Efavirenz: What it does and how to take it safely

Efavirenz is an antiretroviral medicine used to treat HIV infection as part of combination therapy. It belongs to a class called non-nucleoside reverse transcriptase inhibitors (NNRTIs) and helps stop the virus from copying itself. Doctors usually prescribe efavirenz together with at least two other antiretroviral drugs so the virus can be controlled and resistance reduced.

The common adult dose is 600 mg once daily, often taken at bedtime. Taking efavirenz on an empty stomach or with a light snack lowers the chance of strong side effects, while high‑fat meals can increase blood levels and boost dizziness or vivid dreams. Never change the dose or stop efavirenz without talking to your healthcare provider — sudden stopping can let the virus rebound and raise the risk of resistance.

What to watch for

Efavirenz can cause side effects that affect mood and thinking. Many people notice dizziness, trouble sleeping, vivid dreams, or mood changes during the first few weeks. Most of these improve over time, but if you or someone close notices worsening depression, anxiety, or thoughts of harming yourself, contact a healthcare professional right away. Other common effects include rash and increased liver enzymes, so regular blood tests are usually recommended.

Efavirenz is processed by liver enzymes and interacts with many drugs. It can lower the effectiveness of hormonal birth control and change blood levels of other medicines processed by CYP enzymes. Tell your prescriber about every prescription drug, over‑the‑counter medicine, and supplement you take — especially statins, benzodiazepines, anticonvulsants, and certain heart medications. Your provider may need to adjust doses or choose different drugs.

Practical tips for daily use

Take efavirenz at the same time each night to build a routine and reduce daytime drowsiness. If you miss a dose and it’s less than 12 hours late, take it as soon as you remember; if more than 12 hours, skip it and take the next dose on schedule. Avoid driving or using heavy machinery until you know how efavirenz affects you. If you drink alcohol, be cautious — combining alcohol with efavirenz can worsen dizziness and mood changes.

Women who are pregnant, trying to get pregnant, or breastfeeding should discuss efavirenz with their clinician. Historically there were concerns about early pregnancy, but decisions now depend on the full clinical picture and alternative options. Always talk through risks and benefits with your care team.

Finally, efavirenz is prescription only. Buy it from licensed pharmacies, follow storage instructions on the label, and bring it to clinic visits so your healthcare team can monitor treatment progress. If cost or access is an issue, ask your clinic about assistance programs or generics that may be available.

Your clinic will check viral load and liver function regularly. Viral load tests show whether the drug is working. Bring a list of medicines to every visit. Store efavirenz at room temperature away from moisture. If you plan travel, pack in carry‑on and carry a copy of your prescription. Support groups and HIV clinics can help with adherence tips and cost help — ask your care team for local resources.

Keep questions coming.