A change in the way you smell is personal, and it can be hard to bring up, even with a doctor. Many women put off getting checked because they feel embarrassed, or because they assume the change is nothing.
Sometimes it is nothing. Vaginal odour shifts with your cycle, diet, exercise and stress, and most temporary changes settle on their own within a day or two. This page focuses specifically on smell; if unusual discharge is your main concern, our discharge guide covers that in more detail. If you already suspect something is wrong, walk-in testing is available seven days a week at our Harley Street clinic, and you do not need a GP referral.
Does chlamydia smell?
Chlamydia rarely produces a noticeable smell. When it does, the change is usually mild and easy to miss, and it's more often the discharge that changes than the smell itself. Chlamydia is the most common bacterial STI in the UK and is frequently asymptomatic (UKHSA, 2024), so a normal smell does not rule it out. A chlamydia test is the only reliable way to check.
What does a normal vaginal odour smell like?
Healthy vaginal odour is usually mild, slightly acidic or musky, and it varies between women and across the menstrual cycle. It should not be strong, fishy or foul.
The vagina's natural balance of lactobacillus bacteria keeps its pH acidic, around 3.8-4.5, which produces this mild baseline smell. Temporary changes are common after exercise, sex, or a long day in tight clothing, and these usually settle within a day or two on their own.
A change that persists, gets stronger, or comes with unusual discharge is worth having checked.
"Changes in vaginal odour are one of the most common reasons women visit our clinic. In the majority of cases, testing identifies a treatable cause within days."
Dr Hikmat Naoum, Consultant Gynaecologist, GMC 3047637
Which STIs and infections cause vaginal odour?
Not every infection that changes vaginal odour is sexually transmitted. Bacterial vaginosis is the most common cause of a fishy smell and is not classed as an STI. Trichomoniasis, and less often chlamydia or gonorrhoea, are confirmed STIs that can also change how you smell.
Bacterial vaginosis (BV)
BV is the most frequent cause of abnormal vaginal odour in women of reproductive age (NICE CKS, 2024). It produces a fishy smell that often gets stronger after sex and during your period. The smell comes from amines released when the usual lactobacillus bacteria are displaced by anaerobic organisms such as Gardnerella vaginalis.
BV is not classed as an STI, but it's more common in women with new or multiple partners, and in women who douche. It often comes with a thin, greyish-white discharge alongside the smell.
A Gardnerella PCR swab tests for BV and costs £120.63, with results within 3 days. A dedicated bacterial vaginosis swab is also available at £105.
Trichomoniasis
Trichomoniasis is caused by a parasite, Trichomonas vaginalis, and is a confirmed STI. It produces a strong, musty or fishy odour, distinct from the BV smell, usually with a yellow-green, frothy discharge.
Many women with trichomoniasis also notice soreness, itching or discomfort passing urine or during sex, though up to half have no symptoms at all (BASHH, 2024).
A trichomoniasis PCR test costs £120.63, with results within 3 working days. Treatment is a short course of antibiotics prescribed by the doctor.
Chlamydia and gonorrhoea
Chlamydia and gonorrhoea are grouped here because they're usually tested on the same sample and rarely produce a distinctive smell of their own. When gonorrhoea does change how you smell, it's more often through a change in discharge colour than odour on its own, and symptoms frequently overlap with other infections, which is why testing is more reliable than trying to match symptoms.
A combined chlamydia and gonorrhoea PCR test costs £104, with results within 3 working days.
Forgotten tampon or foreign body
This is more common than you might expect, and it produces one of the strongest and most unpleasant vaginal odours of all. A retained tampon creates the conditions for rapid bacterial growth. If you notice a sudden, severe smell you can't otherwise account for, a forgotten tampon is worth considering. A GP or walk-in clinician can check and remove it quickly.
Vaginal odour and STIs at a glance
This table is a starting point, not a diagnosis: several of these overlap, and some infections cause no smell at all.
This table is a guide, not a diagnostic tool. Testing is the only way to confirm the cause, and our women's STI screening package covers most of these in a single visit if you would rather test for several at once.
When vaginal odour is not an STI
Not every odour change is infection, and not every infection is sexually transmitted.
Thrush (vaginal candidiasis) produces a yeasty smell with thick, white, cottage-cheese-like discharge. It's caused by an overgrowth of Candida and is not sexually transmitted, though it's more common after antibiotics, during pregnancy, and in women with diabetes.
Hormonal changes during the menopause can thin the vaginal walls and shift the bacterial balance, sometimes producing a new or different smell. This isn't caused by infection, but it can still be worth discussing with a clinician.
Poor hygiene is rarely the cause. Over-washing with scented products, douching, or using vaginal deodorants disrupts the natural bacterial balance and tends to make odour worse. The vagina is self-cleaning; warm water externally is enough.
When to see a clinician
Get assessed if any of the following lasts more than a few days: a persistent fishy or foul smell, a change in discharge colour or texture, itching, soreness or burning, pain during sex or when you urinate, or bleeding between periods.
If you've had a new sexual partner in the past three months, testing for STIs alongside BV and thrush is sensible even if a change in smell is your only symptom.
Our Silver package (£375 for women) covers chlamydia, gonorrhoea, HIV, syphilis, Mycoplasma genitalium, Ureaplasma, Gardnerella and herpes I and II, plus a vaginal swab for candida and BV. The Gold package (£490) adds trichomoniasis and hepatitis B and C. Either checks for STI and non-STI causes in one visit. See our women's STI packages for the full range.
How we test
Walk-in testing is available seven days a week at our Harley Street clinic, when there is capacity. No GP referral is needed. All samples are processed by UKAS-accredited laboratories.
You do not need to give your real name at our anonymous sexual health clinic, and we accept cash payment.
For vaginal odour concerns, we typically recommend a combination of swab and blood testing. A swab screens for BV, thrush, trichomoniasis and other vaginal infections. Blood tests cover syphilis, HIV and herpes antibodies.
Results for blood tests come back in about 24 hours, and urine and swab results within 3 working days. Turnaround starts when your sample reaches the lab, and samples reach the lab the same day, including weekend samples. If a result is positive, our doctors can prescribe treatment the same day.
If you need everything back faster, the FAST Screen returns all results in 6 hours: FAST Screen Simple (£350) covers HIV, syphilis, chlamydia and gonorrhoea, and FAST Screen Complex (£450) adds hepatitis B and C.
References
- BASHH (2024). UK National Guideline for the Management of Bacterial Vaginosis.
- BASHH (2024). UK National Guideline on the Management of Trichomonas vaginalis.
- NICE CKS (2024). Bacterial vaginosis: Diagnosis and management.
- NICE CKS (2024). Vaginal discharge: Assessment and causes.
- NHS (2024). Vaginal discharge.
