The good news: Condoms can reduce the risk of contracting sexually transmitted infections (STIs). The trickier news: You’ve got to use condoms both consistently and correctly to reap the benefits of latex protection.   
In a study published in the journal Sexually Transmitted Infections, consistent and correct users of condoms reduced the risk of transmission by 59 percent for gonorrhea, chlamydia and trichomoniasis. However, those who used condoms consistently but incorrectly saw no statistical risk-reduction for transmission of these three non-viral STIs.

“Using a condom is not enough,” said the study’s lead author, Richard A. Crosby, PhD, a professor of public health at the University of Kentucky. “Like everything else, it has to be done right.” He identified five important pointers for correct condom usage:

  1. Put the condom on before inserting the penis into any orifice—that means avoid “dipping” (slipping the uncovered penis inside just for a while, then putting on a condom for prolonged intercourse and ejaculation).
  2. Keep it on until the deed is done.
  3. Do not reuse condoms. That includes between sex acts and if changing orifices—from oral to anal, for example.
  4. Protect against breakage by using plenty of water- or silicone-based lube (not oil-based!) and reapplying regularly if necessary.
  5. Avoid slippage by finding a condom that fits properly.

While the study covered only penile-vaginal sex, Crosby said its findings could translate to anal sex as well, although similar research is still needed among gay men.