Taking it

Efavirenz (Sustiva) is dosed at 600mg, taken in the form of three 200mg capsules or one 600mg tablet once a day. The drug should be taken on an empty stomach before going to bed in order to reduce the risk of side-effects. Taking the drug with food may increase drug levels in some people by up to 50%. High-fat meals may increase the absorption of efavirenz, which may in turn increase the risk of side-effects, especially during the early weeks of treatment.

US guidelines on efavirenz (EFV) dosing were revised in some areas in 2008:

  • EFV 600mg once daily with boosted fosamprenavir (FPV/r 700/100mg bid).
  • ARV-naive patients only: EFV 600mg + FPV/r at 1400/300mg, all once daily.
  • EFV 600mg with boosted atazanavir at 300/100mg, all once daily with food.
  • EFV 600mg once daily with indinavir 1000mg three times daily. 
  • EFV 600mg once daily with boosted lopinavir 600/150mg three times daily in 12 years and older. Check manufacturer's dosing tables to adjust LPV/r dose in children 6 months to 12 years.
  • EFV 600 mg with maraviroc 600mg, both once daily.
  • Use EFV with caution in patients with hepatic impairment. 

It is important to take the drug as prescribed in order to maintain the right level of the drug in the blood. If blood levels of the drug fall too low, this will help the development of resistance to efavirenz and may affect future treatment options.

Efavirenz is also available as a solution for use in children and people who cannot take the tablets or capsules.

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.