Names: Efavirenz, Sustiva 

Approved dosage: One dark-yellow 600mg tablet once a day or three dark-yellow 200mg capsules once a day. Efavirenz is also available in a combination tablet with FTC and tenofovir (Atripla).

Children: Approved for use in children aged three years and above, who weigh more than 13kg. Oral solution available (but note that the dose of the solution is different from the dose of the tablets or capsules). 

Tips on taking it: Recommended to take 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. If efavirenz causes confusion or dizziness, taking before going to bed can help. 

Common side-effects: Rash, dizziness, headache, diarrhoea, nausea, vomiting and tiredness.

Efavirenz can cause mood and sleep problems. These are most commonly experienced during the first four weeks of treatment and include feeling ‘out of sorts’, confusion, impaired concentration, sleep disturbance, abnormal dreams, anxiety and depression. In most cases these side-effects go away by themselves and it isn’t necessary to stop taking efavirenz. However, some people find them intolerable and need to change treatment as a result. If you have a history of mental health problems, efavirenz may not be a good choice for you. Talk to your doctor about other treatment options. 

Rare side-effects: Severe rash, psychosis, liver problems. 

Resistance to efavirenz: Is likely to cause resistance to nevirapine and possibly to rilpivirine. 

Key drug interactions: Some drugs can interact with efavirenz and cause dangerous side-effects. Do not take efavirenz with the anti-hepatitis drug boceprevir; ergot alkaloids (used to treat migraine and cluster headaches and to control labour); midazolam (used to help you sleep); pimozide (used to treat certain mental health conditions); or St John's wort.

Some drugs can interact with efavirenz and change blood levels of one or both drugs, so dose adjustments may be needed. This is the case for the anti-HIV drugs darunavir, lopinavir/ritonavir (Kaletra), ritonavir, ritonavir-boosted atazanavir, fosamprenavir and maraviroc. This is also the case for some drugs used to treat bacterial infections such as TB (including clarithromycin, rifabutin and rifampicin), anti-fungal treatments, anticonvulsants, statins, methadone, sertraline, calcium channel blockers, immunosuppressants and warfarin.

Efavirenz may reduce the effectiveness of some hormonal contraceptives (such as the ‘pill’, patches or an implant). If you are using this type of contraceptive to prevent pregnancy you should use an additional or different type of contraception.

Names: Etravirine, Intelence.

Approved dose: One white 200mg tablet or two white 100mg tablets taken twice a day. Your doctor may recommend taking 400mg etravirine once a day. However, do not change to this dosage without consulting your doctor.  

Tips on taking it: Take with food. If you find it difficult to take the table whole, you can disperse it in a glass of water. Stir it well and drink it straight away. Add some more water and drink that too, to make sure you have taken the entire dose.

Common side-effects: Rash, peripheral neuropathy.

Rare side-effects: Severe rash, including Stevens Johnson syndrome. You should watch out for the following symptoms accompanying any rash if you are starting etravirine: fever, generally feeling ill, extreme tiredness, muscle or joint aches, blisters, oral lesions, eye inflammation, facial swelling and/or signs and symptoms of liver problems (e.g., yellowing of your skin or whites of your eyes, dark or tea-coloured urine, pale-coloured stools/bowel movements, nausea, vomiting, loss of appetite, or pain, aching or sensitivity on your right side below your ribs). If you develop these symptoms whilst taking this drug you should contact your HIV clinic immediately or A&E if out of hours.

Resistance: Etravirine can work in people whose HIV has resistance to other NNRTIs.

Key drug interactions: Do not take with the anti-HIV drugs fosamprenavir/ritonavir, atazanavir/ritonavir, protease inhibitors taken without ritonavir or other NNRTIs. It is not recommended to take etravirine with some drugs used to treat epilepsy, rifampicin (an antibiotic used to treat infections, including TB), or St John’s wort.

When taken with the anti-HIV drug maraviroc and a protease inhibitor, a dose adjustment of maraviroc may be needed.

Some drugs can interact with etravirine and change blood levels of one or both drugs, so dose adjustments may be needed. It’s important your doctor knows about any other drugs you are taking, including drugs used to treat bacterial infections, including TB (clarithromycin, rifabutin), statins, drugs used to treat certain heart conditions, antifungal treatments, immunosuppressants, drugs used to treat erectile dysfunction, clopidogrel, dexamethasone, diazepam and warfarin.

