Chlamydia is a bacterial infection. It is a sexually transmitted disease (STD). In fact, it is one of the most common STDs in the US. It is most common among sexually active teens and young adults.

This infection is caused by bacteria known as Chlamydia trachomatis. It is passed from an infected partner during sex. This can happen during oral, vaginal, or anal sex.

Factors that increase your chance of chlamydia include:

• Age: 15-25 years old
• Multiple sex partners
• Having sex without a condom
• History of sexually transmitted diseases

It is possible to have this infection and have no symptoms. Many people do not know they are infected. If symptoms do occur, they usually appear within 1-3 weeks of exposure.

Symptoms include:

• White or clear discharge from the penis
• Painful sensation while urinating

• Increased or abnormal vaginal discharge
• Strong vaginal odor
• Vaginal redness or irritation
• Painful urination
• Unusual vaginal bleeding
• Pain or bleeding during or after sex
• Abdominal pain

Pregnant women can also pass chlamydia to their newborns. This can happen during birth. It may cause conjunctivitis or pneumonia in the baby.

The symptoms can be very similar to another STD, gonorrhea. Your doctor will look for the specific bacteria. A swab test from the discharge of the penis or the cervix may be done. It is the most reliable method of detection for this bacteria. A urine sample may also be used. You may also be tested for others STDs, including HIV.

This infection is treated with antibiotics.The most commonly prescribed antibiotics are:

• Azithromycin (eg, Zithromax, Zmax)
• Doxycycline (eg, Vibramycin and others)

It is important that you and your partner both be treated before you have sex again. All of the medicine must be taken as directed. If you still have symptoms after the medicine is finished, you may need to be tested again.

Untreated chlamydia can have serious results:

• Testicles—epididymitis, a painful condition of the testicles that may lead to infertility
• Urethra—inside may become scarred; can make urinating difficult
• Prostate—inflammation of the prostate gland (prostatitis)
• Joints—inflammation of the joints (Reiter's syndrome)
• Rectum—inflammation of the rectum (anal intercourse)

• Reproductive organs—pelvic inflammatory disease (PID); may increase the risk of infertility or a tubal pregnancy
• Rectum—inflammation of the rectum (anal intercourse)

If you are diagnosed with chlamydia, follow your doctor's instructions.