Indications
Efavirenz is an antiretroviral medicine used together with other HIV medicines to treat HIV-1 infection in adults and children. It is never used alone, because the virus can quickly become resistant.
How It Works
HIV needs an enzyme called reverse transcriptase to copy itself inside human cells. Efavirenz binds to this enzyme and blocks it, which lowers the amount of virus in the blood and allows the immune system to recover. It does not cure HIV but keeps it under control when taken every day.
Dosage and Administration
Take exactly as prescribed. For adults the usual dose is 600 mg once a day, taken on an empty stomach, preferably at bedtime to make dizziness and sleep problems easier to cope with. Children’s doses depend on body weight and are set by the doctor. Do not miss doses or stop treatment without medical advice.
Interactions
- Efavirenz changes liver enzymes and interacts with many medicines, including other HIV medicines, Rifampicin, some antifungals such as Voriconazole, Methadone, Warfarin, some statins and anti-seizure medicines.
- It can lower the effect of hormonal contraceptives and implants: use a barrier method as well.
- St John’s Wort must be avoided.
- Alcohol and other medicines that affect the brain may increase dizziness or mood effects.
Contraindications
- Allergy to efavirenz.
- Severe liver disease.
- Use with certain medicines that interact dangerously, as listed by the doctor (for example some ergot medicines, Voriconazole at standard doses, St John’s Wort).
Side Effects
Common effects include dizziness, unusual or vivid dreams, trouble sleeping or sleepiness, poor concentration, headache, rash, nausea and diarrhoea. Nervous system effects are usually worst in the first 2 to 4 weeks. Cholesterol and liver enzymes may rise.
Get urgent medical help for a severe or blistering rash, yellow skin or eyes, seizures, severe depression, thoughts of self-harm, confusion or strange behaviour, or signs of a severe allergic reaction.
Pregnancy and Lactation
Women who can become pregnant should discuss contraception and pregnancy plans with their doctor before and during treatment; current HIV guidelines decide which regimen is best in pregnancy. Do not stop HIV treatment without advice. Breastfeeding advice for mothers with HIV depends on local guidelines: ask your doctor.
Precautions and Warnings
- May cause dizziness and poor concentration: avoid driving if affected.
- Tell the doctor about any history of mental illness, seizures, liver disease or hepatitis B or C.
- Regular blood tests check viral load, liver function and cholesterol.
- Taking it with a heavy, fatty meal increases side effects.
Overdose
Overdose may cause stronger nervous system effects such as confusion and involuntary muscle movements. Seek medical help; treatment is supportive.
Therapeutic Class
Antiretroviral, non-nucleoside reverse transcriptase inhibitor (NNRTI).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.