STD Screening: The Basics

Updated January 15, 2025.

Everyone who is sexually active should be screened for sexually transmitted infections (STIs) at some point — but which tests, and when, depend on your personal risk factors. If you do test positive for an STI, there's good news: many STDs are curable, and all of them are treatable.

The term STI (sexually transmitted infection) is often preferred over STD (sexually transmitted disease) because there is less stigma attached to the word "infection". It’s possible to have an infection without symptoms, and the infection may cause disease (when you do experience symptoms) in the future. In the absence of symptoms, the only way to diagnose an STI is to screen for it.

• Human Papillomavirus (HPV): The most common STI in the U.S., this virus causes genital warts, although the lesions don’t appear in everyone who has HPV. It’s highly contagious and easily transmitted sexually or even by skin-to-skin contact. When genital warts are present, we can usually make a diagnosis from inspection, but additional testing is sometimes useful, and can include biopsy or colposcopy in people assigned female at birth (AFAB).
• Gonorrhea and Chlamydia: These infections are very common and are often grouped together because they’re screened for at the same time. The infection can be missed, particularly in people AFAB because the bacteria that cause them doesn’t always create symptoms. Infections are caused by oral, anal, or genital contact with someone else who has an infection.
• Syphilis: Syphilis is a bacterial infection passed from one person to another by oral, anal, or genital contact with infectious sores that are present during the initial stages of the infection. Because the sores are painless, the person who is infected often isn't aware of it.
• Herpes: There are two strains of the herpes virus: type 1 and type 2. Type 1 has traditionally been associated with oral herpes (also known as cold sores or fever blisters) and type 2 with genital herpes, but both strains can cause blisters in both areas. A person may have either strain of the virus but never show any symptoms, or they may have an “outbreak” with painful sores near his or her mouth, genitals, or anus. Herpes is most commonly transmitted via contact with infectious sores, but in some cases can be transmitted when the infected person has no symptoms at all. Because a person can be contagious even though no lesions are present, taking precautions only when there are visible lesions may not prevent spread of the infection to the partner.
• HIV: This viral infection, which affects the immune system, is transmitted via blood (e.g, in intravenous drug abusers who share needles with infected persons) or sexually, by having unprotected anal, oral, or vaginal sex.
• Hepatitis C: Hepatitis C is a viral infection that is transmitted most commonly through contact with blood or through skin exposure (e.g., sharing needles or coming into contact with an open wound or sore). Hepatitis C can also be contracted by having sex with someone who has hepatitis C; the risk is about 1 transmission per 190,000 sexual occurrences. This infection can cause chronic liver disease and liver cancer.
• Hepatitis B: Hepatitis B is also a viral infection, transmitted by blood or sexual fluids, that can cause liver disease.

Getting a screening test means that we look for an infection when you may not have any symptoms. Just like you get a mammogram, or screen for colon cancer, it’s also important to screen for sexually transmitted infections if you're sexually active. There are no exact recommended times or tests that we recommend for everyone. These testing recommendations depend on your lifestyle and sexual practices.

Most importantly, get tested to protect yourself, your partner(s), and to stay informed. Getting a diagnosis can alert you to an infection you may not know you had (e.g. many people hepatitis C, probably about 1 million in the U.S., have no idea they have been infected), or that may have long-term effects like infertility. It can also allow you to start treatment if you do have an infection, and create peace of mind when you think you may have been at risk.

There are plenty of tests that make staying informed accessible, but there’s no single test for every STI. Most tests require a urine or blood sample, or a swab of the area where the infection might be present. There are also rapid HIV tests you can buy for home use; results are available in about 20 minutes.

People often say, “Just test for everything.” While that might seem to make sense initially, it’s important to talk to your health care provider about your specific risk factors and lifestyle. There are a few downsides to testing for everything that are important to consider. First of all, tests can be expensive, and in a few cases, such as blood testing for herpes, a positive test can be a false positive. False positives may result in unnecessary anxiety when there may be virtually no risk of transmission and no required treatment.

Here are some instances that would prompt a screening test:

• You’re sexually active. Everyone who is sexually active (even if you’ve only ever had one partner and always use protection) should be screened at some point. It's recommended for all sexually active adults to be tested for HIV, hepatitis B, and hepatitis C at least once in their lifetime. Sexually active adults should also consider gonorrhea, chlamydia, and syphilis screening, depending on their particular situations.
• You’re having unprotected sex. If you’ve had or want to start having sex — vaginal, anal, or oral — with a new partner, without a condom, it’s a good idea to get tested. Here’s how long after exposure we can get a reliable test result:
  • 2 weeks: gonorrhea and chlamydia
  • 3 weeks to 3 months: syphilis
  • 4 weeks to 6 months: HIV, hepatitis C and B

You might be asking, “What about herpes?” We don’t recommend screening for the herpes virus for most people. We recommend testing if you have an outbreak of sores or blisters in the mouth or genital area.

• You're involved in a relationship that makes it more likely for you to get an STI. These factors include having a partner with a chronic infection such as HIV or hepatitis C or B, being in an open relationship or having multiple sex partners, or engaging in intimate contact with someone who is paid for sex or using intravenous drugs. It is recommended to consult with your healthcare provider about how frequently you should be screened based on your specific circumstances.
• You’ve had an infection in the past. You may be more likely to have in infection again, so it’s a good idea to be screened, about 3 months after you’ve been treated, if you are sexually active.
• You have symptoms. This is a good time to have a discussion with your health care provider. Your symptoms and history will allow you to make the best choice about the most informative tests to look for possible causes of your symptoms.

Still have questions? Make an appointment to talk to your PCP today in our judgment-free office.