PrEP prevents HIV
- PrEP is safe and can reduce your risk of HIV by more than 99%.
- Doxy-PEP and condoms help prevent other STIs.
- Vaccines protect you from mpox, hepatitis A and B, HPV (warts), and meningitis.
Two pill types available
- Taking PrEP as a daily pill, you have 2 options: Truvada or Descovy.
- Your provider will recommend one based on your medical history and what coverage you qualify for.
When daily PrEP protects
- Taking PrEP as a daily pill protects you from HIV when having any type of sex.
- If you use Truvada, you are also protected from HIV when injecting drugs. Descovy has not been studied for protection when injecting drugs.
Daily PrEP works for all genders
- Taking 1 pill of PrEP every day works for all genders. It protects you against HIV no matter what body parts you use for sex.
- You can take PrEP even if you drink alcohol, use drugs, take hormones, or use birth control.
How to take PrEP as a daily pill
1 pill per day
- Take 1 pill every day. This provides the best protection.
When protection starts
- When starting PrEP, it takes time for the medication to build up in your body. Protection starts at different times based on the type of protection you need:
- Sex using your penis or anus: up to 1 week (if using Truvada and you take 2 pills at once on day 1, protection will begin 2 hours later)
- Sex using your vagina/front-hole: up to 1 week
- When injecting drugs: up to 1 week
How to remember to take the pill
Here are some ways to help yourself remember:
- Try to take the pill at the same time each day.
- Set pill-taking reminders in your phone.
- Consider taking a pill with you if you will be out.
Missed a dose?
- Just take it when you remember. If it’s already time for your next dose, just take that next dose.
- If you have questions about restarting PrEP pills after a gap, call your provider.
Possible side effects
- Some people have gas, nausea, or headache. These symptoms go away within the first month for most people.
- Some PrEP medications can cause small changes in kidney function and bone mineral density, or small changes in lipids (i.e. cholesterol).
Maintaining your pill supply
- Refills are not always automatic. Contact your pharmacy when you have 5 pills left so you do not run out.
- Before traveling, let your healthcare provider and pharmacy know that you may need an extra refill.
Cost
- PrEP as a pill is free for most people.
- If you do have costs for PrEP medication, assistance programs may help cover those.
- For help, contact the City Clinic PrEP line at 628-217-6692.
Lab testing
- Before starting PrEP, you will get tests for HIV, STIs, kidney function, and Hepatitis B and C.
- While taking PrEP, you will get tested for HIV and STIs regularly. You will also get testing for kidney function and/or lipids routinely, depending on which pill you are taking.
Switching or stopping PrEP
Switching your type of PrEP or stopping PrEP
- If you want to stop taking daily PrEP, talk to a healthcare provider about other HIV prevention options. You can switch to taking PrEP pills on the 2-1-1 schedule or take PrEP as a shot, or you can use condoms.
- If stopping PrEP altogether, take at least enough daily doses after the last time you have sex to protect from HIV:
- Sex using your penis or anus: 2 daily doses
- Sex using your vagina/front-hole: 7 daily doses
If you have sex without a condom while not taking PrEP
- Call your provider within 72 hours for PEP.
- Get an HIV test as soon as you can when restarting PrEP. This helps you be sure of your HIV status after being off PrEP. PrEP is only recommended for people who are HIV negative.
This information is provided by San Francisco City Clinic. Visit our homepage at sf.gov/cityclinic.
Information on this page last revised February 19, 2026