Yes, if the affair was sexual. Get tested, even if you have no symptoms, and talk to a clinician promptly. Some infections have no symptoms at all, and a test is a practical health step, not a verdict on your relationship. If sex with your partner happened in the last three days and you are worried about HIV exposure, ask a clinician about PEP today, because that option is time sensitive.
This article is not medical advice, and it cannot tell you whether you have an infection. Only your own clinician can do that, based on what happened and when.
The one timing that cannot wait
PEP is medicine taken after a possible HIV exposure to lower the chance that HIV takes hold. The CDC guidance on PEP says it must be started within 72 hours of a possible exposure, and the sooner the better, with every hour counting. If you are prescribed PEP, you take it daily for 28 days.
That 72 hour window is counted from the possible exposure, not from the day you found out about the affair. If your partner had sex with you in the last three days, and you now know they were also having sex with someone else, call your clinician, an urgent care clinic, or an emergency department now and say you think you may have been exposed to HIV and want to ask about PEP. Do not wait to finish reading, or to have a long conversation first.
Don-David Lusterman, in Infidelity: A Survival Guide, describes discovery as a blow that needs a step by step response, not a single decision made in shock. Testing is one of those steps. It is small, concrete, and it belongs to you.
What "get tested" actually means
There is no single test called a full STI panel that means the same thing for everyone. What you need depends on your age, your sexual history, what kind of sex you had, whether you have symptoms, and whether you are pregnant. That is the point the CDC makes in its testing guidance: a clinician can help you decide which tests are right for you.
In practice, a clinician will usually talk with you about testing for chlamydia, gonorrhea, syphilis, and HIV, and about hepatitis B and hepatitis C where relevant. The CDC guidance notes that everyone ages 13 to 64 should be tested at least once for HIV. Mayo Clinic gives the same broad message: everyone at risk needs testing, because many of these infections cause serious health problems and often have no symptoms.
Some tests use blood, some use urine, and some use a swab, depending on the kind of sex you had. Herpes testing is different: Mayo Clinic notes that clinicians usually suggest testing for genital herpes only if you have symptoms or other risk factors. You do not need to work all of this out before you call. Naming the situation is enough.
Caroline Madden, in Blindsided by His Betrayal, writes about the shock that follows discovery, when the body and the mind are both reeling. A test can feel like one more shock. It helps to name it for what it is: a health check after a risk you did not choose, not a test of your worth.
Why no symptoms does not mean no infection
You feel fine, so you assume you are fine. Or your partner says they feel fine, so you assume they are fine. Neither assumption is safe. The CDC is direct about this: STIs often have no symptoms, so you may not know you have one, and even without symptoms, infections can cause serious health problems and spread to others.
That is why "I have no symptoms" is not a reason to skip testing, and why "my partner has no symptoms" is not a reason to trust that you are safe. It is also why a negative test does not mean the betrayal did not matter. A test result answers a health question. It does not answer whether trust can be rebuilt, or whether the relationship should continue.
Kevin Skinner, in Treating Trauma from Sexual Betrayal, describes sexual betrayal as an injury that can bring trauma responses like those of post-traumatic stress, including intrusive memories and flashbacks. Getting tested does not settle the trauma, but it does settle one concrete question, and that matters when your mind is already working overtime.
When to test, and why one test is rarely the whole story
Book the first test now. Do not wait until you feel calmer, or until you and your partner have agreed on a story about what happened. The first appointment is a baseline: it finds infections that are already detectable, and it gives your clinician the information to plan what comes next.
Then ask your clinician a direct question: "When should I come back for a repeat test?" Your clinician will base the repeat timing on what happened and when, and the CDC notes that some people may need repeat testing. Write down the date they give you before you leave the clinic. Scott Haltzman, in The Secrets of Surviving Infidelity, writes about taking practical steps in the first stage after discovery, and booking a test is one of them.
Tell your clinician the truth about timing, even if it is painful to say out loud. "We had sex last Tuesday" is medical information, not a confession. If you have symptoms, such as burning, discharge, sores, a rash, or pain, do not wait for a planned appointment. If you are pregnant, say so at the start, because pregnancy changes which tests are done and when.
What to say to a clinician
Many people put off testing because they do not know how to start the conversation. You do not need a long explanation, and you do not need to tell the whole story of the affair. A clinician has heard this before, and their job is to test and treat, not to judge your relationship.
