Clotrimazole is an imidazole antifungal agent widely used for the treatment of thrush (candidiasis), particularly vaginal thrush and oral thrush, caused by Candida albicans and other Candida species. It works by disrupting fungal cell membrane synthesis, leading to cell death. In the UK and many other countries, it is commonly sold under the brand name Canesten®, available in various formulations tailored for vaginal, oral, and skin fungal infections.
Active Ingredient
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Clotrimazole: An imidazole derivative
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Potent fungistatic and fungicidal action depending on concentration and exposure time
Mechanism of Action
Clotrimazole works by inhibiting the enzyme 14-α-demethylase, a key step in the biosynthesis of ergosterol, which is essential for fungal cell membrane integrity.
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Disruption of ergosterol → increased membrane permeability
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Leakage of cellular contents → fungal cell death
It targets a broad range of yeasts, dermatophytes, and some gram-positive bacteria. In vaginal thrush, it targets Candida albicans, which colonizes the vagina and proliferates under hormonal or antibiotic influence.
Indications for Thrush
Clotrimazole (Canesten) is indicated for:
Vaginal Thrush (Vulvovaginal Candidiasis)
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Itching
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White, thick, curd-like discharge
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Redness or soreness
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Pain during urination or intercourse
Oral Thrush (Oropharyngeal Candidiasis)
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White plaques on tongue and inside of cheeks
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Redness, soreness
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Burning sensation
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Difficulty swallowing (in more severe cases)
Formulations for Vaginal Thrush
Canesten® offers multiple delivery forms of clotrimazole for intravaginal and external use:
Vaginal Tablets / Pessaries
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Clotrimazole 500 mg (single-dose treatment)
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Clotrimazole 200 mg (3-night course)
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Inserted deep into the vagina at night using an applicator
Vaginal Creams
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Clotrimazole 10% vaginal cream (single-dose)
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Clotrimazole 2% vaginal cream (used once daily for 3 days or longer)
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Used internally via an applicator
External Creams
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Clotrimazole 1% or 2% cream
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Applied to vulva and surrounding area to relieve itching, redness, soreness
Combination Packs
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Canesten Thrush Combi®
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Vaginal tablet + external cream
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Cream relieves external symptoms; tablet treats internal infection
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Dosage and Administration
Vaginal Thrush
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500 mg vaginal pessary: Single dose inserted at night
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200 mg pessary: One nightly for 3 consecutive nights
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2% cream: One full applicator (5 g) inserted once daily for 3 nights
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10% cream: Single applicator dose (5 g) for one night
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1% or 2% external cream: Applied 2–3 times daily to external vulval area until symptoms resolve
Full relief may take 2–3 days post-treatment. If symptoms persist beyond 7 days or recur frequently, a medical evaluation is advised.
Dosage for Oral Thrush
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Clotrimazole oral troches (lozenges) (available in some markets, e.g., U.S.):
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10 mg, dissolve one troche in the mouth 5 times daily for 14 days
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Note: In the UK, miconazole oral gel is more commonly used for oral candidiasis than clotrimazole.
Contraindications
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Hypersensitivity to clotrimazole or imidazole antifungals
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For vaginal products: Do not use during menstruation
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Avoid intravaginal use in children under 12 years unless prescribed
Precautions and Warnings
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Pregnancy:
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Vaginal creams/pessaries may be used during pregnancy, especially in the second and third trimester
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Use fingers instead of applicator to insert pessaries during pregnancy to avoid trauma
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Always consult a doctor before use
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Breastfeeding:
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Safe for external use
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Avoid application on or near the nipple during breastfeeding unless advised
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Contraceptives:
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Vaginal creams may reduce effectiveness of latex condoms or diaphragms
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Use alternative contraception for 5 days after use
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Recurrent Thrush:
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If symptoms recur more than 2–3 times in 6 months, reassess for underlying causes (e.g., diabetes, immunosuppression)
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Side Effects
Topical / Vaginal Use
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Mild burning, itching, redness
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Vaginal discomfort or pelvic cramps
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Irritation of penis in male partner (if present)
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Allergic reactions (rare):
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Rash
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Urticaria
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Anaphylaxis (very rare)
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Drug Interactions
Minimal due to topical or intravaginal use, but:
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May interfere with polyisoprene and latex condoms or diaphragms (reduced integrity)
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Oral clotrimazole may interact with:
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Tacrolimus
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Sirolimus
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Warfarin (increased INR, rare)
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Microbiological Considerations
Clotrimazole is fungistatic and fungicidal against:
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Candida albicans
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Candida glabrata (variable sensitivity)
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Candida tropicalis
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Some dermatophytes (Trichophyton, Microsporum, Epidermophyton)
Resistance is uncommon but may occur with prolonged or repeated use, particularly in non-albicans Candida species
Patient Counseling Points
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Wash hands before and after application
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Insert pessary or cream at night, lying down
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Do not use tampons during treatment
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Abstain from sexual intercourse during active infection and while using intravaginal treatments
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Consider partner treatment if recurrent infections occur
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Avoid tight clothing and maintain genital hygiene
When to See a Doctor
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First-time thrush infection
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Under 16 or over 60 years old
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Symptoms persist >7 days after treatment
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Recurrence within 2 months
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Symptoms such as fever, unusual bleeding, foul-smelling discharge, or abdominal pain
Storage
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Store at room temperature (15–25°C)
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Keep out of reach of children
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Protect from moisture and direct sunlight
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Do not freeze creams or pessaries
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