A guy I had sex with a few weeks ago is telling me that he thinks he got an STD from me. A while ago, I had unprotected sex with someone, and I don't know if that person has an STD or not. How can I know if I have an STD without getting checked by a doctor? Or is that the only way to find out? – TJ* The only way to be sure about whether or not you have an STD is to get tested and examined at a doctor's office or health clinic. Many STDs don't have obvious symptoms. Lots of people don't even know they have an STD until their doctor discovers it. Even a bump that looks like an ingrown hair could be something more. When you go for your exam, tell the doctor or nurse practitioner that you had unprotected sex in the past. (Don't worry about how he or she will react — medical professionals are trained to help people, not judge them.) The doctor or nurse practitioner can check you for any STDs with a simple exam and a blood test or urine test. If it turns out that you do have an STD, the doctor or clinic can start treating you. It is really important to treat STDs as early as possible so that you stay healthy and don't have any complications. Because many STDs don't have symptoms, you won't be able to "see" that someone else has an STD either. That's why the best way to protect yourself and anyone you sleep with is to use a condom. And if you're having sex, get regular checkups and STD screenings. *Names have been changed to protect user privacy. Back to Articles Related Articles STDs (Sexually Transmitted Diseases) You've probably heard lots of discouraging news about sexually transmitted diseases. The good news is that STDs can be prevented. Find out how to protect yourself. Read More Is a Gynecologist the Same as a Primary Care Doctor? Find out what the experts have to say. Read More Gyn Checkups Girls should get their first gynecological checkup between ages 13 and 15. Find out what happens during a yearly gyn visit -- and why most girls don't get internal exams. Read More When Is it Time to Start Seeing a Gynecologist? Find out what the experts have to say. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.