Every few weeks, Dr. Vanessa Cullins, a board-certified obstetrician/gynecologist and vice president for medical affairs at Planned Parenthood® Federation of America, will be answering your questions here. To ask her your own question, click here.
Dear Dr. Vanessa,
I know that women can use emergency contraception to protect themselves from pregnancy after unprotected intercourse, what about STIs?
— Little Miss Hopeful
It is possible for women and men to protect themselves from some sexually transmitted infections after unprotected intercourse, but before a complete diagnosis can be made. This kind of protective treatment is sometimes called “post-exposure prophylaxis.” Prophylaxis is a prevention or protection against infection. (This is why the technical word for condoms is prophylactic.)
Protective treatment may be recommended by a clinician when someone is quite likely to have been exposed to certain infections through recent sexual contact. It can be attempted only for certain sexually transmitted infections, however. In the case of probable exposure to hepatitis B and HIV, the medication may prevent infection. This would be a true “prophylaxis.” “Prophylaxis” for hepatitis B and HIV must occur very quickly — in a few days –— following exposure.
The precise timing for protective treatment is different for hepatitis B than it is for HIV. Women and men who have been vaccinated against hepatitis B do not need to worry about exposure. To protect the unvaccinated against infection from possible exposure to hepatitis B, treatment must begin within 14 days. But the sooner treatment is started, the better.
Prophylaxis for hepatitis B is given in two ways. It can be provided in one injection of hepatitis B immune globulin. Or it can be given in a series of three injections of hepatitis vaccine over the course of six months. Treatment with the vaccine will protect against future exposure to hepatitis B.
To protect against infection from possible exposure to HIV, treatment should be started no later than three days — 72 hours — after potential exposure. The treatment is given with a combination of medications that must be taken orally for 28 days. Treatment with this “cocktail” is not a vaccine, however, and will not protect against future exposure to HIV.
Protective treatment for HIV is not recommended for people who have high-risk sex frequently or for drug users who share needles habitually. Such treatment would need to be constant and would pose health hazards.
In the case of chlamydia, gonorrhea, or syphilis, the medication is designed to treat an infection that may already be established, but before diagnosis is made. This is technically called “empiric” treatment. The use of antibiotics is effective at any time during the course of infection with chlamydia, gonorrhea, or primary syphilis.
If you would like to inquire about post-exposure treatment and STI testing, contact your health care provider or make an appointment with the Planned Parenthood health center nearest you.
Best wishes for your good sexual health,