Chlamydia — symptoms, testing and treatment
Reviewed by the My London Pharmacy clinical team, Zeenah Araim, Pharmacist Independent Prescriber
·29 July 2026
·6 min read
Quick answer
Chlamydia is a common bacterial STI that often causes no symptoms, so testing matters. It is diagnosed from a simple urine sample or swab and treated with a short course of antibiotics. Recent partners should also be tested, and it is important to avoid sex until treatment is complete.
What chlamydia is
Chlamydia is one of the most commonly diagnosed sexually transmitted infections in the UK, caused by the bacterium Chlamydia trachomatis. It is passed on through unprotected vaginal, anal or oral sex, and through sharing sex toys that have not been washed or covered with a new condom. It can also be passed from a pregnant person to their baby during birth, which can affect the baby's eyes or lungs, so it is checked for in pregnancy where relevant.
Because chlamydia is so widespread, particularly among people under 25, it is nothing to feel embarrassed about. It is a routine part of sexual health, and it responds well to treatment. The main challenge is that many people carry it without knowing, which is why regular testing is so valuable. The infection does not spread through everyday contact such as hugging, sharing towels, toilet seats or swimming pools, so there is no need to worry about passing it on in those ways.
Understanding a little about how chlamydia behaves helps take the anxiety out of it. It is a bacterium, which means it can be cleared with the right antibiotics, and catching it early keeps things simple. The sections below explain how to recognise it, how testing works, and what treatment involves.
Recognising the symptoms
Around seven in ten women and half of men with chlamydia notice no symptoms at all. When symptoms do appear, they usually start one to three weeks after exposure, though sometimes later, and they can be easy to dismiss as something minor.
In women, possible signs include unusual vaginal discharge, pain when passing urine, bleeding between periods or after sex, and lower tummy pain. In men, symptoms can include discharge from the penis, discomfort when urinating, and pain or tenderness in the testicles. If the infection affects the rectum, it may cause discomfort, discharge or bleeding, while an infection in the throat or eyes can cause irritation, though these are often silent.
Because symptoms are often absent or mild, they are not a reliable guide, and their absence certainly does not mean there is no infection. This is the single most important thing to understand about chlamydia: you cannot tell by how you feel. A test is the only way to know for certain, which is why screening is recommended even when everything seems fine.
How testing works
Testing for chlamydia is straightforward and painless. For women, a self-taken vaginal swab is usually recommended, which most people can do themselves in private. For men, a first-pass urine sample is typically used, meaning the first part of the urine stream after not passing urine for an hour or so. Swabs can also be taken from the rectum or throat where relevant, which matters if you have had anal or oral sex, as an infection at those sites can be missed if only urine is tested.
Samples are analysed using a highly accurate laboratory technique that detects the bacteria's genetic material, and results are usually available within a few days. Regular screening is advised if you are under 25 and sexually active, have a new partner, or have had unprotected sex. In England, the National Chlamydia Screening Programme encourages routine testing for young people, reflecting how common the infection is in this age group.
Testing is discreet and confidential, and a clinician can advise on which samples are appropriate for your circumstances. It is often sensible to test for other STIs at the same time, as they can occur together, and doing so gives you a fuller picture of your sexual health in one straightforward step.
How chlamydia is treated
Chlamydia is treated with antibiotics, and treatment is very effective when taken correctly. The current first-line treatment in the UK is a course of Doxycycline for Chlamydia, usually taken twice daily for seven days. This is preferred because it works well against chlamydia and related infections.
Where doxycycline is not suitable, for example in pregnancy or for people who cannot take it, a single dose of Azithromycin may be recommended instead, sometimes followed by a further course. A clinician will confirm which option is appropriate for you and check for any interactions or allergies before prescribing.
It is important to complete the full course, even if you feel well, and to avoid sex, including with a condom, until seven days after treatment finishes. This helps prevent the infection being passed back and forth.
Partners and retesting
Chlamydia is easily passed between partners, so anyone you have had sex with recently should be tested and treated, even if they have no symptoms. This is known as partner notification, and sexual health services can help arrange it confidentially if you prefer not to raise it yourself.
A repeat test is generally advised around three months after treatment for people under 25, as reinfection is common. If symptoms return or you have unprotected sex with a new partner, testing again is sensible.
Why treatment matters
Left untreated, chlamydia can lead to more serious problems. In women, it can spread to the womb and fallopian tubes, causing pelvic inflammatory disease, which is linked to long-term pelvic pain, ectopic pregnancy and reduced fertility. In men, it can occasionally cause inflammation of the testicles.
The reassuring news is that these complications are largely preventable with prompt testing and treatment. Catching and clearing the infection early keeps the risks low, which is why a quick, discreet test is always worthwhile if there is any chance of exposure.
Reducing your risk
Using condoms consistently for vaginal, anal and oral sex significantly lowers the chance of passing on or acquiring chlamydia, and they remain one of the most effective everyday protections against a range of STIs. Covering shared sex toys and washing them between uses also helps. Regular testing between partners, and testing with a new partner before stopping condoms, are practical habits that protect your sexual health.
There is no lasting immunity after chlamydia, so it is possible to catch it again even after successful treatment. This is not a reflection on you; it simply means the same everyday precautions continue to matter. Building testing into your routine, without judgement, is one of the simplest ways to stay in control of your health.
If you would like to talk through your risk, arrange a test, or discuss treatment discreetly, a clinician can help you decide the right approach for your circumstances. Looking after your sexual health is a normal, sensible part of overall wellbeing, and support is available whenever you need it.
Frequently asked questions
How soon after treatment can I have sex again?
Wait until seven days after you and your partner have finished treatment. If you were treated with a single dose, wait seven days from that dose to avoid passing the infection back and forth.
Can chlamydia go away on its own?
It is not safe to rely on this. Untreated chlamydia can persist and lead to complications such as pelvic inflammatory disease, so treatment with antibiotics is always recommended.
Will I know if I have chlamydia?
Often not. Most people have no symptoms, which is why regular testing is important, especially with a new partner or if you are under 25.
Do I need a test after treatment?
A test of cure is not routinely needed for uncomplicated chlamydia, but a repeat test around three months later is advised for younger people because reinfection is common.
Can I be treated without seeing anyone in person?
In many cases a clinician can assess your symptoms and history through an online consultation and, where appropriate, arrange testing and treatment discreetly.