oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Synonyms: thrush, vulvovaginal candidiasis
This is a yeast infection of the lower female reproductive tract. Rarely, male partners can suffer candidal balanitis.
The infective organism is a fungus that reproduces by budding:
- 90% are due to Candida albicans.
- 5% are due to Candida glabrata.
Other fungal infections of the vagina are caused by Saccharomyces cerevisiae (brewer's yeast) and, rarely, Trichosporon spp.
Candida is a normal commensal organism in the vagina. Pathological infection usually follows a change in the local environment or a decrease in the host's susceptibility to infection.
However, recent research suggests that symptomatic candidiasis is due to an exaggerated immunological response to the presence of candida, rather than a failure of immune mechanisms.
Incidence and prevalence
- This is difficult to gauge as many women self-treat using over-the-counter (OTC) medication. A Swedish survey of OTC and prescribed antifungal preparations for vaginal candidiasis in the mid-1990s, showed about 85-90 cases per 1,000 women in the age group 15-45 years.
- Post-marketing surveillance of women prescribed quinolone and related antibiotics revealed an incidence of around 600 cases per 100,000 women. The control population (on antidepressants) had about 150 cases per 100,000.
- It is undoubtedly common and estimated to affect about 75% of women in their reproductive years. 10-20% of women have asymptomatic vaginal colonisation with Candida spp.
- Peak incidence age is 20-40 years.
- Diabetes mellitus (impaired glucose tolerance in pregnancy does not seem to be a statistically significant risk factor).
- Treatment with broad spectrum antibiotics (occurs in 28-33%).
- Vaginal foreign body.
- Contraceptives may predispose to recurrent vulvovaginal candidosis - but evidence is conflicting and of poor quality.
NB: the presence of foul-smelling or purulent discharge suggests bacterial infection.
- Erythema, possibly with fissuring
- Vulval oedema and erythema
- Satellite lesions
- Genital herpes simplex infection.
- Bacterial vaginosis (BV) plus vulvovaginitis infection with coliforms, Shigella spp., Group A streptococci.
- Trichomonas vaginalis.
- Sexually transmitted diseases (STDs).
- Atrophic vaginitis or hypo-oestrogenism.
- Helminthic infection (particularly threadworm/pinworm in young girls).
- Lichen sclerosus et atrophicus.
- Contact dermatitis (enquire about new hygiene products).
- Mechanical irritation, eg long-distance cyclists, sexual abuse in girls.
- Rectovesical fistula.
- Underlying immunosuppression/undiagnosed diabetes mellitus.
- Urinary tract infection.
- Routine culture is not required.
- In suspected bacterial/resistant or complicated infection, culture swabs from the anterior fornix or lateral vaginal wall.
- Refer to a genitourinary medicine (GUM) clinic if an STD is suspected.
- Take midstream specimen of urine (MSU) if symptoms could be due to urinary tract infection.
- Vaginal pH can be tested, but this is rarely used in practice and there is little evidence to support its use.
- pH 4.0-4.5 is normal and not altered by presence of candidiasis.
- pH >5.0 suggests bacterial vaginosis (BV) or trichomoniasis.
NB: cervical smears frequently reveal false-positive/asymptomatic candidal colonisation. This does not need further investigation unless there is a reason to suspect an underlying cause, or it is causing problems.
Routine recommendation of use of vulval moisturisers as soap substitute and regular skin conditioner (advice may need to be given to the patient that this does not constitute "internal use"). Also:
- Loose-fitting, natural fibre underwear
- Avoidance of topical irritants
- Good hygiene
Since all topical and oral azole therapies give a clinical and mycological cure rate of over 80% in uncomplicated acute vulvovaginal candidiasis, choice is a matter of personal preference, availability and affordability:
- Single episode:
- Topical azole, eg clotrimazole, miconazole. These are less expensive than their oral counterparts, but have some disadvantages.
- Oral triazole, eg fluconazole or itraconazole.
- Single high-dose oral triazole is effective as treatment for 3-7 days.
- Topical treatment may worsen burning symptoms in the first few days and the patient may prefer oral treatment if there is inflamed/oedematous vulva.
- Treatment failure:
- This may be due to poor compliance, and a further short course of treatment would then be suitable.
- Otherwise, use a longer course, perhaps combining oral and topical treatment. Where azole has failed, it may be due to infection by Candida glabrata and nystatin can be more effective.
- 10% of women have mixed infection with bacteria; there may the need to send vaginal swab for culture.
- Consider the possibility of an underlying disorder.
- Recurrent infections (4 or more episodes per year):
Send swabs for culture and exclude alternative diagnosis and underlying cause. Treatment consists of:
- An induction period of 1-2 weeks with at least one week of oral agent or 1-2 weeks of topical antifungal.
