoea; mood and sleep disturbances (due to efavirenz); headache; changes in kidney function (due to tenofovir). Most people notice these side-effects soon after starting treatment. They often lessen or go away after the first few weeks of treatment. Your doctor will be able to give you some medicines to help control these.

Rarer side-effects include changes in your bone metabolism and kidney function (both possibly caused by tenofovir). You’ll be monitored for these as part of your routine HIV care.

Tips on taking it: Take once a day. In the UK and Europe it is recommended that Atripla should be taken on an empty stomach. Many people take this drug at bedtime.

Resistance: Resistance to efavirenz usually causes resistance to another NNRTI called nevirapine. However, a newer NNRTI, etravirine, is still likely to be effective.

Key drug interactions: Antibiotics – close monitoring or dose adjustment needed if taking with clarithromycin, rifabutin or rifampicin.

Antihistamines – do not take with astemizole or terfenadine.

Erectile dysfunction drugs – dose adjustment needed.

Lipid-lowering drugs – close monitoring or dose adjustment needed if taking with atorvostatin, pravastatin or simvastatin.

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

Side-effects: Nausea and diarrhoea; headache; lipoatrophy, a type of fat loss caused by AZT; for this reason, use of Combivir is not recommended if you have other options available. A rare, but possible, side-effect of 3TC is nerve damage in the feet, lower legs, and hands. AZT can also cause anaemia.

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

Key drug interactions: Antibiotics – close monitoring or dose adjustment needed if taking with clarithromycin, dapsone, rifampicin or cotrimoxazole (Septrin).

This drug combines 3TC 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 probably safe to take Kivexa, but tell your doctor immediately if you develop a rash, fever or headache.

Other side-effects include nausea and diarrhoea; headache; tiredness. Some, but not all, research has linked abacavir with an increased risk of heart attack. For this reason, abacavir might not be a good choice if you have other risk factors for heart disease.

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

Key drug interactions: Antibiotics – close monitoring or dose adjustment needed if taking with rifampicin or cotrimoxazole (Septrin).

Hepatitis C treatment – abacavir may result in reduced levels of ribavirin (a drug used to treat hepatitis C infection).

This drug combines 3TC, abacavir and AZT. 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: See the entries on 3TC, abacavir and AZT. 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.

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.

FTC and tenofovir are combined in this pill. The dose is one blue tablet (200mg FTC and 300mg tenofovir) once a day.

Side-effects: See the entries for FTC and tenofovir.

Tips on taking it: Take once a day. Taking with food increases absorption.

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

Names : 3TC, lamivudine, Epivir 

Approved dosage : 300mg daily, as one white 150mg tablet twice a day, two white 150mg tablets once a day or one larger, grey 300mg tablet once a day. The dose may be altered if you have impaired kidney function. Also available in a combined form with AZT called Combivir and in a combined form with AZT and abacavir called Trizivir. 3TC and abacavir are also available in a combined formulation called Kivexa. Combivir and Trizivir are both taken as one tablet twice a day and Kivexa is taken as one tablet once a day. 

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

Tips on taking it : Take with or without food. 

Common side-effects : Nausea, headache, tiredness, diarrhoea, abdominal pain and rash.

Rare side-effects: A rare, but possible, side-effect of 3TC is nerve damage in the feet, lower legs and hands.

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 also available in a combined formulation called Kivexa. The combined Kivexa pill contains 600mg of abacavir and 300mg of 3TC and the dose is one tablet, taken once daily. Also available in a combined form with AZT and 3TC called Trizivir, taken as one tablet twice daily.

Children : Liquid formulation available. 

Tips on taking it : Take with or without food. 

Common side-effects : Nausea and vomiting, diarrhoea, and headache.

