What is chlamydia?

Chlamydia trachomatis is bacterial infection of semen or vaginal fluid. It is transmitted through sexual contact. This includes anal, vaginal, and oral sex. Chlamydia can still be passed on even when a man does not ejaculate. It is curable with doxycycline antibiotic.

Who is at risk of chlamydia infection?

Anyone who has unprotected sexual intercourse (vaginal, oral, or anal). It can also be transmitted by shared sex toys. Women can infect babies during childbirth.

How would I know I have chlamydia?

You may have not symptoms at all, so taking a test is the only way to know for sure (order a chlamydia test online).

What are typical symptoms of chlamydia?

These are genitourinary symptoms. Men can experience pain, discomfort, or swelling of the testicles, a burning sensation when passing urine, or a genitourinary discharge. Half of infected men have no symptoms. Symptoms for women are a vaginal discharge, bleeding after sexual intercourse, or between periods, a burning sensation when passing urine, and pelvis or lower abdominal pain. Three quarters of infected women have no symptoms.

What about symptoms elsewhere?

Chlamydia is spread by contact with infected genital fluid. The anus, throat, or eyes can be affected. Anal symptoms include soreness, with discharge that can be bloody. The throat may feel like a usual viral sore throat. If eyes are infected they become red, sore, and gritty with a discharge.

How long have I had this?

A chlamydia infection usually has no symptoms it is not possible to know how long you have been infected, the test cannot provide this information.

Why am I advised to tell my partner?

It is important that you let your current sexual partner know as they are at risk of having the infection too. They may then also be at risk of spreading the infection. You should also inform any other sexual partners you've had in the previous 6 months, for the same reasons.

How can I tell my partner, will they think I've cheated on them?

You may feel embarrassed, scared or angry. However it is important and respectful to let your partner know as soon as possible so they can get tested and treated. Remember that chlamydia often has no symptoms, so a diagnosis doesn't necessarily mean the infection was caught recently. You may not be sure when you were exposed. Many people are surprised how supportive their partner is, and how they appreciate being confided in.

How long after infection do symptoms appear?

Often there are no symptoms at all. When there are symptoms they can develop in one to three weeks, but can take many months.

If I had symptoms that have gone, does it mean my body has fought off the infection?

It's not safe to make that assumption. Symptoms can disappear despite the infection persisting. You could still be infected and could still pass it on.

Why is it important to treat chlamydia?

If left untreated chlamydia is unlikely to go away. It can be passed onto sexual partners and can cause serious harm. Women can get cervicitis (inflammation of the cervix with bleeding, discharge and painful sex) or pelvic inflammatory disease. This can result in permanent damage to the fallopian tubes, which may lead to infertility or (life threatening) ectopic pregnancy. Chlamydia also can cause a reactive arthritis. Men can suffer with urethritis (inflammation of the urethra: symptoms include discharge, pain passing urine, and sore skin at the penis tip), this can spread to the contents of the scrotal sac - epididymis and testicles. This causes pain, and in severe cases infertility. Men can also get a reactive arthritis.

How long does it take for my symptoms to clear?

On antibiotics, azithromycin or doxycycline, symptoms usually settle quickly. Pain on passing urine and discharge go within a week, pelvic or testicular pain can take two weeks and menstrual irregularities should improve by the next cycle.

My symptoms haven't cleared - why not?

There are several possible explanations. The symptoms could have a cause other than chlamydia. You can have more than one sexually transmitted infection at the same time, so you will need to be tested for other infections. There are also non-STI causes such as a lower urinary tract infection or, in women, endometriosis. You may have been re-infected with chlamydia if you had unprotected sex with an infected or partially treated partner. Rarely, the infection is resistant to a particular antibiotic treatment and therefore does not clear. Your GP or local GUM clinic would be able to help work out what is happening.

You may need a repeat chlamydia test (but wait 6 weeks after the first test).

Why can't I repeat the chlamydia test after I've taken my treatment to check it worked?

