Both types of questions have one commonality—the people asking the question desperately need information that can help them figure out how to move on with their lives in a safe and healthy way.

This quick reference can help. The following are answers to and discussion of the most common questions healthcare professionals get from people who are worried about the realities of having an STI.

The simplest answer to this question is that you can’t know if you got an STI from an episode of unprotected sex until you get tested. That’s because many, if not most, STI infections are asymptomatic. In other words, they don’t cause any symptoms.

However, what you probably actually want to know is how long you have to wait until STI symptoms show up if you’re going to see them. The answer varies from disease to disease. It could be anywhere from a few days to a few years.

To make matters even more confusing, there’s also a window period between when you are infected and when you can first test positive for it. That varies with every STI and may extend to six months or more.

Some of them may be lying. However, there are a lot of people who really have no clue they are infected with one of the herpes viruses (herpes simplex virus 1, or HSV-1, and herpes simplex virus 2, or HSV-2). That’s because infections often have no symptoms.

In addition, healthcare providers do not regularly perform blood tests for herpes unless someone has a known exposure.

There is a common misconception that if you sleep with someone with an STI, you will automatically get that STI the first time. That isn’t true.

Still, people often use that reasoning to continue not using condoms or other forms of barrier protection after they’ve slipped up. “After all,” they rationalize, “if I was really at risk from this person, then I’m already in trouble.” Fortunately, however, that isn’t true.

It’s certainly best to practice safer sex every single time you have sex. However, messing up once doesn’t mean that you can’t go back to being safe.

It’s always worth using a condom the next time you have sex even if you didn’t this time. Just because someone has an STI, it doesn’t mean their partners will automatically get it.

Penile discharge can be a symptom of any of a number of common STIs. The only way to tell which one you have—or if you have an STI at all—is to go visit your local healthcare provider or a free clinic and get tested.

There is no way for someone to self-diagnose what STI is causing a discharge without having a laboratory test done. Usually, testing is simply giving a urine or blood sample. You probably won’t need to undergo a urethral swab.

Acknowledged STI infections aren’t necessarily relationship deal breakers for people. That’s true even with lifelong infections such as human immunodeficiency virus (HIV) and herpes. On the other hand, lying about an STI almost always will cause a problem. 

You don’t need to bring up these topics on the first date. Just don’t put the conversations off until the night you plan to first have sex. Having to deal with a heavy discussion in the heat of the moment is a bad idea. It may make it more likely your partner will make a decision they’ll regret.

A lot of people don’t really think of oral sex as sex. However, it can pose a significant STI risk. That’s why, unless you have both been comprehensively tested, it’s a good idea to use condoms or dental dams whenever you have oral sex.

There is not yet a commercial HPV test for people with male genitalia (the usual HPV tests are done on cervical cells), but that doesn’t mean HPV exposure and outcomes are not important. It’s just that it’s hard to figure out how to implement population-wide testing in a useful way.

So the only way you’d know for certain if you have an STI would be if you’d asked your healthcare provider to test you and have received the results. Even then, your certainty would only last as long as you continued to avoid potentially risky behavior.

When someone who is in a long-term relationship that the partners agreed would be exclusive is diagnosed with an STI, it can be heartbreaking. The first instinct is almost always to assume that their partner has cheated on them. While in many cases that may be true, it isn’t always.

If you both weren’t tested before starting the relationship, or if you are early in the relationship, it’s possible that your partner might have had an asymptomatic infection since before you got together. They also might have only infected you recently even if you’ve been involved for years.

This specific question blends several misconceptions, including: 

That the main STI risk of oral sex is HIVThat all sex workers have HIVThat STIs are transmitted every time you have sex

None of those statements is true.

It’s a good idea to use protection whenever you engage in any type of commercial sex (or casual sex). Not doing so potentially puts you at substantial risk. Besides, if you have the means to purchase oral sex, then you should have the means to take precautions in advance.