What is tinea cruris?
Tinea cruris, also known as groin ringworm or jockey itch, is an extremely common fungus infection. This ringworm belongs to a group of fungal skin infections called tinea, impinge or dermatophytosis, which are caused by fungi of the Trichophyton , Microsporum or Epidermophyton genera .
Dermatophytosis can affect several areas of the body, such as the scalp (tinea capitis), feet (tinea pedis) , beard (tinea barbae), nails (tinea unguium) or trunk and limbs (tinea corporis).
A fungal infection that affects the genital region, thigh, buttocks and groin is called tinea cruris. Groin ringworm is the second most common dermatophytosis, second only to tinea pedis, foot ringworm, popularly known as chilblain.
Tinea cruris is usually a mild, harmless infection, but it can spread quickly to the surrounding areas if it is in warm, humid places, as is often the case in the creases of the thighs and buttocks.
Tinea cruris is more common in men and adolescent boys and causes red, itchy skin lesions.
Causes of groin ringworm
The vast majority of cases of groin ringworm are caused by the fungus Trichophyton rubrum . This fungus can be a normal inhabitant of the skin, without necessarily causing disease, as our immune system can keep it under control, as long as the skin is kept clean and dry. In times of greater heat, however, some areas of the body are constantly moist and hot, such as the groin and genital region, favoring the proliferation of fungi, which results in mycoses.
The Trichophyton rubrum fungus , which causes jockey itch, is the same fungus that causes chilblains (athlete’s foot). Therefore, in many cases, the patient has dermatophytosis in the feet and groin at the same time.
How to catch tinea cruris
Tinea cruris is a contagious infection transmitted by fomites such as towels, sheets or clothing contaminated with the fungus.
Groin ringworm can also occur as self-contamination by ringworm of the feet (chilblain). After touching the feet, the patient may have their hands contaminated with the fungus, taking them to the groin area. Having sex with an infected person is also a form of contagion.
However, having contact with the fungus is not enough to develop ringworm. In order for the microorganism to defeat our immune system, it needs to find a suitable medium for its multiplication. Heat, humidity and absence of light are the most suitable conditions for the proliferation of fungi.
The groin is very prone to the occurrence of fungal infections, as, in addition to spending most of the day covered, it is a region of folds and hair that often remains moist and warm.
Hot times, wearing warm and tight clothes, excessive sweating, staying in wet bathing suits for a long time, poor personal hygiene and not changing underwear often are factors that favor the development of tina cruris.
Other risk factors for the appearance of groin ringworm are:
- Male sex (tinea cruris is three times more common in men).
- Hyperhidrosis .
- Practice intense contact sports such as wrestling.
- Obesity .
- Diabetes mellitus .
- HIV .
- Psoriasis .
- Atopic dermatitis .
Skin mycoses occur more frequently in people with weak immune systems, however, they are also very common in healthy individuals, without any health problems.
Symptoms of ringworm
The main symptoms of ringworm in the groin are itching and local redness, called a rash. The inflamed area may feel some burning, making it uncomfortable to wear certain types of underwear.
Tinea cruris usually starts with a reddish patch on the inside of one or both thighs, with sharp edges. When caused by the fungus Trichophyton rubrum , the disease usually spreads down over the thighs and even in the pubic region and buttocks. Lesions usually expand into circles.
In half of the cases the patient also has another type of tinea, usually tinea pedis (chicken).
In males, the scrotum and penis are usually spared. This is an important detail, as it helps to distinguish between tinea cruris and candida infection, as candidiasis in the groin in men often affects the scrotum.
The diagnosis can be confirmed by scraping the lesion and microscopically evaluating the material for fungi. As candida and dermatophytes are fungi with distinct features, it is possible to distinguish them through microscopic examination.
Treatment (best ointments)
The treatment of ringworm in the groin can be done with antifungal ointments, many of which are sold without a prescription.
The most suitable ointments for tinea cruris are those that contain one of the following antifungal agents:
- Terbinafine .
- Ketoconazole .
- Clotrimazole .
The last five substances have action against dermatophytes and candida. Creams or ointments based on nystatin are suitable for candidiasis, but not for dermatophytosis, and are not indicated for the treatment of tinea cruris.
You should avoid ointments that contain corticosteroids in their formula, such as betamethasone or triamcinolone, as these substances can interfere with the treatment and mask the symptoms.
In cases of immunosuppressed patients, or when treatment with ointments does not work, oral medications such as griseofulvin, fluconazole or terbinafine may be prescribed.
As tinea pedis (chicken) and onychomycosis (nail mycosis) are risk factors for tinea cruris, it is also important to treat both conditions to decrease the risk of recurrence of groin mycosis.
Daily application of talc to the groin to keep the area dry helps prevent recurrences.
Patients should be advised to avoid hot baths and tight clothing. Men should wear baggy underwear, preferably boxers (samba-canção underwear). Women should wear cotton panties and avoid tight pants.
After bathing, the inguinal area should be very dry. It is suggested to separate a towel to dry the infected area and another for the rest of the body. Do not wear the same underwear after showering.
- Dermatophyte (tinea) infections – UpToDate.
- Diagnosis and Management of Tinea Infections – American Family Physician.
- Topical antifungal treatments for tinea cruris and tinea corporis – The Cochrane database of systematic reviews.