Try one of these, in your own words: "My relationship status has recently changed, and I would like a full STI panel." Or: "I recently found out my partner had a sexual affair. We had sex as recently as [day], and I would like to be tested, including for HIV, syphilis, chlamydia, and gonorrhea. Can you tell me what you recommend and when I should come back for a repeat test?"
If you are worried about cost, privacy, or being seen at your usual clinic, say so. The CDC notes that there are clinics that provide confidential and free or low cost testing. At home test kits also exist for some infections. If you use a home test, tell your clinician, and confirm a positive result with them. A negative home test when you have symptoms, or when you know you were exposed, is also a reason to contact a clinician for more testing, as Mayo Clinic advises.
Debi Silber, in Trust Again, writes about how betrayal can shake trust in yourself as well as trust in your partner. Asking for a test is a way of trusting your own judgment about your health, even when your partner's account of the affair is still unclear.
The shame of the clinic visit
Readers who have been through this describe the same feeling in different words: humiliation at being tested for choices they never made, and embarrassment at answering personal questions because of someone else's secret decisions.
Name that feeling plainly, and put it where it belongs. The embarrassment belongs to the affair, not to you. You did not choose the risk. You are choosing the response. A clinician asking about your sexual history is doing their job, and a short, factual answer is enough. You do not owe them the story, and you do not need to explain or defend your relationship.
Kathy Nickerson, in The Courage to Stay, describes recovery as a series of phases, from suspicion and discovery through rebuilding. The clinic visit sits squarely in the discovery phase: it is uncomfortable, it is necessary, and it does not decide what comes next.
Sex and intimacy until you know more
Until you have results, and until your clinician has advised you on repeat testing, the safest choice is to pause sex with your partner, or to use condoms if you do have sex, and to ask your clinician what they recommend in your situation. This is a health decision, not a punishment, and it is worth saying so out loud, so it does not turn into a silent standoff.
Steven D. Solomon and Lorie J. Teagno, in Intimacy After Infidelity, write about rebuilding trust and intimacy as a process that needs emotional safety first. A pause for health reasons is part of that safety.
Trust is built in small moments, through turning toward a partner's needs rather than away from them. Respecting a health pause is one of those small moments. For more on rebuilding physical closeness once the health questions are settled, see Sex After Infidelity: Rebuilding Physical Intimacy.
Asking the partner who cheated to get tested too
You need a test. So does the partner who cheated, if the affair was sexual. Their test does not replace yours, and your negative result does not prove they are clear. Each of you needs your own clinician, your own tests, and your own results.
Ask directly, and keep it practical: "I am getting tested. I need you to get tested too, and to show me your results. This is about health, and I am not willing to guess."
Linda J. MacDonald, in How to Help Your Spouse Heal from Your Affair, writes about the unfaithful partner's task as tending their side of the fence: taking responsibility, being transparent, and doing the steady work that helps a betrayed partner feel safer. Getting tested, promptly and without argument, is one of the clearest examples of that work.
If your partner refuses testing, or gets angry about being asked, keep the health request simple: "I am asking for a health test after a sexual affair. I need you to do it. If you will not, I will make my own health decisions based on that." Gerald R. Weeks, Nancy Gambescia, and Robert E. Jenkins, in Treating Infidelity, describe an affair as a breach of a couple's agreement about exclusivity, and forgiveness as a process that follows repair, not a shortcut around it. A refusal to be tested is a refusal to take part in that repair.
Andrew G. Marshall, in How Can I Ever Trust You Again?, describes couples moving through stages from discovery to recovery. Testing sits at the start of that sequence. A partner who will not take the first step is telling you something about how far they are willing to go.
What a positive result does, and does not, prove
A positive result means you have an infection, and you need treatment and follow up care. It does not prove when you were infected, or who infected whom, or how many times your partner had sex with someone else. Some infections can be carried for a long time without symptoms, and some can be passed back and forth between partners. Your clinician can talk with you about what a result does and does not show, and about telling other partners who may need testing and treatment. Mayo Clinic notes that if you test positive, you should tell your sex partners, because they also need to be tested and treated.
A positive result also does not prove that the affair is still going on. It proves a health fact, and it needs a health response. The relationship questions still need their own answers, from full disclosure and from behavior over time, not from a lab result alone. A negative result does not erase the betrayal. It also does not settle whether to forgive, which remains your choice, including the choice not to forgive.
