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Common vaginal infections

Vaginal infections occur when bacteria, fungi or viruses grow in and around the vaginal area.

  • About vaginal infections
  • Symptoms
  • Causes
  • Diagnosis
  • Common vaginal infections
  • Safer sex
  • Further information
  • Sources
  • Related topics

About vaginal infections

Certain types of bacteria live naturally inside the vagina. They produce acid, which helps to fight off other bacteria, as well as viruses and fungi that don't normally live in the vagina. Anything that lowers the acidity of the vagina can cause a vaginal infection.

It's normal and healthy for a woman of childbearing age to have a vaginal discharge. The amount and colour of the discharge can change during your menstrual cycle, sexual excitement and pregnancy.

Vaginal infections are common. For example, half to three-quarters of women will have thrush in their lives and nine to 28 percent will experience bacterial vaginosis.


Symptoms of a vaginal infection include:

  • an unpleasant fishy smell
  • pain during sex
  • bleeding after sex
  • abdominal pains
  • redness, swelling, lumps, blisters, or ulceration of the vulva (the skin around the outside of the vagina) or anus
  • pain when passing urine

It's important that you see your doctor if you have any of these symptoms.


Vaginal infections occur when bacteria, fungi or viruses grow in and around the vaginal area. This is usually because they are transmitted, for example during sexual intercourse.

Sometimes they are already present and living harmlessly in the vagina, but begin to grow more than usual. A common symptom of an infection is an unusual discharge, along with itchiness and soreness.

A foreign body, such as a forgotten tampon, can also cause infection and an unpleasant discharge from the vagina. Rarely, it can produce a life-threatening complication known as "toxic shock syndrome".


If you have any of the symptoms listed here, you should go to your GP, or your local GUM (genito-urinary medicine) or sexual health clinic. To diagnose a vaginal infection, your doctor may need to examine the skin around your vagina and/or the lining inside your vagina. An instrument called a speculum (which is also used for smear tests), is sometimes used. Your doctor may take a sample of discharge may using a swab, which looks like a long cotton bud. This is sent to a laboratory for analysis. You may also need to have a urine test, to look for signs of infection with the bacteria that cause chlamydia and gonorrhoea.

Common vaginal infections

The main types of common vaginal infection are as follows.


Almost all women have the fungus Candida albicans growing harmlessly on and in their body. A change in the vaginal environment can cause it grow excessively, causing thrush (vaginal candidiasis).

Possible triggers of thrush include:

  • pregnancy
  • menstruation
  • diabetes
  • taking the contraceptive pill
  • wearing tight underwear
  • taking antibiotics

Symptoms of thrush include irritation and soreness of the vulva. This is sometimes accompanied by a thick, white vaginal discharge that doesn't usually smell.

Women often self-diagnose thrush. Your pharmacist can give you advice on treatments to stop the infection.

Most infections respond to an antifungal treatment such as imidazole cream or pessaries (eg Canesten), or fluconazole (Diflucan) tablets, which are available from your pharmacist without prescription.

If the treatment doesn't work or the symptoms come back, you should see your GP. He or she may prescribe different antifungal drugs or a longer course of fluconazole tablets. There's no good evidence that treating a male partner helps, unless he has a rash or a sore penis.

To help prevent thrush, wear cotton pants and change them daily. Don't use perfumed soaps or feminine hygiene sprays, as these products can cause irritation that can trigger thrush. Vaginal douches aren't recommended to treat or prevent vaginal infections, including thrush. This is because they disturb the natural protective acidity of the vagina.

Bacterial vaginosis

Bacterial vaginosis (BV) is most common cause of vaginal discharge in women of childbearing age. It's caused when the bacteria normally found in the vagina (Lactobacillus) are overgrown by others (e.g. Gardnerella vaginalis), which are normally found in smaller numbers. Some women with BV don't have any symptoms at all - you may only discover that you have BV after a routine smear test.

Some women with BV have a thin and grey discharge with a fishy smell. Sometimes the vagina itches or burns.

BV symptoms can clear up without treatment and then come back. But if it's left untreated, BV can cause miscarriage, premature labour and pelvic inflammatory disease (PID). It can also increase the risk of the transmission of viruses, including human immunodeficiency virus (HIV).

The treatment for BV is an antibiotic called metronidazole. It's only available on prescription and comes as a cream, a gel or in tablet form. Even with treatment, the condition can come back.

BV is not a sexually transmitted disease, although there may be a link with having a new sexual partner or a high lifetime number of sexual partners. Male sexual partners don't need treatment.

The intra-uterine system (IUS or coil) seems to increase the risk of BV. Using some types of soap and shower gel that are very perfumed or harsh also seems to promote BV by causing irritation to the vagina.


Trichomoniasis is caused by a protozoan (a kind of parasite) called Trichomonas vaginalis. This parasite is transmitted during sex.

The characteristic symptom of trichomoniasis infection is a heavy, frothy, yellow-green, fishy-smelling discharge from the vagina. The infection can also cause discomfort during sex, vaginal itching, pain when passing urine and occasionally stomach pains. However, up to half of women with trichomoniasis don't have any symptoms.

Trichomoniasis can sometimes get better without any treatment but antibiotic treatment with metronidazole cures up to 95 percent of women. Symptoms are less common in infected men, so male partners should also be treated.

If you have trichomoniasis, your GP will refer you to a sexual health clinic.

Research has linked trichomoniasis infection with infertility, increased risk of transmission of HIV, premature labour, and low birth-weight babies.


Chlamydia is the most common sexually transmitted infection in the UK and it's getting more common. It's caused by the sexually transmitted bacterium Chlamydia trachomatis, which destroys the cells of the lining of the cervix and other tissues. It can cause pain when passing urine, bleeding after sex, long-term pelvic pain and infertility. It doesn't always produce an abnormal discharge and 70 to 80 percent of women and 50 percent of men with chlamydia don't get symptoms. This means that you can get chlamydia without knowing you have it.


Gonorrhoea is caused by infection with the bacterium Neisseria gonorrhoeae, which is passed on during sexual intercourse.

The main symptoms of gonorrhoea are vaginal discharge and pain passing urine; you may have no symptoms in the early stages.

Genital herpes

Genital herpes infection is caused by the herpes simplex virus being passed on during sexual contact. If you have the herpes simplex virus, it may lie dormant in your body for the rest of your life and it's common to get repeated attacks of genital herpes. These are generally milder than the first attack.

The chance of passing on the virus is higher while you are having an attack of genital herpes. However, you can also pass on the virus when you have no symptoms.

Genital warts

These are caused by the human papilloma virus (HPV), which makes cells grow abnormally. You can catch genital warts by touching someone who has them (skin-to-skin contact).

Genital warts appear as small round lumps on or around the genitals.

Safer sex

Chlamydia, gonorrhoea, herpes and trichomoniasis are all sexually transmitted infections (STIs) and are preventable. A condom provides good protection against many STIs.

Further information

fpa (formerly the Family Planning Association)



  • Candida - female genital. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 5 March 2007
  • Bacterial vaginosis. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 5 March 2007
  • Trichomoniasis. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 5 March 2007
  • Herpes simplex - genital. http://cks.library.nhs.uk, accessed 5 March 2007
  • Warts. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 5 March 2007
  • Sexually transmitted infections in primary care. The Royal College of General Practitioners. 2006. www.bashh.org
  • Management of genital chlamydia trachomatis infection. Scottish Intercollegiate Guidelines Network. 2000. www.sign.ac.uk

Related topics

  • Chlamydia
  • Genital herpes
  • Genital warts
  • Gonorrhoea
  • Sexually transmitted infections