Dhobi(e) itch or Jock itch (tinea cruris) is a common fungal infection that affects the skin of the inner thighs, buttocks and genitals. Jock itch causes an itchy, red, often ring-shaped rash in these warm, moist areas of your body and has also been called ‘ringworm of the groin’.
Jock itch is often caused by the same type of fungus that causes athlete's foot and sometimes ringworm of the scalp. In fact, the fungus that infects the groin area may be spread there from an athlete's foot infection. It is common in people who sweat a lot, like athletes. It also often occurs in people who are overweight, but anyone can get the infection.
How common is it?
The exact incidence of tinea cruris is difficult to determine. However, investigators in São Paulo, Brazil, discovered that 13.9% of dermatophytoses were tinea cruris.1 In another study of patients attending a dermatology clinic, testing for fungal skin infections revealed a total of 30.2% of the patients with athlete’s foot, 18.4% of patients with ringworm and 9.3% with jock itch.2
What causes it?
The dermatophyte T rubrum is the most common fungi for tinea cruris.
The germs that cause jock itch thrive in warm, humid environments. Such situations promote the washing away fungus-killing oils, making the skin more permeable and in turn making the skin more prone to infection. Jock itch often affects men who wear tight underwear or athletic supports. Jock itch may be contagious, being passed from one person to the next by direct skin-to-skin contact or contact with infected clothing. Jock itch usually stays around the creases in the upper thigh and does not involve the scrotum or penis. It is often less severe than other tinea infections, but may last a long time. Jock itch may spread to the anus, causing anal itching and discomfort. People who are obese or prone to heavy sweating are also at higher risk.
People with impaired immune systems or those with atopic dermatitis, a chronic, inherited skin disease characterized by itchy, inflamed skin, may be more susceptible.
What’s the outcome?
Jock itch usually responds promptly to treatment, but some cases last a long time.
Treatment3,4
Tinea cruris is best treated with antifungal drugs applied topically. If the skin inflammation causes discomfort and itching, glucocorticoid steroids may be combined with an anti-fungal drug to help prevent further irritation due to the patient scratching the area. Apart from the quicker relief of symptoms, this also helps minimise the risk of secondary bacterial infection caused by the scratching.
Prevention
- Shower or bathe daily and after exercising, participating in sports or sweating excessively. This helps keep the number of bacteria on skin in check. Wash hands often to avoid the spread of infection.
- Keep your groin area dry. Dry your genital area and inner thighs thoroughly with a clean towel after showering or exercising. Use powder around your groin area to prevent excess moisture.
- Change your underwear at least once a day or more often if you sweat a lot. Wash workout clothes frequently, ideally using a disinfecting laundry additive such as ERADICIL.
- Don't wear thick clothing for long periods of time in warm, humid weather.
- Make sure your clothes fit correctly, especially underwear, athletic supporters and sports uniforms. Avoid tight fitting clothes, which can rub and chafe your skin, making you more susceptible to jock itch. Try wearing boxer shorts rather than briefs.
- Do not share personal items. Do not let others use your clothing, towels or other personal items. Refrain from borrowing these items from others as well. Also make sure shared exercise machines are cleaned between uses.
- Treat athlete's foot to prevent its spread to the groin.
1 Silva-Tavares, H et al. Mycopathologia, Volume 149, Number 3, 1 March 2001 , pp. 147-149(3)
2 Welsh O, Welsh E, Ocampo-Candiani J, et al. Dermatophytoses in Monterrey, Mexico. Mycoses. 2006;49:119-123
3 Habif TP. Clinical Dermatology. 4th ed. St. Louis: Mo: Mosby; 2004
4 Rakel P. Textbook of Family Practice. 6th ed. Philadelphia, Pa: Saunders; 2002.