Efavirenz: Quick Guide to Uses, Dosage, and Safety

If your doctor prescribed Efavirenz, you probably have questions about how to take it and what to expect. This guide breaks down the basics so you can use the medicine correctly and feel more confident about your treatment.

How Efavirenz Works

Efavirenz belongs to a class of drugs called non‑nucleoside reverse transcriptase inhibitors (NNRTIs). It blocks an enzyme the HIV virus needs to copy its genetic material. By stopping that step, the drug slows the virus down and helps your immune system recover.

The medicine is never used alone. It’s combined with other antiretrovirals in a regimen called ART (antiretroviral therapy). Together, the drugs keep the virus at low levels and reduce the chance of resistance.

Dosage, Side Effects, and Safety

The standard adult dose is one 600 mg tablet taken once a day, usually at night. Taking it with food can reduce stomach upset and help your body absorb it better. Nighttime dosing also lessens the chance of vivid dreams, a common side effect.

If you miss a dose, take it as soon as you remember—unless it’s almost time for your next dose. In that case, skip the missed one and continue your regular schedule. Don’t double up; extra doses won’t boost effectiveness and may increase side effects.

Most people experience mild side effects like dizziness, headache, or trouble sleeping. Efavirenz is known for causing vivid or scary dreams, especially during the first few weeks. If the dreams become too intense, talk to your doctor; they may adjust the timing or suggest a short break.

Serious side effects are rarer but can include severe rash, liver problems, or mood changes such as anxiety or depression. If you notice a rash that spreads, yellowing of the skin, or sudden mood swings, get medical help right away.

Efavirenz interacts with several other drugs. Rifampin (used for tuberculosis), certain antifungals, and St. John’s wort can lower its levels, making the HIV treatment less effective. Always let your pharmacist know every medication, supplement, or herbal product you’re taking.

Because the liver processes Efavirenz, doctors often check liver enzymes before starting and during treatment. If you have pre‑existing liver disease, your provider may choose a different regimen.

Pregnant women need special attention. Efavirenz can affect the developing baby, especially in the first trimester. If you become pregnant while on Efavirenz, inform your doctor immediately; they may switch you to a safer option.

Regular monitoring is a key part of staying safe. Blood tests will track your viral load and CD4 count, while liver function tests watch for any organ stress. Most clinics schedule these checks every few months, at least during the first year of therapy.

In short, Efavirenz is a powerful tool against HIV when taken as directed. Keep a consistent schedule, watch for side effects, and stay in touch with your healthcare team. Doing so maximizes the benefits and keeps you on track toward a healthier life.