Jock itch

Disease Description (Causes and Symptoms)

• Definition: Tinea cruris is a non-abscess-forming superficial fungal infection caused by dermatophytes (mainly fungi of the Trichophyton genus) infecting the groin (inguinal region), where the skin folds and moisture accumulates easily.
• Cause/Pathophysiology: In the hot, humid, poorly ventilated inguinal region, fungi invade the stratum corneum, causing inflammation and scaling. It is commonly transmitted from athlete’s foot (tinea pedis).
• Main symptoms: Relatively well-demarcated erythematous (red) or yellowish-brown/brown scaly plaques (patches) may spread to the groin, inner thighs, around the scrotum, and buttocks, and itching (pruritus), burning, skin peeling, and fissures may occur. Long-lasting hyperpigmentation (dark patches or brown patches) may remain after treatment.
• Diagnosis: Confirmed by clinical findings + direct KOH examination (collecting scales and using KOH to identify fungal hyphae) or culture. A dermatology examination is recommended if necessary.

Treatment Methods

• Topical treatment (usual first-line choice)
  • Topical antifungals: azole agents (clotrimazole, miconazole, etc.), allylamine agents (terbinafine cream), and others. Generally used for 1–4 weeks; even after the clinical findings disappear, continued application for at least 1–2 additional weeks is recommended to prevent recurrence (in the cited material: an additional 2–3 weeks).
  • Directions for use: Apply generously 1–2 times a day, including the lesions and the surrounding normal skin.
• Systemic (oral) treatment (for extensive, recurrent, refractory cases or when the hands, feet, or nails are also affected)
  • Oral terbinafine (e.g., 250 mg once a day; the treatment period is 2–6 weeks depending on the extent of the lesions and response), or itraconazole (such as pulse therapy depending on the situation).
  • Oral medications may cause side effects such as hepatotoxicity, so monitoring such as liver function tests is necessary when indicated.
• Supportive and non-drug management
  • Keep the inguinal region dry: Wipe away sweat immediately, wear loose, well-ventilated cotton underwear, and avoid tight clothing.
  • Personal hygiene: Wash and dry towels, underwear, and sportswear at high temperatures, and use items that contact the skin separately. If athlete’s foot (tinea pedis) is present, treat it at the same time. Refrain from using public baths and saunas.
• Precautions (risk of complications and self-management)
  • Avoid topical steroid monotherapy: Using steroids alone may mask symptoms or spread the infection (“tinea incognito”). If used together with an antifungal, follow the doctor’s instructions.
  • The risk of recurrence is high (especially with untreated athlete’s foot, poor hygiene, obesity, diabetes, or immunosuppression).
  • Complications: Secondary bacterial infection, hyperpigmentation due to chronic disease, or skin thickening. In immunocompromised people, the disease may be more extensive or severe.
• Prognosis: It generally improves with appropriate treatment, but recurrence is common, and hyperpigmentation may remain for a long time.

Outpatient Visit Checklist (Items to Prepare and Examples of Questions to Ask the Doctor)

• Items to prepare (recommended to bring)
  • A list of medications currently being taken (including prescription drugs, OTC medications, and herbal medicines).
  • Information about any history of skin disease or allergies, and whether diabetes, liver disease, or immunosuppression is present.
  • A record of when symptoms started, aggravating factors (sweat, clothing, etc.), and previous treatments (medication name, duration, and effectiveness).
  • If possible, photographs of the lesions (from onset to the present), and photographs or a description of any athlete’s foot symptoms.
  • Bring any recent test results, such as liver function tests, if available.
• Items the doctor is likely to ask about during the outpatient visit (it is also helpful for the patient to make notes in advance)
  • When the symptoms began, the degree of itching, and aggravating factors.
  • Whether athlete’s foot, nail lesions, or similar symptoms are present in family members or people living together.
  • Medications previously used (topical/oral) and whether they were effective or caused side effects.
• Preparation for testing
  • If necessary, scales from the lesions may be collected for KOH examination or culture, so avoid applying extensive ointments or creams for a short period before the visit whenever possible (follow the doctor’s instructions).

Examples of General Questions to Ask the Doctor

• "Is topical treatment sufficient in this case, and what are the criteria for needing oral medication?"
• "What is the expected treatment duration for the prescribed medication, and what are its common side effects?"
• "What specific lifestyle changes should I make to reduce the risk of recurrence?"
• "Should athlete’s foot (tinea pedis) also be treated? Should family members or people living with me be examined or treated?"
• "Is it safe to use oral antifungals because of liver disease or other medications I am taking? Is monitoring necessary?"

Examples of Condition-Specific Questions (1–2)

• "My groin lesions have persisted for a long time or spread widely. How long should I wait before starting oral treatment?"
• "How long will the brown hyperpigmentation (discoloration) remaining after treatment last, and are there ways to improve it (such as laser treatment or topical medications)?"