Tinea cruris — commonly known as jock itch — is a dermatophyte fungal infection of the groin, inner thighs, and sometimes the buttocks. It is one of the most common fungal skin infections presenting at the pharmacy counter, particularly in warm weather, and is straightforward to treat with over-the-counter antifungals when identified correctly.

Who gets it and why

Tinea cruris is caused by the same dermatophyte fungi responsible for athlete's foot (Trichophyton rubrum, Trichophyton interdigitale, Epidermophyton floccosum). It thrives in warm, moist skin folds and is more common in:

• Men (the condition is less common in women, partly because of anatomical differences in groin fold apposition)
• Physically active individuals who sweat heavily
• People who wear tight, non-breathable clothing
• Patients with concurrent athlete's foot — auto-inoculation from feet to groin via towels or hands is the most common transmission route
• Overweight or obese individuals, where increased skin fold moisture creates a favourable environment
• Immunocompromised patients (diabetes, HIV, long-term steroid use)

The link with athlete's foot is particularly important for pharmacy counselling. According to NICE CKS, up to one-third of patients with tinea cruris have concurrent tinea pedis. If the foot infection is not treated, the groin infection is likely to recur.

What it looks like

The typical presentation is a well-defined, erythematous (red), scaly rash with a raised, active border that spreads outwards from the groin crease. Key features:

• Location: inner thighs and groin folds, often bilateral. May extend to the buttocks but typically spares the scrotum (this helps distinguish it from candidal intertrigo, which often involves scrotal skin).
• Border: raised, scaly, and advancing — the classic "ringworm" edge.
• Central clearing: the centre of the rash may appear less inflamed than the border as it spreads outward.
• Itch: prominent, often worse after exercise or sweating.

Pharmacy treatment

First-line: topical antifungal

For uncomplicated tinea cruris, NICE CKS recommends a topical antifungal as first-line treatment. All of the following are effective and available OTC:

Terbinafine cream offers the advantage of a shorter treatment duration (typically 1–2 weeks versus 2–4 weeks for azoles) because it is fungicidal rather than fungistatic.

Application advice

Correct application technique improves outcomes:

1. Wash and thoroughly dry the affected area before applying
2. Apply a thin layer extending at least 2cm beyond the visible edge of the rash
3. Continue treatment for at least one week after the rash has visibly cleared — premature stopping is the most common cause of recurrence
4. Wash hands after application to prevent spreading the infection

What NOT to use

• Hydrocortisone cream alone. A topical steroid will reduce itch and redness but allows the fungus to spread (tinea incognito). Combination products containing both an antifungal and a mild steroid (e.g. miconazole/hydrocortisone) can be useful for the first few days to manage severe itch, but the steroid should not be continued beyond 7 days.
• Antifungal powders alone. These may help prevent recurrence but are generally insufficient to clear an established infection.

Preventing recurrence

Prevention is as important as treatment, particularly for patients with recurrent episodes:

• Treat concurrent athlete's foot. This is the single most important preventive measure.
• Dry thoroughly after bathing. Use a separate towel for the groin and feet to prevent cross-contamination.
• Wear loose, breathable underwear. Cotton or moisture-wicking synthetic fabrics. Avoid tight jeans or synthetic underwear that traps moisture.
• Change underwear and workout clothing after sweating. Do not sit in damp gym clothes.
• Antifungal powder prophylaxis. For patients with frequent recurrence, applying an antifungal dusting powder (e.g. clotrimazole powder) to the groin area daily may help, particularly during summer months.
• Weight management. For overweight patients, reducing skin fold apposition reduces the warm, moist environment that fungi need.

When to refer

Most tinea cruris responds well to OTC treatment. Refer to a GP when:

• The rash does not respond to 2–4 weeks of appropriate topical antifungal treatment
• The infection is widespread (extending to buttocks, abdomen, or beyond)
• Scrotal involvement is prominent — this may indicate candidal infection rather than dermatophyte, and may need different treatment
• The patient is immunocompromised or diabetic and the infection is severe
• There is diagnostic uncertainty (differential includes candidal intertrigo, erythrasma, psoriasis, and contact dermatitis)

The pharmacy counter conversation

Patients may be embarrassed to discuss groin symptoms. A discreet, matter-of-fact approach works best:

"This is very common — it is the same fungal infection as athlete's foot, just in a different area. This antifungal cream will clear it up in a couple of weeks. Make sure you also check your feet, because if you have athlete's foot as well, you will need to treat both to stop it coming back."

PharmSee's pharmacy finder helps patients locate their nearest community pharmacy for skin consultations, and salary data is available for pharmacists exploring dermatology-related roles.

Key points

• Tinea cruris is a dermatophyte groin infection treatable with OTC antifungal cream
• One-third of patients have concurrent athlete's foot — treat both to prevent recurrence
• Terbinafine cream offers the shortest treatment course (1–2 weeks)
• Do not use hydrocortisone alone on a suspected fungal rash
• Refer if the rash does not respond to 2–4 weeks of treatment, involves the scrotum prominently, or is diagnostically uncertain

Sources: NICE CKS (Fungal skin infection — body and groin), BNF (Antifungals, topical), NHS (Ringworm). Article reflects guidance current as of April 2026.