FAQ: Pre-Exposure Prophylaxis (PrEP) for HIV

Medically Reviewed by Jonathan E. Kaplan, MD on March 06, 2024
Written by Elizabeth M. Ward, RD, MS
4 min read

Because there's currently no cure for HIV, it's better to prevent an infection if you can than to take medicine for the rest of your life.

For years, the most common prevention method has been condoms. Newer methods, like PrEP, are showing real promise, helping to lower the chance of infection for people who are HIV-negative. And both men and women can use it.

PrEP stands for pre-exposure prophylaxis. It's a pill or injection you can take when you don't have HIV but are at high risk to get the virus, perhaps because of sex or injection-drug use. It helps before you're infected, so HIV can't settle into your body and spread.

PrEP medications to prevent HIV include:

The pill forms of PrEP should be taken once a day, every day to prevent HIV from taking hold in your body. The injectable Apretude is taken once every eight weeks 

Skipping a dose or not taking PrEP regularly lowers the medications' ability to protect you. If you take the oral medication:

  • Every day, your level of protection is around 99%
  • 4 days a week, your level of protection is around 96%
  • 2 days a week, your level of protection is around 76%

It can take 7-20 days from when you take your first pill until it's most effective.

Given every two months, Apretude has been shown to be 90% effective in lowering the risk of HIV  

The first PrEP medication, Truvada, was approved by the FDA in 2012 and Descovy was approved in 2019. They may cause nausea, stomach upset, and dizziness, but these typically go away over time. There may also be issues with pain or swelling at the injection site.

None of the side effects have been life-threatening. Even after taking PrEP for 5 years, people aren't having health problems because of it. Apretude was approved in late 2021. Side effects of it include fatigue and headaches. 

And you can't get HIV from taking PrEP, because it's not a vaccine. There's no HIV in it.

PrEP doesn't seem to cause problems when you take it while you're using hormonal birth control, medication for depression, or alcohol and other party drugs.

If you have kidney or bone problems, though, let your doctor know before you start taking PrEP medication.

We're still learning if PrEP later affects kids whose mothers used it during pregnancy and breastfeeding.

It's a good option for someone in any of these situations:

  • In an ongoing relationship with an HIV-positive partner
  • Has sex with multiple partners and doesn't always use condoms
  • Injects drugs or shares needles

If you're a woman who wants to have a baby with an HIV-positive man, ask your doctor about PrEP. It may be a way to lower the chances of you and your baby getting HIV.

Research is still being done on the effects of taking PrEP when you're transgender and having hormone therapy. No bad reactions have been reported so far.

For PrEP to protect you, it needs to be taken before you come in contact with the virus. PrEP isn't a cure for HIV.

If you think you've been exposed, call your doctor right away or head to the emergency room. If you start taking a different kind of medication called PEP (post-exposure prophylaxis) within 72 hours, it can lower your odds of HIV infection.

PrEP can stop you from getting HIV, but it doesn't protect you from other sexually transmitted diseases like syphilis, chlamydia, and gonorrhea, so you'll still need condoms for that. PrEP also doesn't prevent pregnancy.

You should visit your doctor every 3 months for an HIV test and follow-up care while you're taking PrEP.

It isn't a pill you have to take forever. You get to decide when to start and stop PrEP. Just remember that if you don't take it regularly, you aren't as safe.

Once you've started taking PrEP, you should stay on it for at least a month after you were last exposed to HIV.

If you think that you're no longer at risk of getting HIV, talk with your doctor before you stop taking PrEP.

You need a prescription for it, from any health provider -- doctor, nurse practitioner, or physician assistant -- who is qualified. You might need to contact your local health department or a local AIDS organization to find someone who understands what it is and is comfortable writing the prescription for you.

You'll also need to get an HIV test first to make sure you don't already have the virus.

PrEP is expensive -- it can cost as much as $13,000 a year without insurance. Most insurance plans do cover Truvada, which means you'd pay your normal copay amount for brand-name drugs.

Coverage differs from state to state, but PrEP should also be covered by Medicaid and Medicare.

If you have to pay for PrEP yourself, there are financial assistance programs that may help, including from the drug manufacturer, public health services, and clinical trials.