Sexually Transmitted Infections (STIs)

What are Sexually Transmitted Infections (STIs)?

Sexually transmitted infections (STIs), are generally acquired by sexual contact. The organisms that cause sexually transmitted diseases may pass from person to person in blood, semen, or vaginal and other bodily fluids.

Some such infections can also be transmitted nonsexually, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.

It's possible to contract sexually transmitted diseases from people who seem perfectly healthy — people who, in fact, aren't even aware of being infected.

Sexually transmitted infections (STIs) have a range of signs and symptoms. That's why they may go unnoticed until complications occur or a partner is diagnosed.

Signs and symptoms that might indicate an STI include:

Sores or bumps on the genitals or in the oral or rectal area

Painful or burning urination

Discharge from the penis

Unusual or odd-smelling vaginal discharge

Unusual vaginal bleeding

Pain during sex

Sore, swollen lymph nodes, particularly in the groin but sometimes more

widespread

Lower abdominal pain

Signs and symptoms may appear a few days to years after exposure, depending on the organism.

Sexually transmitted infections can be caused by:

Bacteria (gonorrhea, syphilis, chlamydia)

Parasites (trichomoniasis)

Viruses (human papillomavirus, genital herpes, HIV)

When to see a doctor

See a doctor immediately if:

You are sexually active and you believe you've been exposed to an STI

You have signs and symptoms of an STI

Make an appointment with a doctor: