9 Things to Know About Emtricitabine/Tenofovir Disoproxil Fumarate (Truvada)

Written by Kendall K. Morgan
Medically Reviewed by Jonathan E. Kaplan, MD on April 21, 2025
5 min read

Emtricitabine/tenofovir disoproxil fumarate (Truvada) is used in two ways. Doctors can prescribe it together with other HIV medicines to treat an HIV infection. They can also prescribe it to people who are at risk of getting an HIV infection to reduce their chances of catching the virus.  (That’s known as preexposure prophylaxis, or PrEP.)

When you fill your first prescription for emtricitabine/tenofovir disoproxil fumarate (Truvada), you should get a medication guide. It’s a good idea to read through this information. Each time you get a refill, read through it again. Ask your doctor any questions you have. 

If you’re thinking about taking the drug, or are new to taking it, there are a few things you should know.

Before you take it to treat an HIV infection, your doctor will test you for a hepatitis B virus (HBV) infection. If you have both HIV and HBV, you can still take it. But your hepatitis B infection could get a lot worse if you ever stop taking the medication.

If you have HIV and HBV:

  • Don’t let yourself run out of your medicine.
  • Don’t stop taking it without talking to your doctor.

If you decide with your doctor to stop taking the medication, your doctor needs to watch you closely. You’ll need blood tests often to check your HBV infection. You may also need to take another medicine to treat the HBV. 

To take the medication by itself for PrEP, you can’t already have an HIV infection. You’ll need to get tested to make sure you don’t. Never take emtricitabine and tenofovir disoproxil fumarate for HIV prevention until you’re sure you’ve tested negative.

Even if you test negative for HIV, you could still have it. That’s because HIV tests can miss an infection in its early stages. 

If you’re thinking about using this medication for PrEP and have had recent flu-like symptoms, tell your doctor. Also, let your doctor know if you start having any symptoms when you’re taking the drug. 

A new HIV infection may cause symptoms like:

  • Tiredness
  • Fever
  • Achy muscles or joints
  • Headache
  • Sore throat
  • Vomiting
  • Diarrhea
  • Rash
  • Night sweats
  • Swollen lymph nodes in your neck or groin

Taking emtricitabine and tenofovir disoproxil fumarate doesn’t guarantee you won’t get an HIV infection. So you need to take steps to lower your risk of HIV and other sexually transmitted infections (STIs) while you take it. These include:

  • Knowing whether your sex partners have HIV
  • Knowing whether sex partners with HIV take antiviral medicines and whether their HIV is at detectable levels
  • Getting tested for HIV regularly as your doctor advises
  • Getting tested for other STIs that could make it easier for you to get HIV
  • Telling your doctor if you were exposed to HIV
  • Using condoms and taking other steps to lower your odds of exposure
  • Taking your emtricitabine and tenofovir disoproxil fumarate exactly as your doctor prescribes

If you take the medication for PrEP and get an HIV infection, your doctor will need to prescribe additional medicines. Taking emtricitabine and tenofovir disoproxil fumarate alone could make your HIV harder to treat later.

Before you take this drug to treat or prevent HIV, you need testing to see:

  • Whether you have an HIV infection or hepatitis B infection
  • How your kidneys are working
  • Whether there’s too much blood sugar in your pee
  • Whether there’s too much protein in your pee

If you have other health problems, you may need extra testing.

While you take the medication for PrEP, you need HIV testing at least every 3 months. You also need testing to see if you get another type of STI. And you should get tested if you’ve been exposed to HIV in the last month or have possible symptoms of an HIV infection.

Always follow your doctor’s instructions. You take this medicine as a pill once a day. You can take it with or without food. If you’re taking it for an HIV infection, take it along with your other HIV medicines. Your doctor may recommend that you also take a calcium and vitamin D supplement to help protect your bones.

Never skip a dose, change how much you take, or stop taking it unless your doctor tells you to. To avoid missing a dose, make sure you don’t run out of medicine. If you forget a pill, take it as soon as you remember that day. But don’t take more than one dose per day.

If you accidentally take more than you should, call your doctor or go to the emergency room.

Keep your medicine at normal room temperature in the container it came in. Close the bottle tightly after you take your medicine. Make sure kids can’t reach or open the container. 

There’s no evidence that this medication increases the risk of major birth defects. But the research is limited. It’s also not clear if the drug makes you more likely to miscarry.

If you’re at risk for HIV and find out you’re pregnant, talk to your doctor about whether you should start or keep taking emtricitabine and tenofovir disoproxil fumarate.

If you take this medication while breastfeeding, some of it can end up in your breastmilk. Doctors don’t have enough information about whether this might cause you to make more or less milk. It’s not known, either, if it can affect a nursing baby.

If you take this medication for PrEP, talk to your doctor about whether you should keep taking it while you breastfeed. 

If you’re breastfeeding and have an HIV infection, talk to your doctor about options for feeding your body.

This combination drug hasn’t been tested in children for safety and effectiveness. The dosage for kids and teens is based on clinical trials that separately tested each of the two medicines it contains. 

Children shouldn’t take this medicine to treat HIV unless they weigh at least 37.5 pounds (17 kilograms). Young people at high risk of HIV can start taking the medication to prevent HIV infection once they weigh at least 77 pounds (35 kilograms). There’s no evidence to show the drug is safe for those who weigh less than that.

Clinical trials of this medication didn’t include many people 65 or older. So doctors aren’t sure whether people in that age group respond to the drug in the same ways that younger people do.