Lamivudine

Key facts

• Lamivudine (in Epivir, and combined with other antivirals in Triumeq and Combivir) blocks HIV and hepatitis B from copying their genetic material.
• It is taken once or twice daily, every day at the same times, alongside other antiviral drugs, to keep the virus suppressed.
• If you have hepatitis B, do not stop lamivudine without medical supervision. Stopping suddenly can cause a severe liver flare, even after months of the drug working well.
• Seek urgent care for yellowing of the skin or eyes, dark urine, or severe abdominal pain.

What lamivudine treats

Lamivudine treats HIV-1 infection, always as part of a combination regimen, and chronic hepatitis B infection, where it lowers the amount of virus in the blood and reduces liver inflammation. It is also used late in pregnancy to lower the chance of a mother with hepatitis B or HIV passing the infection to her baby.

How lamivudine works

Lamivudine mimics a natural building block the virus needs to copy its genetic material. The viral enzyme mistakenly incorporates it into the new viral strand, which stops that strand from growing and halts replication.

Before you take it

• Avoid lamivudine if you have a known allergy to it or related antivirals.
• Tell your prescriber about kidney problems, since the dose depends on how well your kidneys filter the drug.
• If you have HIV, lamivudine must always be combined with other antiretrovirals. Using it alone lets the virus develop resistance quickly.
• If you have both HIV and hepatitis B, your regimen needs to treat both viruses adequately.

Side effects

Common effects include headache, nausea, fatigue, diarrhea, and a mild rash that usually settles on its own.

Stop and seek urgent medical care for any of these:

• Swelling, hives, or difficulty breathing, signs of a severe allergic reaction.
• Yellowing of the skin or eyes, dark urine, or a swollen, tender liver.
• Rapid breathing, unusual muscle pain, or vomiting, rare signs of lactic acid buildup linked to this drug class.

Safety essentials

• Never stop lamivudine abruptly if you have hepatitis B. Flares can be severe, and your liver needs close monitoring for months after stopping.
• Lactic acidosis and severe liver enlargement with fatty change are rare but serious risks shared by this drug class; report unusual muscle pain or breathlessness promptly.
• Lamivudine must always be part of a combination regimen for HIV, never used alone.
• Kidney function should be checked periodically, since it determines your correct dose.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.