Emtricitabine

Key facts

• Emtricitabine is a nucleoside reverse-transcriptase inhibitor (NRTI). It is always used as part of a combination regimen, never alone, most often paired with tenofovir.
• It is taken once daily, usually as a fixed-dose combination tablet (such as Truvada), for either HIV treatment or HIV pre-exposure prophylaxis (PrEP).
• If you also have hepatitis B, stopping emtricitabine can trigger a severe, sometimes life-threatening flare of hepatitis; your liver needs monitoring for several months after you stop.
• Before starting PrEP, you must have a confirmed negative HIV test; taking it during undiagnosed HIV infection can allow drug-resistant virus to develop.

What emtricitabine treats

Emtricitabine treats HIV-1 infection, always combined with other antiretroviral drugs, to reduce the amount of virus in the blood and protect the immune system. Combined with tenofovir, it is also used as daily pre-exposure prophylaxis (PrEP) to reduce the risk of acquiring HIV in people who are HIV-negative but at ongoing risk of exposure.

How emtricitabine works

HIV needs an enzyme called reverse transcriptase to convert its genetic material into a form it can insert into human cells. Emtricitabine resembles one of the natural building blocks the virus uses for this step. Once incorporated, it stops the growing DNA chain from extending, which halts the virus copying itself. Because resistance develops quickly to any single antiretroviral drug, it is always combined with at least one other agent.

Before you take it

• You need a hepatitis B test before starting: if you have chronic hepatitis B, your prescriber will plan how to monitor and manage your liver if treatment is ever stopped.
• For PrEP, a confirmed negative HIV test is required before the first dose and at regular intervals during treatment.
• Tell your prescriber about kidney problems, since the dose is adjusted for reduced kidney function.
• Emtricitabine does not cure HIV and does not prevent transmission of other sexually transmitted infections.

Side effects

Common effects include headache, nausea, diarrhoea, fatigue, and a mild skin rash.

Seek urgent medical care for:

• Yellowing of the skin or eyes, dark urine, or severe abdominal pain.
• Unusual muscle pain, weakness, or difficulty breathing (possible lactic acidosis).
• Signs of a severe allergic reaction: facial swelling, hives, difficulty breathing.
• Worsening hepatitis symptoms after stopping the drug.

Safety essentials

• Never stop emtricitabine abruptly if you have hepatitis B without medical supervision; a severe hepatitis flare can occur, and your liver must be monitored closely for several months afterward.
• Confirm your HIV status before starting or continuing PrEP, and keep to the testing schedule your prescriber sets.
• Take it exactly as prescribed and do not skip doses; inconsistent dosing lets the virus develop resistance to the whole regimen.

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