A sexually transmitted infection (STI) is an infection that can be spread to another person through sexual contact. STIs include:

• Chlamydia
• Genital herpes
• Genital warts
• Gonorrhea
• Hepatitis
• HIV (human immunodeficiency virus)
• HPV (human papilloma virus)
• Syphilis

STIs are also called sexually transmitted diseases (STDs).

These infections are spread by direct contact with a sore on the genitals or mouth, body fluids, or sometimes the skin around the genital area.

Before having sex:

• Get to know your partner and discuss your sexual histories.
• Don't feel forced into having sex.
• Don't have sexual contact with anyone but your partner.

Your sexual partner should be someone who you know does not have any STI. Before having sex with a new partner, each of you should get screened for STIs and share the test results with each other.

If you know you have an STI such as HIV or herpes, let any sexual partner know this before you have sex. Allow him or her to decide what to do. If you both agree to have sexual contact, use latex or polyurethane condoms.

Use condoms for all vaginal, anal, and oral intercourse.

• The condom should be in place from the beginning to the end of the sexual activity. Use it every time you have sex.
• Keep in mind that STIs can be spread by contact with skin areas around the genitals. A condom reduces but does not eliminate your risk of getting an STI.

Other tips include:

• Use lubricants. They may help reduce the chance that a condom will break.
• Use only water-based lubricants. Oil-based or petroleum-type lubricants can cause latex to weaken and tear.
• Polyurethane condoms are less likely to break than latex condoms, but they cost more.
• Using condoms with nonoxynol-9 (a spermicide) may may irritate vaginal or penile tissue and thus increase the chance of HIV transmission.
• Stay sober. Alcohol and drugs impair your judgment. When you are not sober, you might not choose your partner as carefully. You may also forget to use condoms, or use them incorrectly.

Get tested regularly for STIs if you have new sexual partners. Many STIs have no symptoms, so you need to be tested often if there is any chance you have been exposed. You will have the best outcome and will be less likely to spread the infection if you are diagnosed early.

Consider getting the HPV vaccine to keep from getting the human papillomavirus. This virus can put you at risk for genital warts and for cervical cancer in women.

Chlamydia - safe sex; STD - safe sex; STI - safe sex; Sexually transmitted - safe sex; GC - safe sex; Gonorrhea - safe sex; Herpes - safe sex; HIV - safe sex; Condoms - safe sex

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Landovitz RJ, Del Rio C, Cohen MS. Prevention of human immunodeficiency virus infection. In: Goldman L, Cooney KA, eds. Goldman- Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 356.

Swygard H, Cohen MS. Approach to the patient with a sexually transmitted infection. In: Goldman L, Cooney KA, eds. Goldman- Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 264.

US Preventive Services Task Force; Krist AH, Davidson KW, et al. Behavioral counseling interventions to prevent sexually transmitted infections: US Preventive Services Task Force Recommendation Statement. JAMA. 2020;324(7):674-681. PMID: 32809008 pubmed.ncbi.nlm.nih.gov/32809008/.

Workowski KA, Bachmann LH, Chan PA, et al. Sexually transmitted infections treatment guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1-187. PMID: 34292926 pubmed.ncbi.nlm.nih.gov/34292926/.

Updated by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.