Efavirenz: What It Is, How It Works, and What You Need to Know

When it comes to fighting HIV, Efavirenz, a non-nucleoside reverse transcriptase inhibitor (NNRTI) used to block HIV from multiplying in the body. Also known as Sustiva, it's been a backbone of HIV treatment for over two decades. It doesn’t cure HIV, but when taken as part of a combo regimen, it keeps the virus so low that it can’t damage the immune system or spread to others. People living with HIV who take Efavirenz regularly often see their viral load drop to undetectable levels within weeks — a game-changer for long-term health.

Efavirenz works by targeting a specific enzyme HIV needs to copy itself. Without that enzyme, the virus can’t make new copies. It’s usually paired with other drugs like tenofovir and emtricitabine — a combo known as Atripla. This isn’t just about taking one pill; it’s about building a system that stops the virus in its tracks. But it’s not without trade-offs. Many users report vivid dreams, dizziness, or trouble sleeping, especially in the first few weeks. For some, these side effects fade. For others, doctors switch them to newer drugs like doravirine or rilpivirine, which work just as well but with fewer brain-related side effects.

It’s important to know Efavirenz isn’t for everyone. People with a history of depression, seizures, or liver problems need careful monitoring. It can also interact with other meds — like some antibiotics, antifungals, or even herbal supplements like St. John’s wort — which can make it less effective or more toxic. That’s why sticking to your prescribed combo and talking to your provider about every other drug or supplement you take matters more than you might think.

Even though newer HIV drugs have fewer side effects, Efavirenz is still widely used around the world because it’s cheap, stable at room temperature, and works reliably. In places where healthcare access is limited, it remains a lifeline. But in wealthier countries, many clinics now start patients on gentler options — unless Efavirenz is the only choice that fits their needs.

Below, you’ll find real patient-focused guides that dig into how Efavirenz fits into the bigger picture of HIV care. You’ll see how it compares to alternatives, what to expect when you start it, how to handle side effects, and what to watch for when combining it with other meds. These aren’t clinical brochures — they’re practical, no-fluff insights from people who’ve lived through it.