Everything You Need to Know About PrEP

All you need to know about PrEP- who should take it, how often, and what to expect.

There is a lot that people don’t know about PrEP. For those in the generation once removed from the AIDS crisis that ravaged the LGBTQ+ community in the late 80s early 90s, HIV holds a different weight. There is a lot of misinformation about HIV and as a result, people exactly don’t know what PrEP is, how it works, or what to expect. At FOLX, we’ve compiled a list of things that you should know about PrEP and our process of prescribing it.


  • The biggest takeaway is to remember that PrEP lowers chances on getting HIV from sex by up to 99% or from sharing injection equipment such as needles (IV drugs) by up to 74%. This means that if taken daily, PrEP just about eliminates the chance of getting HIV from having the types of sex you want to have.

  • PrEP does not protect against other STIs (sexually transmitted infections), so being mindful about the types of protection and conversations you have with your sexual partners is still important. Consistent and correct use of condoms is considered 90-99% effective while inconsistent and incorrect use is 60-70% effective, but condoms do limit exposure to other STI infections that PrEP does not.

  • PrEP takes 21 days through vaginal tissue and 7 days through anal tissue to become fully effective, If you are a trans women or trans feminine person who has had bottom surgery and has a neovagina, we recommend erring on the side of 21 days for adequate protection.

  • PrEP loses its efficacy when taken less than 5 days a week, so take it everyday. With food or an over the counter anti-nausea aid.

  • If your partner or partners are on PrEP (and remain HIV negative) you will too, whether you're on PrEP or not.

  • In recent years, it’s been firmly established by a large body of clinical evidence that if someone with HIV has an undetectable viral load for at least 6 months, then they cannot sexually transmit the virus to others. This is often referred to as U=U, or “Undetectable = Untransmittable.” You do not have to take PrEP if your partner’s test stays undetectable, but we will still prescribe PrEP if you think taking it is the right decision for you.

Side Effects

  • Common side effects of PrEP include headache, loss of appetite, and rash.

  • Like many new medications, PrEP may initially cause fatigue but this should go away within a month.

  • It’s important to know that PrEP does not decrease muscle mass or weight.

  • While there are few studies on this, PrEP does not decrease the effectiveness of hormone replacement therapy (HRT) and HRT does not affect how well PrEP works.

  • There are a few longer term risks of taking PrEP that need to be monitored to make sure that people are staying healthy while on it. These risks have to do with the kidneys, liver and bone density. It's important to monitor how well your kidneys are working while taking PrEP, which is why we need regular creatinine labs. This is even more important for people who have risk factors for kidney disease, such as uncontrolled high blood pressure or untreated diabetes. While lactic acidosis and liver disease is listed as a risk on the medication label, there is no data that suggests FTC/TDF for PrEP causes either of these problems. Lastly, PrEP can decrease bone density; however, this bone loss goes back to normal after 12-18 months of stopping PrEP.

  • When combined with other medications such as pain medications such as ibuprofen and antiviral medications such as acyclovir and famciclovir, PrEP can increase the risk for kidney damage. While this is less common, please let us know what other medications you take so we can provide you with more personalized information.

And the rest of the fine print

  • PrEP, like all medication, expires.

  • We prescribe generic Truvada at FOLX. Gilead Sciences used to own the patent for PrEP but this expired last year, allowing more companies to offer PrEP via the Generic Truvada. Descovy is a different version of PrEP with slightly different side effects. We do not currently offer Descovy.

  • Generic Truvada is safe for people who are pregnant, might be pregnant or are chestfeeding.

  • And finally, HIV treatment and prevention are different. ART is what you take when you have been diagnosed with HIV, which is different from PrEP which is a preventive measure to stop the transmission of HIV. While ART can’t cure HIV, it can help people who are HIV+ to live long and healthy lives.