7 causes of vaginal infection & abnormal vaginal discharge
What causes vaginal discharge – what’s normal and what’s not?
- Vaginal discharge is a natural fluid or mucus that keeps the vagina moist and protects it from infection.
- It tends to be white or clear, and normally doesn’t have an odour.
- Women often notice that their vaginal discharge changes naturally throughout the month- becoming thin and clear around the time of ovulation, and thicker in the second half of the month, before a period.
- However, if it changes noticeably in amount, colour or odour, it may mean there is an infection present.
- Several types of vaginal infection can lead to abnormal vaginal discharge:
Types of Vaginal Infection
Thrush (Candida)
Thrush (or candida to use its medical name) is a yeast infection. It can occur anywhere in the body, but prefers warm and moist places. It can naturally live in the vagina and cause no problems, but sometimes it overgrows, leading to symptoms such as thick white vaginal discharge, and irritation or itch of the vagina and the vulva. Whilst it occasionally can get passed between sexual partners, it’s not an STI. Some women find they are more prone to thrush just after their period. A recent course of antibiotics is another common trigger. Your doctor can diagnose thrush by the typical symptoms and appearance, but may also perform a vaginal or vulval swab to confirm it. Choice of treatment includes topical antifungal creams or pessaries – these are available over-the-counter at any pharmacy. If symptoms don’t go away, it’s important to get a full STI check to rule out other types of vaginal infection.
Bacterial Vaginosis (BV)
A normal, healthy vagina is home to a variety of different bacteria. However, in BV the balance is disturbed, and an overgrowth of some of these bacteria occurs. It’s not entirely clear why this happens. Like thrush, it’s not a sexually transmitted infection. The most common symptom is abnormal vaginal discharge which is often white-grey in colour and may have a distinct fishy smell. Your doctor can diagnose it by the typical symptoms, and may also perform a vaginal swab. To get rid of BV, you can choose between oral antibiotic tablets or a topical vaginal cream.
Chlamydia, Gonorrhoea and Mycoplasma
These are STIs which can be spread by oral, anal and vaginal sex. In many cases there are no symptoms.
However, some women develop symptoms of vaginal infection or inflammation in the pelvis, including abnormal vaginal discharge which can be yellow or green, a burning sensation when passing urine, pelvic pain, pain during sex, or bleeding between periods. It’s important to diagnose these conditions, as even silent infection can lead to serious pelvic infection, reduced fertility and a higher risk of ectopic pregnancy.
Your doctor can confirm the diagnosis by taking a swab from the upper part of the vagina and/or via a urine sample. Oral antibiotics are used to treat these infections.
Trichomonas
Trichomoniasis is an STI caused by a microscopic parasite called Trichomonas vaginalis.
Symptoms tend to develop within a month of infection, although up to half of all infected women get no symptoms at all. It can cause abnormal vaginal discharge which tends to be yellow-green, and may be frothy and smelly. Inflammation and itch around the vagina may also occur, as well as discomfort passing urine. Like the other causes of vaginal infection mentioned above, it’s diagnosed by swab and treated with antibiotics.
Genital Herpes
Genital Herpes leads to painful blisters or ulcers on the vulva, rather than vaginal infection- but it may also cause some changes in vaginal discharge when a flare-up is happening, due to local inflammation.
If you have any concerns about abnormal vaginal discharge, speak to your GP or sexual health clinic. For further useful information on vaginal discharge and sexual heath, check out the Family Planning Victoria Website.
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Clinical review & governance
Medically reviewed by Dr Ali Zavery
Dr. Aliasgar Zavery BSc (hons) MBBS MRCGP FRACGP DCH Dr Aliasgar (Ali) Zavery is originally from Nottingham, England. He trained at Guy's, King's and St Thomas' Hospitals in London, qualifying in 2003. He worked as a GP partner…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
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