Jock itch (Tinea cruris)

Definition

Jock itch is a fungal infection of the skin. It is also commonly known as dhobi’s itch or ringworm of the groin but the correct medical term is tinea cruris. This type of fungal infection typically occurs in the skin folds of the groin, upper thighs, perineum and buttocks. Although it affects both sexes, it is found more often in males.

Origin of names

The term jock itch arose as the condition was more frequently seen in athletes who wear jock straps. Dhobi’s itch is an Indian term for tinea cruris as this condition was more frequently seen in washermen (dhobis).

Symptoms

Tinea cruris appears as a reddish-brown, ring-shaped rash in the folds of the groin. The ring-shape of the rash also gives it its common name, ringworm infection. The edges of the ring-shaped rash are prominent and can be scaly or bumpy. There is severe itching in the region of the rash, which could also be painful. The rash does not usually extend to the genitals

The itching sensation and the rash could worsen due to the friction when walking or exercising. The lesions caused by tinea cruris may also get infected by other fungi and bacteria, further worsening the symptoms. Tinea cruris is also commonly associated with a similar infection in the feet (tinea pedis or athlete’s foot). In fact, the fungal infection from the feet could spread to the groin region due to scratching the feet with the hands and then touching or scratching the groin region.

Causes

Tinea cruris is caused by a group of fungi known as dermatophytes. Dermatophytes live on the skin and feed on the skin protein, keratin. Usually, the growth of dermatophytes on the skin is kept in check. However, the moist skin environment that results from warm weather, heavy sweating, and tight clothing stimulates the growth of dermatophytes.

In addition to moisture, the friction associated with the rubbing of skin folds (chaffing in the groin area) also increases the risk of acquiring tinea cruris. This is the reason why obese people who are more likely to experience chaffing are therefore prone to developing this fungal infection. Similarly, males are at higher risk because the scrotum lies in close contact with the skin of the thigh.

Tinea cruris is a contagious infection and can be spread through bathroom towels, bedsheets and sexual contact. The causative dermatophytes associated with tinea cruris are Trichophyton rubrum, Epidermophyton floccosum, Trichophyton mentagrophytes, and Trichophyton verrucosum.

Treatment

Tinea cruris is curable and not serious. It can be quickly and effectively treated with antifungals applied to the skin (topical) or ingested (oral).

Topical anti-fungal powders, creams or lotions (e.g., miconizole, clotrimazole, ketoconazole, terbinafine, econazole, ciclopirox, naftifine) should be applied to the affected area. These powders, creams and lotions are available over-the-counter and do not require a doctor’s prescription. However, a doctor should always be consulted in case the infection persists. Severe, persistent or recurrent cases may need to be treated with oral antifungals. A 4 to 6 week course of these drugs will usually be sufficient to eradicate the infection. Preventative measures need to be instituted thereafter.

Prevention

Since moisture is the main cause of tinea cruris infection and therefore the affected areas of the groin should be kept clean and dry. The affected areas should be washed with soap and water and then patted (not rubbed) dry using clean and dry towels. Sweaty clothes must be changed immediately.

Clothes and towels of an infected person should be washed separately to prevent the spread of infection to unaffected people. Tinea cruris infection has a tendency to reoccur in people who are susceptible to it. Therefore, preventive measures such as keeping the groin and foot areas clean and dry must be maintained even after successful treatment.

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