Vaginal thrush is a common and annoying problem that affects three out of four women at some time during their life. Dr Sarah Brewer explains how to ease and prevent this irritating ailment

What causes it?
Thrush is caused by an overgrowth of a yeast, candida albicans, which is present in the vagina and on the skin of many women without causing any harm at all.

How do you get it?
Candida spores are widespread in the air and thrive when they land on warm, moist places, such as around our private parts. Although it is not classed as a sexually transmissible infection, it can sometimes be passed on during sexual intercourse if the male partner harbours candida spores under his foreskin.

What are the symptoms?
Symptoms of thrush vary and can include itching, soreness or burning, a yeasty smell, vaginal discharge, which is sometimes white and cottage cheese-like, and discomfort during urination and/or intercourse. The amount of discharge does not necessarily relate to the severity of symptoms, and some women find that dryness makes their symptoms worse.

Who is at risk?
Thrush symptoms are more likely around the time of a period, due to changes in the acidity of vaginal discharge. It is also more likely in women who are pregnant, have uncontrolled diabetes, or who use oral contraceptives. Candida often occurs after taking antibiotics which kill off the healthy bacteria, like lactobacilli, naturally found in the vagina, as this causes a bacterial imbalance, making it easier for candida to flourish.

Some women suffer repeated attacks of thrush, which is sometimes linked with low levels of iron. Iron is needed by white blood cells to make the chemicals used to destroy candida infection. If you suffer repeatedly, you should ask your doctor for a blood test to check your level of the iron protein, ferritin.

How is it diagnosed?
Diagnosing candida from symptoms and examination alone is not always accurate, as other conditions such as bacterial vaginosis cause similar problems and need different treatment. If you have genital symptoms, it is best to visit a genito-urinary medicine clinic (GUM clinic) for full screening and proper diagnosis.

Standard Treatment
A variety of anti-fungal treatments are available over the counter and on prescription. Some antifungal agents (for example, clotrimazole and miconazole) are used as creams or pessaries. Oral antifungal drugs (fluconazole and itraconazole) are also available for those who prefer swallowing a capsule rather than inserting a pessary.

Whatever treatment you use, it can take two or three days for symptoms to improve, as the soreness has to resolve after the yeast is eradicated. During this time, you will find it helpful to wash the area with a soothing acid-balanced treatment wash such as Lactacyd, which is available from pharmacies. Lactacyd wipes are helpful, too.

Avoid sex until all symptoms have gone. If you find sex keeps triggering thrush, see the tips on prevention. It may also help to wear a condom.

Alternative treatments
Some women find it helpful to smear the affected area with natural yoghurt containing a live bio culture of lactobacillus acidophilus. This bacteria colonises the vagina and may help to prevent overgrowth of candida. Bio yoghurt is particularly helpful if thrush is a result of antibiotic treatment. Taking a probiotic supplement to replenish intestinal levels of friendly digestive bacteria will help to suppress candida overgrowth in the gut ,which is believed to act as a reservoir for recurrent vaginal infections.

One of the most successful herbal remedies is Lapacho - also known as Pau d'Arco. Lapacho is an unusual Brazilian tree with carnivorous flowers that feed on insects, keeping the tree free from infection. Extracts from Lapacho bark can increase resistance to infection and are especially active against candida.

Other popular and effective options include grapefruit seed extract and olive leaf extracts. Siberian ginseng (eleutherococcus senticosus) is useful for boosting immunity when you are under excess stress.

Although there is no scientific evidence to support dietary changes, some women have found it helpful to follow a yeast-free diet. Others avoid alcohol, mushrooms, sugary foods, tea, coffee and chocolate. Eat a wholesome diet of salad, fruit, vegetables, pulses and wholegrain cereals instead.

Prevention

• Avoid getting hot and sweaty - use panty-liners and change them as necessary throughout the day, and avoid wearing tight underwear, especially nylon tights or tight trousers such as jeans. Stockings and cotton underwear are the best choices.
• Boil cotton underwear or hot-iron underwear gussets. This is because modern low-temperature washing machine cycles do not kill candida spores and you may re-infect yourself from your underclothes.
• Avoid using bath additives, vaginal deodorants or douches, which can upset the naturally acidic vaginal environment that helps to keep yeast and other infections at bay. The only ones to use are those specially formulated to soothe and treat soreness, such as the Lactacyd range.
• Eat an iron-rich diet and take a multivitamin and mineral supplement containing iron - a vitamin C source such as orange juice will also increase iron absorption in the gut.
• Consider asking your partner to use an anti-fungal cream as men can harbour yeast spores and pass infection back to you without developing symptoms themselves.
• Ask your doctor if you need a blood test to check for low iron levels or an underactive thyroid gland.

Dr Sarah Brewer is the author of Candida Albicans (Thorsons) which is available through libraries.

If you think you have thrush you can talk to others on the Your Health message board.