Names: Efavirenz, EFV

Approved dosage: Efavirenz is available as a generic drug, so its appearance will depend on which type your clinic dispenses. Efavirenz typically comes as 600mg tablets or 200mg capsules. Efavirenz is also available in a combination tablet with emtricitabine and tenofovir disoproxil (Atripla).

Tips on taking it: Take one tablet once daily 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 the dose before going to bed can help reduce or prevent these side-effects.

Common side-effects: Rash, itching, dizziness, headache, abnormal dreams, anxiety, depression, difficulty sleeping, disturbed concentration, diarrhoea, nausea, vomiting, abdominal pain, tiredness and raised triglyceride and liver enzyme levels.

Mood and sleep problems 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 mental health problems, or have had in the past, efavirenz may not be a good choice for you. Talk to your doctor about other treatment options.

Rare side-effects: Severe rash, psychosis, suicidal feelings, liver failure.

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

Children: Approved for use in children aged 3 months and over.

Key drug interactions: Some drugs can interact with efavirenz and cause dangerous side-effects. Some examples are ergot alkaloids (used to treat migraine and cluster headaches and to control labour); midazolam (an anaesthetic); 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 antiretroviral drugs ritonavir-boosted darunavir, lopinavir/ritonavir (Kaletra), ritonavir, ritonavir-boosted atazanavir 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 barrier method or a different type of contraception.

Names: Etravirine, ETR, Intelence

Approved dosage: 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 either once or twice daily with food. If you find it difficult to take the tablet 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: Anaemia, low platelet count, diabetes, raised blood sugar, triglyceride or cholesterol levels, anxiety, difficulty in sleeping, headache, heart attack, high blood pressure, indigestion and acid reflux, diarrhoea, nausea, vomiting, flatulence, abdominal pain, kidney failure, tiredness, rash, peripheral neuropathy (damage to nerves in the hands or feet).

Rare side-effects: Severe rash, including Stevens-Johnson syndrome, a life-threatening allergic (hypersensitivity) reaction. 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, 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 may work for people whose HIV has resistance to other NNRTIs.

Children: Approved for use in children aged 6 years and over.

Key drug interactions: Do not take with the antiretroviral drugs atazanavir/ritonavir, and 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, 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 discuss this with your doctor who might recommend using an additional or different type of contraception.

Names: Nevirapine, NVP, Viramune prolonged-release

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

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 relating to the liver.

The recommended dose is one 200mg tablet once a day for the first two weeks and then one 200mg tablet twice a day thereafter.

Alternatively, you may be prescribed one 400mg tablet of once-daily prolonged-release formulation (Viramune prolonged-release or a generic product). 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.

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

Common side-effects: Allergic (hypersensitivity) reaction, headache, rash (usually in the first six weeks of treatment), fatigue, abdominal pain, diarrhoea, nausea, vomiting, fever, raised liver enzymes and high blood pressure.

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, nausea, vomiting, loss of appetite, or pain, aching or sensitivity on your right side below your ribs). If you develop these symptoms while taking this drug, you should contact your HIV clinic immediately (or A&E if out of hours). Liver toxicity is a rare life-threatening side-effect, usually occurring 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.

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

Children: Syrup available.

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 antiretroviral drugs atazanavir, lopinavir/ritonavir (Kaletra) 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, RPV, Edurant

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

Tips on taking it: Take one tablet once daily. Always take with food, such as your main meal of the day, otherwise you will not absorb enough rilpivirine and your treatment may fail. Rilpivirine is very small, so may be a good option if you have difficulty swallowing tablets.

Common side-effects: Insomnia, headache, nausea, rash, depression, dizziness, abdominal pain, vomiting, reduced white or red blood cell count, low platelet count, raised cholesterol or triglyceride or liver enzymes or pancreatic amylase or lipase levels, reduced appetite, difficulty in sleeping, abnormal dreams, low mood, tiredness, drowsiness, dry mouth.

Rare side-effects: Severe rash and allergic (hypersensitivity) reaction.

Children: Edurant is approved for use in children aged 12 years and over.

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, lansoprazole or pantoprazole. Indigestion remedies called H2-blockers (such as ranitidine, Zantac) should be taken at least 12 hours before or at least four hours after taking rilpivirine. If you are taking other indigestion remedies (such as Rennies or Gaviscon) or calcium supplements, they should be taken at least two hours before or at least four hours after taking rilpivirine as they can prevent it being absorbed properly.