Some of the most common STDs are listed here. It only takes one sexual contact with someone who has an STD to catch it. Girls and guys may have redness and itching around the genitals. Usually both partners need to be treated.
Girls can have a heavy, greenish-yellow frothy discharge and pain when urinating.
Guys don't usually have symptoms. Usually both partners need to be treated. Guys may feel a burning when urinating and have milky colored discharge from the penis. If not treated, chlamydia can cause infertility and other problems in girls and painful swelling of the scrotum in guys. Usually both partners should be treated.