Important warning: An allergic reaction (often involving fever and rash) occurs in approximately 5% of people taking abacavir, usually within four weeks of starting the drug. See your doctor immediately if you develop a rash, fever, shortness of breath or abdominal pain while on abacavir. You should never retry abacavir, or take Trizivir or Kivexa if you have had an allergic reaction to abacavir previously. Your clinic should conduct a genetic test (called a HLA-B*5701 test) to see if you are likely to have an allergic reaction to abacavir. If this test is positive you must not take abacavir. If it is negative, it is highly unlikely that an allergic reaction will occur, but you should still report symptoms like a fever, rash or headache to your doctor immediately. 

Key drug interactions : Abacavir may result in reduced levels of ribavirin (a drug used to treat hepatitis C infection).

Names : AZT, zidovudine, Retrovir 

Approved dosage : One white and blue 250mg capsule taken twice a day. A 100mg capsule is available for dose variations. Also available in a combined tablet with 3TC called Combivir, taken twice a day, and in a combined tablet with 3TC and abacavir, called Trizivir, taken twice a day.

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

Tips on taking it : Take with or after food to reduce nausea.

Common side-effects : Nausea, dizziness, vomiting, diarrhoea, muscle aches and headache. Lipoatrophy, a type of fat loss, may be a long-term side-effect of AZT. For this reason treatment with AZT is not recommended if you have other treatment options available to you.

Key drug interactions: Do not take with d4T. Drug levels may be affected if methadone, phenytoin or probenecid are taken with AZT. Doses of clarithromycin and AZT should be taken one hour apart.

Names : d4T, stavudine, Zerit, Zerit PRC 

Approved dosage : For people over 60kg (9½ stone): one dark orange 40mg capsule twice a day; for people under 60kg: usually one light and dark orange 30mg capsule twice a day. Note: people with impaired kidney function or peripheral neuropathy may take 15 or 20mg twice a day. d4T is available as 40mg, 30mg, 20mg and 15mg capsules.

Children : Approved for use in children. d4T comes in a powder form which is made into a liquid. 

Tips on taking it : Although the product information advises taking d4T on an empty stomach, this does not affect absorption of the drug and it is possible to take with or without food. However, taking it with food reduces nausea. 

Common side-effects : Peripheral neuropathy, headache, nausea, diarrhoea or constipation, lipodystrophy, fatigue, depression and rash. Fat loss (lipoatrophy) has been recognised as a long-term side-effect of d4T. For this reason d4T is not recommended if you have other treatment options available to you.

Rare side-effects include : Pancreatitis and liver problems. 

Key drug interactions : Do not take with AZT or ddI. Drugs that may cause peripheral neuropathy or pancreatitis (e.g. ddI) may increase the risk of these side-effects. 

ddI is available in two formulations, as a tablet and capsule. Advice on taking ddI differs depending upon which formulation you are taking, so it is very important to check that you are following the advice that relates to the form you are taking. 

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. This is taken once a day and consists of 200mg of FTC and 300mg of tenofovir. Also in a combination tablet with tenofovir and efavirenz called Atripla. This is taken once a day and consists of 200mg of FTC, 300mg of tenofovir and 600mg of efavirenz. 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. Atripla should be taken on an empty stomach.

Common side-effects : Headache, diarrhoea, nausea and rash.

Names : Tenofovir, Viread 

Approved dosage : One blue, pear-shaped film-coated 300mg tablet daily. Dose may be adjusted if kidney function impaired. Also available in a combination tablet with FTC called Truvada. This is taken once a day and consists of 300mg of tenofovir and 200mg of FTC. Also in a combination tablet with FTC and efavirenz called Atripla. This tablet is taken once a day and consists of 300mg of tenofovir, 200mg of FTC and 600mg of efavirenz.

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. Atripla should be taken on an empty stomach.

Common side-effects : Nausea, diarrhoea, flatulence, dizziness and vomiting.

Rare side-effects: Changes in bone metabolism and kidney function. You’ll be monitored for these as part of your routine HIV care.

Key drug interactions : Tenofovir increases levels of ddI. Should only be used with atazanavir if it is boosted by ritonavir.