Information

A sexually transmitted illness (STI) is a contagious disease that can be transferred to another person through sexual intercourse or other sexual contact. Many of the organisms that cause STIs live on the penis, vagina, anus, mouth, and the skin of surrounding areas.

Most of the diseases are transferred by direct contact with a sore on the genitals or mouth. However, some organisms can be transferred in body fluids without causing a visible sore. They can be transferred to another person during oral, vaginal, or anal intercourse.

Some STIs can also be transferred by nonsexual contact with infected tissues or fluids, such as infected blood. For example, sharing needles when using IV (in the vein) drugs is a major cause of HIV and hepatitis B transmission. An STI can also be transmitted through contaminated blood transfusions and blood products, through the placenta from the mother to the developing baby, and sometimes through breastfeeding.

The following factors increase your risk of getting an STI:

• Not knowing whether a partner has an STI or not
• Having a partner with a history of any STI
• Having sex without a male or female condom
• Using drugs or alcohol in a situation where sex might occur
• If your partner is an IV drug user
• Having anal intercourse

Drinking alcohol or using drugs increases the likelihood that you will participate in high-risk sex. In addition, some diseases can be transferred through the sharing of used needles or other drug paraphernalia.

Abstinence is an absolute answer to preventing STIs. However, abstinence is not always a practical or desirable option.

Next to abstinence, the least risky approach is to have a mutually monogamous sexual relationship with someone you know is free of any STI. Ideally, before having sex with a new partner, each of you should get screened for STIs, especially HIV and hepatitis B, and share the test results with each another.

Use condoms to avoid contact with semen, vaginal fluids, or blood. Both male and female condoms dramatically reduce the chance you will get or spread an STI. However, condoms must be used properly:

• Keep in mind that STIs can still be spread, even if you use a condom, because a condom does not cover surrounding skin areas. But a condom definitely reduces your risk.
• Lubricants may help reduce the chance a condom will break. Use only water-based lubricants, because oil-based or petroleum-type lubricants can cause latex to weaken and tear. Polyurethane condoms are less prone to breaking, but cost more than latex condoms. Using condoms with nonoxynol-9 (a spermicide) can help prevent pregnancy, but may increase the chance of HIV transmission because the spermicide can irritate the vaginal walls.
• The condom should be in place from the beginning to end of sexual activity and should be used every time you have sex.
• Use latex condoms for vaginal, anal, and oral intercourse.

Here are additional safe sex steps:

• Be responsible. If you have an STI, like HIV or herpes, advise any prospective sexual partner. Allow him or her to decide what to do. If you mutually agree on engaging in sexual activity, use use latex or polyurethane condoms and other measures to protect the partner.
• If pregnant, take precautions. If you have an STI, learn about the risk to the infant before becoming pregnant. Ask your provider how to prevent the developing baby from becoming infected. HIV positive women should not breastfeed their infant.
• Know your partner. Before having sex, first establish a committed relationship that allows trust and open communication. You should be able to discuss sexual histories, any previous STIs or IV drug use. You should not feel coerced or forced into having sex.
• Stay sober. Alcohol and drugs impair your judgment, communication abilities, and ability to properly use condoms or lubricants.

In summary, safe sex requires prior planning and good communication between partners. Given that, couples can enjoy the pleasures of a sexual relationship while reducing the potential risks involved.

For information about preventing pregnancy, see birth control and family planning.

References

Levine JP, Mraycak S, Wu J. Contraception. In: Rakel RE, ed. Textbook of Family Medicine. 7th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 37.

Lin JS, Whitlock E, O’Connor E, Bauer V. Behavioral counseling to prevent sexually transmitted infections: A Systematic Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2008;149:497-508.

Update Date: 4/5/2012

Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.