A sexually transmitted infection (STI) is an infection you can get by having sex with someone who is infected. Sometimes STIs are called “sexually transmitted diseases” (STDs) or “venereal diseases.”

There are more than 20 kinds of STIs, including

  • Chlamydia
  • Gonorrhea
  • Genital herpes
  • HIV/AIDS
  • HPV
  • Syphilis
  • Trichomoniasis

These diseases are caused by bacteria, parasites or viruses that are passed from one person to another during sexual contact with the penis, vagina, mouth or anus. While medicine can help cure STIs caused by bacteria and parasites, STIs caused by viruses have no cure. Some may go away on their own, but others, such as HIV, are permanent.

Both men and women can get STIs. Pregnant women with STIs can pass infection or other serious health problems to their baby.

STI Symptoms

Symptoms vary by type of STI, but can include:

  • Abdominal pain
  • Blisters, sores or warts around the genitals or rectum
  • Burning or itching around the opening of the penis
  • Burning or pain when urinating
  • Discharge from the vagina, penis or rectum
  • Fever
  • Itching in or near the vagina
  • Itching or bleeding of the rectum
  • Lower back pain
  • Nausea
  • Pain during intercourse
  • Pain during bowel movements
  • Painful or swollen testicles
  • Skin rash

Sometimes STIs don’t have any symptoms. But, it’s still important to get treated so the STI doesn’t get worse or cause other health problems.

If left untreated, some STIs can lead to:

  • Cancer of the cervix, vulva, vagina, penis or anus
  • Epididymitis in men, which can cause pain, fever and sometimes infertility
  • Infections of the reproductive system
  • Infertility
  • Pelvic inflammatory disease in women, which can cause infertility or other problems with pregnancy
  • Urinary tract infection

STI Diagnosis

If you think you have an STI, stop having sex until you can see a doctor and be tested and treated. You may be able to get free testing and treatment at your county health department.

To know if you have an STI, you will need lab testing. Sometimes the testing requires urine or blood samples. Other times it requires a sample from the penis, cervix or other affected area.

People who have an STI should notify all of their recent sex partners so they can be tested, too.

STI Treatment

Antibiotics and other medicine can help treat many STIs caused by bacteria and parasites, such as chlamydia and gonorrhea.

Medicine will not cure STIs caused by viruses, although it can help lessen symptoms and the risk of passing the disease to others. Some viral STIs, such as genital herpes, may go away on their own. Others, such as HIV, will never go away.

Treatment is especially important for pregnant women with STIs. Treatment can reduce the risk of passing the infection to the baby and causing other complications.

STI Prevention

The best way to protect yourself from STIs is to avoid sexual contact, or have sex only with a mutually monogamous partner who has been tested and is not infected. Using latex condoms can reduce – but not eliminate – your risk of getting an STI.

STI screenings are recommended for:

  • Sexually active women age 25 and younger, each year
  • All women with a new sex partner or multiple sex partners
  • Pregnant women, early in their prenatal care