Trusted medical advice from the
American Academy of Family Physicians.


What is chlamydia?

Chlamydia (Chlamydia trachomatis) is a sexually transmitted infection (STI). STIs also are known as sexually transmitted diseases (STDs). Chlamydia is a bacterial infection that affects both men and women. Chlamydia also can be passed on to newborn babies by mothers during delivery.

Symptoms of chlamydia

In the early stages of the disease, there are often no symptoms. Most people don’t know they have it. Symptoms can appear 1 to 3 weeks after exposure to the bacterial infection. It can include:

  • Painful urination (a burning sensation).
  • Lower abdominal pain.
  • Painful sexual intercourse.
  • Vaginal discharge in women.
  • Irregular periods in women.
  • Discharge from the penis in men.
  • Pain in the testicles in men.
  • Rectal pain, discharge, and bleeding for men and women who engage in anal sexual activity.
  • Reactive arthritis in both men and women (pain and inflammation of the joints that develops from an infection).

At its worst, chlamydia can damage a woman’s fertility, making it difficult to get pregnant. Also, it can cause an ectopic pregnancy (pregnancy that develops outside the womb). An extremely serious ectopic pregnancy can lead to a woman’s death.

What causes chlamydia?

Chlamydia is caused by engaging in unprotected sexual activity (vaginal, anal, and oral) with a person who has the infection. It also can spread just by touching an infected person’s genitals.

How is chlamydia diagnosed?

Your doctor will take a sample of bacteria from your genitals. For women, your doctor will swab (with a long cotton swab) the inside of the vagina. For men, he or she will swab the inside of the end of the penis. A urine test also may be required. This involves peeing in a cup provided by the doctor’s office. The urine sample is sent to a lab to be tested. If you are pregnant, your doctor may check you for chlamydia even if you have no signs of the disease. Chlamydia can be extremely dangerous to a newborn.

Can chlamydia be prevented or avoided?

You can reduce your risk of chlamydia by requiring a partner to use a condom. However, since the disease can spread just by touching your partner’s genitals, know the people with whom you have sexual contact. Limit your number of sexual partners. If you are thinking about using a spermicide for birth control, be aware that spermicides containing nonoxynol-9 can cause genital irritation. This can actually increase the risk of catching an STD. However, using a condom with nonoxynol-9 is better than not using a condom at all.

Women ages 25 and younger who are having any kind of sex (oral, vaginal, or anal) should be screened by their doctor on a regular basis for STIs. Women should avoid douching (a form of vaginal hygiene). It reduces the “good” bacteria in the vagina and increases the risk of infection.

If you have chlamydia, you should tell anyone you have sexual contact with.

Chlamydia treatment

If you have chlamydia, it can be treated with antibiotic medicine. Your doctor will prescribe a pill to be taken by mouth. Your partner also needs to be tested and treated. Tell your doctor if you are allergic to any type of antibiotic. Finish taking your entire antibiotic. Do not engage in sexual contact again for 7 days after you finish all of your medicine. Tell your doctor if you experience a fever or stomach pain while taking the medicine. Also, tell your doctor if you are or might be pregnant.

Living with chlamydia

If left untreated, chlamydia can spread to different parts of your body. This can cause additional harm. For example, if it spreads to your eyes, it can cause eye infections and blindness. In women, the infection can spread to the uterus and fallopian tubes (part of a woman’s reproductive system). The infection can cause scarring in this area. This can cause infertility or difficulty becoming pregnant. It also can cause an ectopic pregnancy. If the infection is passed on to a newborn baby through a vaginal delivery, it can cause pneumonia, an eye infection, and even blindness in the baby. In men, chlamydia can spread to the testicles and prostate. This can cause swelling, painful urination, fever, and lower back pain.

Questions to ask your doctor

  • Can chlamydia come back once it’s been treated and you haven’t had any more sexual contact?
  • Can antibiotics repair any permanent damage from chlamydia?
  • Is there any type of preventive medicine that can be taken before exposure to the disease?
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