What does Chlamydia look like? Signs you can see and signs you can’t

Chlamydia is a bacterial infection passed on through vaginal, anal and oral sex, and by sharing sex toys. It is a common sexually transmitted infection (STI), and the World Health Organization notes that many people with Chlamydia have no symptoms or only mild symptoms.

That is why it is often called a silent STI. Left untreated, it can lead to pelvic inflammatory disease, pain and swelling in the testicles, and problems with fertility. The good news is that it is simple to test for and straightforward to treat with a short course of antibiotics.

Most of the time, Chlamydia looks like nothing at all. You can’t see it in a partner either.

• In the genitals, when it does show: stinging or burning when urinating, a discharge from the penis, a change in vaginal discharge, bleeding after sex or between periods, or pain and swelling in the testicles.
• In the throat and rectum: usually nothing to see. In the rectum there may be fullness, pain, discharge or bleeding.

With no symptoms, you can test from 14 days after the sexual contact you are worried about. That is the window period for our Chlamydia tests, and our guide to when you can test for Chlamydia explains the timing.

Chlamydia infects the lining of the urethra, the cervix, the rectum and the throat. The inflammation it causes is often too mild to notice, and these surfaces are out of sight.

Any discharge can be slight enough to miss, and a little bleeding or discomfort is easy to mistake for something else. Feeling well and seeing nothing do not rule Chlamydia out, so a new partner or sex without a condom is reason enough to test.

No, though we understand why people try. Even a doctor needs a test to tell Chlamydia from other infections, because their signs overlap:

• Gonorrhoea can cause a white, yellow or green discharge.
• Trichomonas can cause a frothy yellow or green vaginal discharge with a fishy smell, or a thin white discharge from the penis.
• Thrush and urine infections are not STIs, but Thrush can cause a thick white discharge, and both can cause a burning feeling when passing urine.

When symptoms appear, they usually do so two to six weeks after infection, and sometimes later. Our guide to what Chlamydia discharge looks and smells like describes another common sign.

Symptoms in men

Men may notice a burning feeling when passing urine, which is by far the most common sign. There may also be a white, cloudy or watery discharge from the tip of the penis, sometimes no more than a drop, or pain and swelling in the testicles.

Symptoms in women

Women may notice a burning feeling when passing urine, or a vaginal discharge that is different from usual, sometimes yellowish. Bleeding after sex or between periods and pain low in the abdomen are the other signs.

Symptoms in the throat and rectum

Chlamydia in the throat or rectum is usually silent. The only sign in the throat may be a sore throat, and in the rectum the signs are fullness, pain, discharge or bleeding. See our guide to oral Chlamydia.

A urine sample does not test the throat or rectum. If you have given oral sex or received anal sex, add a throat or rectal swab to your test.

Whatever the symptom, it is a reason to test now rather than wait for the window period to pass. Sudden or severe pain in a testicle or low in the abdomen needs urgent medical care first.

• An early negative result needs repeating. If you test before 14 days have passed and the result is negative, a second test from day 14 is the one that counts.
• Condoms, or a break from sex, protect a partner until you have your result. Chlamydia can be passed on whether or not you have symptoms.
• Think about what else you want checked. HIV and Hepatitis B need a blood sample and have a 28-day window period, so a blood test at day 28 covers both.
• Talk to your partner. Current and recent partners of anyone who tests positive need testing too, and your online patient area lets you tell them by name or anonymously.

For genital symptoms, our Comfort Screen checks for Chlamydia, Gonorrhoea, Trichomonas and several other STIs from a single urine sample. If you need an answer today, our instant test for Chlamydia and Gonorrhoea uses a genital swab and gives a result in the clinic in under 30 minutes. It is less sensitive than a laboratory (PCR) test, especially if you have no symptoms, so a negative result is best confirmed with a laboratory test.

You can test at one of our private clinics across the UK, where most appointments take around 10 to 15 minutes and many are available the same or next day, or order a home test kit, which arrives in plain packaging with free return postage.

Results are reported to your secure online patient area within two working days of your sample reaching the laboratory, or three with a home test kit. If anything is found, we can arrange a doctor’s consultation and help you get treatment. If nothing is found and your symptoms continue, we can arrange a consultation too.

Everything is confidential and anonymous, and our Patient Care Team is available 24/7 on 020 7099 0955.

Do Chlamydia symptoms come and go?

Yes, Chlamydia symptoms can come and go. Pain or discharge can fade after a few days, but that does not mean the infection has gone. See our guide to Chlamydia symptoms that come and go.

Does Chlamydia cause a rash, spots or sores?

No, Chlamydia does not usually cause a rash, spots or sores. These have several possible causes, including Herpes, Syphilis and Genital Warts, and many other causes will not be STIs. Tell us what you have noticed when you book, and we will help you choose the right test. If there is doubt about what your rash is, there is no substitute for a medical opinion.

Most of the time, Chlamydia looks like nothing at all, and when it does show, only a test can tell it from other infections. With symptoms, you can test today. With none, you can test from 14 days after sex.

Whatever your situation, there is a next step. Take control of your sexual health and book a confidential Chlamydia test with Better2Know, online or by phone.

Medical review. This article was medically reviewed by Dr Steve Chapman, a doctor with a wealth of clinical experience in the field of STIs, on 15 October 2026. Better2Know content is reviewed for clinical accuracy before publication and updated when guidance or surveillance data changes. It is general information and not a substitute for personal medical advice.