What are sexually transmitted infections (STIs)?

Sexually transmitted infections, commonly called STIs, are diseases that are spread by having sex with someone who has an STI. These conditions are also known as sexually transmitted diseases (STDs). You can get an STI from sexual activity that involves the mouth, anus, vagina, or penis.

STIs are serious illnesses that require treatment. Some STIs, like HIV, cannot be cured and are deadly. By learning more about STIs, you can learn ways to protect yourself from these diseases. STIs include:

What are the symptoms of sexually transmitted infections (STIs)?

Sometimes, there are no symptoms. If symptoms are present, they may include:

  • Bumps, sores, or warts near the mouth, anus, penis, or vagina
  • Swelling or redness near the penis or vagina
  • Skin rash
  • Painful urination
  • Weight loss, loose stools, night sweats
  • Aches, pains, fever, and chills
  • Yellowing of the skin (jaundice)
  • Discharge from the penis or vagina (Vaginal discharge may smell bad.)
  • Bleeding from the vagina other than during a monthly period
  • Painful sex
  • Severe itching near the penis or vagina
  • Discharge from the penis
  • Discharge from the vagina that is different than usual (different odor, color, amount, or associated with irritation)

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy