AIDS is the deadliest of sexually transmitted diseases (STDs), but other STDs are more prevalent and also serious if untreated. All are spread by unprotected sexual contact; male use of latex condoms can reduce the possibility of infection but not eliminate it.

Most STDs, including gonorrhea, chlamydia, and syphilis, are treatable with antibiotics, but some strains have developed immunity to penicillin and alternative treatments. If taking antibiotics, complete the prescribed course—an interrupted treatment may not kill the infection and could even help it develop immunity.

Herpes, a virus that causes small but irritating ulcers in the genital area, has no effective treatment. It is likely to recur, easily spread when active, and can contribute to cervical cancer. Hepatitis B, though not exclusively an STD, can spread through the mixing of bodily fluids such as saliva, semen, and menstrual and vaginal secretions. It can also spread through unsanitary medical procedures, inadequately sterilized or shared syringes, during body piercing, and similar circumstances. Like hepatitis A, it can cause liver damage but is more serious; vaccination is expensive but advisable for high-risk individuals.