What does the colour and texture of discharge tell you?
Colour, texture and smell narrow down the likely cause, though only a swab confirms it. Trichomoniasis typically produces a frothy, yellow-green discharge with a strong odour. Chlamydia and gonorrhoea can both cause yellow or yellow-green discharge, sometimes thicker with gonorrhoea. Bacterial vaginosis (BV) causes a thin, greyish-white discharge with a fishy smell, especially after sex. Thrush causes a thick, white, cottage-cheese-like discharge with intense itching but usually little smell.
Treat the table as a guide to common patterns rather than a diagnosis.
Why does trichomoniasis cause frothy, yellow-green discharge?
Trichomoniasis is caused by a small parasite, Trichomonas vaginalis, and is one of the most common curable STIs. Classically it causes frothy, yellow-green discharge with a strong odour, along with vulval soreness, itching and pain when you pee or have sex. Not everyone gets symptoms: up to half of infections are thought to cause no noticeable signs at all. Once diagnosed, it's easily cured with a short course of antibiotics, and both partners are treated together to stop it coming back.
Could it be gonorrhoea or chlamydia instead?
It could, and colour alone can't separate them from trichomoniasis. Gonorrhoea discharge is often thicker and can be tinged yellow-green. Chlamydia discharge is usually milder and sometimes barely noticeable. Both are frequently symptom-free, chlamydia especially, and both show up on the same swab or urine sample. Left untreated, either can spread upwards and contribute to pelvic inflammatory disease, which is why a test is a better guide than symptoms.
What does grey, fishy-smelling discharge mean?
Grey or greyish-white discharge with a fishy smell, most noticeable after sex, is the typical pattern of bacterial vaginosis. BV happens when the normal balance of vaginal bacteria is disrupted and bacteria such as Gardnerella vaginalis overgrow. It isn't classed as a sexually transmitted infection, but it is more common in sexually active women and can be triggered by a new partner or by douching. Our Gardnerella test is a swab that identifies the bacterium, so it can be treated with the right antibiotic first time.
What does thick, white discharge mean?
Thick, white discharge like cottage cheese, with intense itching and soreness, is the usual pattern of thrush (vaginal candidiasis). It's caused by an overgrowth of Candida, a yeast that normally lives harmlessly in the vagina, and it isn't sexually transmitted. It can still look and feel close enough to other causes that a swab is worth doing for a first episode, or if it keeps coming back. Our fungal infection test checks for Candida so the right antifungal treatment can be given.
What does brown discharge mean?
Brown discharge is usually old blood that has taken longer to leave the body, most often just before or after a period. It can also follow sex, when the cervix is touched, or come from cervical ectropion, where the cells lining the cervix are more fragile and bleed easily. Less often, chlamydia or gonorrhoea inflames the cervix and causes spotting that shows as brown. If it keeps happening after sex or between periods, come in and have a clinician examine the cervix. Our guide to brown discharge after sex goes into more detail.
Is some discharge normal?
Yes. Clear to white discharge that changes in amount and consistency through your cycle is normal. It's worth getting checked when the colour shifts towards yellow, green or grey, or there's a new or strong smell. The same goes for discharge that comes with itching, soreness, pelvic pain or bleeding between periods. Our broader discharge guide covers how STIs affect discharge in men as well as women. If you're unsure whether what you're seeing is normal, a swab settles it either way.
Which samples are needed?
The clinician chooses the samples from your symptoms and the kind of sex you've had, so one visit can cover the likely causes.
How testing works at our Harley Street clinic
A vaginal swab is quick and causes little discomfort, and you can take it yourself or have a clinician collect it. Laboratory testing of that swab is what reliably tells trichomoniasis, gonorrhoea, chlamydia, BV and thrush apart.
Book a trichomoniasis test if your discharge is frothy or yellow-green, or a partner has been diagnosed: it's £120.63, with results within 3 working days. For a broader check, our screening packages for women cover chlamydia, gonorrhoea, HIV and syphilis from the Bronze tier upwards. The Gold and Platinum tiers add trichomoniasis. The visit is confidential, as with all our private STI testing in London.
If your discharge settles after treatment but keeps coming back, our colleagues at Gynae Clinic Harley Street have written a vaginal discharge guide. It covers recurrent and cyclical causes worth discussing with a gynaecologist.
Book a trichomoniasis test at 117a Harley Street.
References
- Vaginal discharge, NHS
- Trichomoniasis, NHS
- Bacterial vaginosis, NICE Clinical Knowledge Summaries
- Management of vaginal discharge, BASHH
- Vulvovaginal candidiasis, NICE Clinical Knowledge Summaries