- This is followed by a maintenance period of 6 months with oral fluconazole 100 mg weekly or topical clotrimazole 500 mg weekly. NB: maintenance therapy with triazoles is unlicensed indication.
- Treatment can be stopped after 6 months and, if recurrent infection returns, then repeat induction/maintenance.
- Approximately 90% of women will remain disease-free at 6 months and 40% at 1 year.
- If infection occurs during the maintenance period, refer for specialist treatment, as it may be due to azole resistance.
- Non-albicans infection is harder to treat due to increased azole resistance. Nystatin, boric acid or flucytosine (usually under supervision of secondary care) may be used.
NB: there is no evidence to support the treatment of asymptomatic male sexual partners in either episodic or recurrent vulvovaginal candidiasis.
Treatment in pregnancy
Longer courses of topical clotrimazole, miconazole, econazole may be necessary. Nystatin is less effective.
Once a diagnosis of uncomplicated candidiasis has been made, women can be advised to treat further episodes with OTC products. However, advise seeking further medical opinion if:
- <16 or >60 years old.
- Pregnant or breast-feeding.
- Symptoms differing from normal, eg malodorous discharge, ulcers, blisters.
- Systemic upset.
- 2 episodes in 6 months and the patient has not seen their GP for 1 year.
- The patient/partner has had a previous STD.
- Abnormal menstrual bleeding/lower abdominal pain
- Previous adverse reaction to antifungal treatments, or they are ineffective.
- Symptoms persist >7 days.
- There is no evidence supporting oral or vaginal lactobacillus for the prevention of vulvovaginal candidiasis.
- There is also insufficient evidence to make any recommendations regarding carbohydrate or yeast intake.
- Zafirlukast 20 mg twice daily for 6 months may induce remission. Zafirlukast may be considered as maintenance prophylaxis for recurrent vulvovaginal candidiasis, particularly in women with a history of atopy. Cetirizine has also been shown to give remission from symptoms.
- Tea tree oil (and other essential oils) have been shown to be antifungal in vitro. However, they may cause hypersensitivity reactions and there is insufficient evidence to recommend their use.
Complications and prognosis
- Cure rate is 80% for uncomplicated cases.
- About 20% will have treatment failure (defined as persisting symptoms at 7-14 days).
- Recurrent candidiasis (defined as >4 episodes per year) can affect up to 50% of sufferers at a given period in their life.
- Depression and psychosexual problems can occur in women who suffer recurrent episodes.
- Treatment during pregnancy is more likely to fail.
Further reading & references
- Hedayati T et al; Candidiasis in Emergency Medicine, Medscape, Apr 2010
- World Health Organization; Treatment flowchart: vaginal discharge in pregnancy and postpartum period
- The management of women of reproductive age attending non-genitourinary medicine settings complaining of vaginal discharge, Faculty of Family Planning and Reproductive Health Care and British Association for Sexual Health and HIV (2006)
- Sobel JD; Vulvovaginal candidosis. Lancet. 2007 Jun 9;369(9577):1961-71.
- Fidel PL Jr; Immunity in vaginal candidiasis. Curr Opin Infect Dis. 2005 Apr;18(2):107
- Mardh PA, Wagstrom J, Landgren M, et al; Usage of antifungal drugs for therapy of genital Candida infections, purchased as over Infect Dis Obstet Gynecol. 2004 Jun;12(2):91
- Wilton L, Kollarova M, Heeley E, et al; Relative risk of vaginal candidiasis after use of antibiotics compared with antidepressants in women: postmarketing surveillance data in England. Drug Saf. 2003;26(8):589
- Mitchell H; Vaginal discharge - causes, diagnosis and treatment. BMJ 2004; 328: 1306-1308.
- Candida - female genital, Clinical Knowledge Summaries (2007)
- Kelekci S, Kelekci H, Cetin M, et al; Glucose tolerance in pregnant women with vaginal candidiasis. Ann Saudi Med. 2004 Sep
- Management of vulvovaginal candidiasis, British Association for Sexual Health and HIV (2007)
- Watson MC, Grimshaw JM, Bond CM, et al; Oral versus intra Cochrane Database Syst Rev. 2001;(4):CD002845.
- Donders GG, Prenen H, Verbeke G, et al; Impaired tolerance for glucose in women with recurrent vaginal candidiasis. Am J Obstet Gynecol. 2002 Oct;187(4):989
- Young GL, Jewell D; Topical treatment for vaginal candidiasis (thrush) in pregnancy. Cochrane Database Syst Rev. 2001;(4):CD000225.
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Dr Hayley Willacy
Dr Hayley Willacy
Prof Cathy Jackson