You can, but it takes up to 6 weeks for the test to go back to negative after an infection. If you re-test too early a positive result can be a sign of continuing or re-infection, but it's most likely to be positive from the initial infection, so it's not at all helpful.

If you are under 25 years of age, it is recommended to have a repeat test 3 months after treatment as a significant number of young people get repeat infections which are linked to an increased risk of complications.

My partner didn't get treated and we had sex, can I be re-infected?

Yes, it's best for both partners to be treated at the same time, and abstain from sex (that means no genital, oral or anal sex - even with a condom) for one week from the start of treatment, by which time the infection will have gone.

How do I take doxycycline?

Take two doses (100mg each dose) a day (ideally evenly spaced 12 hours apart) for one week. Gullet irritation is a risk with doxycycline. To avoid this swallow the capsules whole, taking them with (a glass of) water. This ensures they go straight into the stomach without sticking in the gullet. Taking them whilst upright, sitting or standing, will also help. For this reason don't take doxycycline just before bed.

There is evidence that unlike some other tetracycline antibiotics, doxycycline absorption is not significantly slowed when taken with a meal. If nausea and tummy upset is a problem when taken on an empty stomach, the advice is to take with food.

Does azithromycin also cure chlamydia?

Azithromycin was the first choice antibiotic to treat chlamydia until February 2019 when BASHH guidance was issued recommending a 7-day course of doxycycline as the first choice treatment based on recent data. Azithromycin is now recommended only for pregnant women and those with an allergy to doxycycline.

What if I vomit?

Just carry on with the course. Partially absorbing or missing just one doxycycline pill is unlikely to make a difference - missing several can result in treatment failure. Continue taking the doxycycline with food.

What if forget a dose of doxycycline?

Take the forgotten tablet as soon as you remember. If that is not until the next dose is due, do not take a double dose. Missing doses decreases the effectiveness of treatment and it may fail.

Does chlamydia cause cervical cancer?

No it does not. Infection with some strains of human papilloma virus (HPV) increases the risk of developing cervical cancer. Girls in the UK are now routinely vaccinated against them at age 12-13. Other strains of this virus are responsible for genital warts. HPV can be sexually transmitted.

What if I'm pregnant - will chlamydia affect the baby?

During delivery, the infection can spread to the newborn from the birth canal. It can cause eye infection or pneumonia. There may also be an association with preterm labour and low birth weight. Screening and treatment of chlamydia during pregnancy can prevent these complications. This is not part of the routine NHS antenatal screening. Doxycycline cannot be taken during pregnancy, but azithromycin is safe and effective.

If I have chlamydia, am I at risk of other sexually transmitted infections (STIs)?

Yes. By definition, having unprotected sex means risk of STI. As well as chlamydia, there are also genital warts, genital herpes, gonorrhoea, HIV, pubic lice, and syphilis. Like with chlamydia, gonorrhoea may well cause no symptoms, so being tested is the only way to really know. This can be done at your local sexual health clinic.

How can I protect myself against chlamydia?

Always use a condom - when used correctly the risk of transmission of chlamydia is much reduced. Before starting a sexual relationship (vaginal, anal, and oral) both partners should be tested for sexually transmitted infection and any positive result treated prior to sexual contact.

How often should I get tested for chlamydia?

As above, it is safest to get tested before starting a sexual relationship (vaginal, anal, and oral) so that any positive result is treated prior to sexual contact. NHS England recommend that if you are under 25 and sexually active you should get tested annually, as well as when you have a new partner.

Where can I get tested?

Sexual health clinics, a genitourinary medicine (GUM) clinics or GP surgeries provide free and confidential chlamydia testing. In England there is a national screening program for people under 25 years; test kits are available in many pharmacies, contraception clinics, or colleges. Home testing kits may also be purchased in some pharmacies and online.

Chlamydia treatment
Dr Tony Steele

Authored 12 November 2013 by Dr Tony Steele
MB ChB Sheffield University 1983. Former hospital doctor and GP.

Reviewed by Dr A. Wood, Dr B. Babor, Dr P. Hunt
Last reviewed 16 September 2019
Last updated 15 October 2021