Etravirine may reduce the effectiveness of hormonal contraceptives (such as the ‘pill’, patches or an implant). If you are using this type of contraceptive to prevent pregnancy you should use an additional or different type of contraception.

Names: Nevirapine, Viramune, Viramune prolonged-release

Approved dosage: Men should not start treatment with nevirapine if their CD4 cell count is above 400 and women should not start treatment with nevirapine if their CD4 cell count is above 250, as this increases the risk of potentially dangerous side-effects. 

One white 200mg tablet once a day for the first two weeks and then one 200mg tablet twice a day thereafter.

Alternatively, one 400mg yellow tablet of once-daily prolonged-release formulation (Viramune prolonged-release). People starting HIV treatment will take a 14-day lead-in dose of 200mg of immediate-release nevirapine in order to reduce the risk of rash, a common side-effect during the first few weeks of nevirapine treatment. Treatment with Viramune prolonged-release should not begin until the rash has gone away. Always tell your doctor about any rash you develop while taking nevirapine. If a rash persists for more than one month, or becomes more severe, an alternative drug should be used.

Children: Syrup available. 

Tips on taking it: Take with or without food. Viramune prolonged-release must be swallowed whole and not crushed, chewed or divided.

Common side-effects: Allergic reaction, headache, rash (usually in the first six weeks of treatment), fatigue, stomach pain, diarrhoea, nausea and liver toxicity (usually in the first six weeks of treatment). During the first 18 weeks of treatment with nevirapine, the health of your liver will be intensively monitored; you will be advised to have liver function tests every one to two weeks for the first six weeks. 

Rare side-effects: Severe rash (Stevens Johnson syndrome). Symptoms include: fever, generally feeling ill, extreme tiredness, muscle or joint aches, blisters, oral lesions, eye inflammation, facial swelling, signs and symptoms of liver problems (e.g., yellowing of your skin or whites of your eyes, dark or tea-coloured urine, pale-coloured stools/bowel movements, nausea, vomiting, loss of appetite, or pain, aching or sensitivity on your right side below your ribs).  If you develop these symptoms whilst taking this drug, you should contact your HIV clinic immediately (or A&E if out of hours).

Resistance to nevirapine: Is likely to cause resistance to efavirenz and possibly to rilpivirine. 

Key drug interactions: Do not take St John’s wort with nevirapine.

Some drugs interact with nevirapine and change blood levels of the drugs, which may stop them working or cause side-effects. These include the anti-HIV drugs atazanavir, lopinavir/ritonavir (Kaletra), fosamprenavir and efavirenz.

It’s also particularly important your doctor knows if you are taking any of the following drugs with nevirapine, so that the effects can be monitored: antibiotics used to treat certain infections, such as TB (including rifampicin, rifabutin and clarithromycin), anti-fungal treatments, methadone and warfarin.

Nevirapine may reduce the effectiveness of hormonal contraceptives (such as the ‘pill’, patches or an implant). If you are using this type of contraceptive to prevent pregnancy you should use an additional or different type of contraception.

Names: Rilpivirine, Edurant

Approved dosage: One white 25mg tablet taken once a day. Also available in a combination tablet with FTC and tenofovir (Eviplera).

Tips on taking it: Always take with a meal.

Common side-effects: Insomnia, headache, nausea, rash, raised liver enzymes, depression, dizziness, stomach pains, vomiting.

Rare side-effects: At doses above 25mg, changes in heart rhythm (known as QT prolongation).

Key drug interactions: It’s not recommended that rilpivirine be used in combination with other NNRTIs.

Do not take rilpivirine with the anticonvulsants carbamazepine, oxcarbazepine, phenobarbital or phenytoin or with St John’s wort. Rilpivirine should not be taken at the same time as the antibiotics rifampicin and rifabutin (often used to treat TB). Some other antibiotics can increase blood levels of rilpivirine.

Medicines that affect stomach acidity can block the way rilpivirine is absorbed. Don’t take proton pump inhibitors (PPIs), such as omeprazole. Indigestion remedies called H₂-blockers (such as ranitidine, Zantac) should be taken at least 12 hours before or at least four hours aftertaking rilpivirine.If taking other indigestion remedies or calcium supplements, they should be taken at least two hours before or at least four hours aftertaking rilpivirine as they can prevent it being absorbed properly.

It may be necessary to increase methadone doses when taken at the same time as rilpivirine.