References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Lamivudine (also known as 3TC, brand name Epivir) is one of the most widely used nucleoside reverse transcriptase inhibitors (NRTIs) in HIV treatment. It forms the backbone of many combination regimens and is found in several single-tablet treatments including Dovato, Triumeq and Combivir. It’s well tolerated, has few side effects, and has decades of clinical evidence behind it.
Here’s what lamivudine does and what to expect if it’s part of your treatment.
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How Lamivudine Works
HIV replicates by converting its RNA into DNA using an enzyme called reverse transcriptase. Lamivudine mimics one of the building blocks of DNA. When reverse transcriptase incorporates lamivudine instead of the real building block, the DNA chain is terminated and the virus can’t complete its copy.
Where You’ll Find Lamivudine
| Combination | Other Ingredients |
|---|---|
| Dovato | Dolutegravir |
| Triumeq | Dolutegravir + abacavir |
| Kivexa | Abacavir |
| Combivir | Zidovudine |
| Epivir (standalone) | None — used with other drugs |
Side Effects
Lamivudine is one of the best-tolerated HIV drugs available. Side effects are uncommon and usually mild:
- Headache
- Nausea (usually settles quickly)
- Fatigue
- Insomnia (rare)
Serious side effects are very rare. Lactic acidosis (a build-up of lactic acid) is a theoretical risk with all NRTIs but is exceptionally uncommon with lamivudine.
Hepatitis B Caution
Lamivudine also has activity against hepatitis B. If you have hepatitis B co-infection, stopping lamivudine can cause a hepatitis B flare — a sudden worsening of liver inflammation. Never stop lamivudine without discussing this with your HIV team if you have or may have hepatitis B.
Drug Resistance
The main resistance mutation to lamivudine (M184V) develops relatively easily if the virus is allowed to replicate while on the drug. However, this mutation actually makes HIV weaker and more sensitive to other drugs. In modern combination therapy, this is rarely a practical problem.
Read more: Dovato | Abacavir and lamivudine | What is HIV?
Frequently Asked Questions
Is lamivudine still used in HIV treatment?
Yes — it’s one of the most commonly used NRTIs globally and is a key ingredient in several first-line regimens including Dovato and Triumeq.
Can I take lamivudine if I have hepatitis B?
Yes, but with caution. Lamivudine treats both HIV and hepatitis B. If you stop it, hepatitis B can flare. Your HIV team will manage both conditions together.
Does lamivudine cause weight gain?
Lamivudine itself is not strongly associated with weight gain. Any weight changes on combination therapy are more likely related to other drugs in the regimen.
Related reading
- Choosing the Right PrEP Drug: Truvada vs Descovy
- Dovato for HIV: A Two-Drug Regimen
- Triumeq for HIV: A Straightforward Guide
- Efavirenz for HIV: An Older NNRTI Still in Use
- Eviplera: How This Anti-HIV Drug Works
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
