Truvada, taken as directed, gives nearly perfect protection from HIV, but it does not protect you from other STIs like syphilis, gonorrhea, and chlamydia.

The PrEP regimen also includes a quarterly checkup with a healthcare provider that includes testing for HIV and other STIs. Some people also use condoms to reduce the risk of contracting other STIs during sex. Some people rely on quarterly visits to their doctor to identify and treat any STIs that they might get.

Note that condoms are typically always used to prevent STIs that can pass between the penis and the anus or the vagina / when fucking. Few people use condoms for oral sex. Few people use a barrier for oral-anal or oral-vaginal sex. STIs can be transmitted these ways.

Some people have decided the pleasure outweighs the risks of contracting an STI from these events. Other people don’t know/forget that STIs can be transmitted these ways. Still other people will use some kind of barrier in these cases, not wanting to chance it.

STIs aren’t everywhere, looking to “get you” if you don’t use protection. That also doesn’t mean there’s no possibility of getting an STI from sex without a barrier. It helps to have a more realistic understanding of how common STIs are. This site, Your Honest-to-God Guide to STDs, does a good job of explaining STI risks in plain language.

But doesn't simple logic tell us that HIV negative men on Truvada would have higher STI rates? No. it doesn't. Although it's hard to compare a quantifiable group of PrEP consumers with non PrEP-users at equal risk, two major studies have done exactly that:

• The PROUD study in the UK looked at a group of 545 HIV negative men who were considered to be at high risk for HIV because of regular anal sex without condoms. Half were given Truvada, half were given nothing. According to the researchers, there was no change in the incidence of sexually transmitted infections (STIs) when men started PrEP.
• Dr. Albert Liu's demonstration project in San Francisco, Miami, and Washington looked at 557 PrEP consumers over 48 weeks. STI rates were high before they began using Truvada. They did not increase over the next year (nor decrease).

Even in light of that, people have different comfort levels around this issue. Since STIs are a complicated topic and there is no agreement in this group on what the “Best” thing to do, the only answer we can give is you have to decide for yourself what is right for you.

Regarding condoms and other STIs, Dr. Robert Grant, Principal Investigator for the iPrEX study that proved PrEP works, summed up the issue this way:

"Please don't tell anyone that they have to use condoms. That, by its very nature, is a violent indication; you're imposing your will on them. You're also discrediting yourself because as soon as they go out and have sex without a condom, they've proved you wrong; they didn't have to use condoms. You told them that they had to, and they didn't, and obviously they don't have to. So you don't want to set yourself up as someone who communicates in a violent way; you don't want to set yourself up as someone to be proven wrong the first time someone has sex without a condom so 'you must use condoms' is not the right way to frame this." — Dr. Robert Grant, 6 October 2015,

You can listen to the whole recording. This excerpt begins just before the 41-minute mark.