Michele Weiner-Davis, in Healing from Infidelity, emphasizes practical behavior changes and ending destructive patterns. Getting treatment, following through on repeat testing, and telling partners who need to know are practical behavior changes in that sense.
If you are the partner who cheated
This article is mainly for the betrayed partner, but if you are the partner who had the affair, the health steps are yours to take first, without being asked. Get tested yourself, promptly, and tell your partner you have done so. Do not present your results as proof that they have nothing to worry about, because your results do not answer their health question.
Tammy Nelson, in When You're the One Who Cheats, writes from the perspective of the partner who cheated, and about the confusion and the choices that follow. One of those choices is simple: own the health consequences of the affair, not only the emotional ones.
For a structured way to take responsibility in the first weeks, see I Cheated. What Do I Do Now? First 30 Days Accountability Plan.
Conclusion
Getting tested after a sexual affair is not about blame. It is about facts. You did not choose the risk, and you do not need to carry it silently.
The order is simple. If sex happened in the last three days, ask about PEP today. Otherwise, book a test now, tell your clinician what happened and when, ask when to come back for a repeat test, and pause sex or use protection until you know more. Ask your partner to get tested too, and watch what they do, not only what they say.
You can find out more about the first days after discovery in I Just Found Out My Partner Cheated. What Do I Do in the First 48 Hours.
A good place to start
This week, book one appointment with your clinician or a sexual health clinic, and write down three things to take with you: the date of your last sexual contact with your partner, any symptoms you have noticed, and the question, "When should I come back for a repeat test?" If sex with your partner happened in the last three days, make that call today and ask about PEP.
If it would help to think through what you heard, privately, before your next conversation with your partner, RenuuAI is a private AI recovery coach app that can help you work through a difficult question one step at a time, with guided AI sessions, a personalized recovery roadmap, and Recovery Pulse check-ins. It is not therapy, and it will not decide for you whether to stay or leave.
Sources
- Don-David Lusterman, Infidelity: A Survival Guide (1998, New Harbinger Publications)
- Caroline Madden, Blindsided by His Betrayal: Surviving the Shock of Your Husband's Infidelity (2016, Train of Thought Press)
- Kevin Skinner, Treating Trauma from Sexual Betrayal: The Essential Tools for Healing (2017, Growthclimate Incorporated)
- Scott Haltzman, The Secrets of Surviving Infidelity (2013, Johns Hopkins University Press)
- Debi Silber, Trust Again: Overcoming Betrayal and Regaining Health, Confidence, and Happiness (2020, Rowman and Littlefield Publishers)
- Kathy Nickerson, The Courage to Stay: How to Heal from an Affair and Save Your Marriage (2022, Dr. Kathy Press)
- Steven D. Solomon and Lorie J. Teagno, Intimacy After Infidelity: How to Rebuild and Affair-Proof Your Marriage (2006, New Harbinger Publications)
- Linda J. MacDonald, How to Help Your Spouse Heal from Your Affair: A Compact Manual for the Unfaithful (2010, CreateSpace Independent Publishing Platform)
- Gerald R. Weeks, Nancy Gambescia, and Robert E. Jenkins, Treating Infidelity: Therapeutic Dilemmas and Effective Strategies (2003, W. W. Norton and Company)
- Andrew G. Marshall, How Can I Ever Trust You Again?: Infidelity: From Discovery to Recovery in Seven Steps (2011, Bloomsbury Publishing)
- Michele Weiner-Davis, Healing from Infidelity: The Divorce Busting Guide to Rebuilding Your Marriage After an Affair (2017, Michele Weiner-Davis)
- Tammy Nelson, When You're the One Who Cheats: Ten Things You Need to Know (2019, RL Publishing Corporation)
- Centers for Disease Control and Prevention, "Getting Tested for STIs" (March 17, 2026) - https://www.cdc.gov/sti/testing/
- Centers for Disease Control and Prevention, "PEP" - https://www.cdc.gov/stophivtogether/hiv-prevention/pep.html
- Mayo Clinic Staff, "STD testing: What's right for you?" (July 16, 2025) - https://www.mayoclinic.org/diseases-conditions/sexually-transmitted-diseases-stds/in-depth/std-testing/art-20046019