Ringworm in Groin - Symptoms, Causes and Treatment

Ringworm in the groin, called in medicine of tinea cruris, is one of the most common fungal infections of the skin. Tinea cruris usually reach the inguinal (groin), thigh and buttock regions, causing red plaques and intense itching.

Tinea cruris
Tinea cruris

What is tinea cruris?

The superficial mycoses of the skin are called dermatophytosis or tinea. Dermatophyte fungi, that is, that cause dermatophytoses, are those of the genera Trichophyton , Microsporum or Epidermophyton.

Dermatophytosis can affect various areas of the body, such as scalp (tinea capitis), feet (tinea pedis), beard (tinea barbae), nails (tinea unguium) or trunk and limbs (tinea corporis).

The fungal infection that affects the genital and inguinal region (groin) is called tinea cruris. Mycosis of the groin is the second most common dermatophytosis, losing only to the tinea pedis, mycosis of the feet, popularly known as chilblain.


The vast majority of cases of ringworm in the groin are caused by the fungus Trichophyton rubrum. This fungus can be a normal inhabitant of the skin without necessarily causing disease, since our immune system can keep it under control as long as the skin stays clean and dry. In warmer times, however, some areas of the body are constantly moist and hot, such as the groin and genital area, favoring the proliferation of fungi, resulting in mycosis.

The fungus Trichophyton rubrum, which causes mycosis of the groin, is the same that causes the feverishness (athlete's foot). Therefore, in many cases, the patient has dermatophytosis in the feet and groin at the same time.

How to handle tinea cruris?

Tinea cruris is a contagious infection transmitted by fomites, such as towels, sheets or clothes contaminated with the fungus. Mycosis in the groin may also occur as self-contamination by mycosis of the feet. The patient, after moving their feet, may have their hands contaminated with the fungus, leading them to the groin area. Having sex with an infected person is also a form of contagion.

However, it is not enough to have contact with the fungus to develop ringworm. For the microorganism to overcome our immune system, it must find a conducive means for its multiplication. Heat, humidity and lack of light are the most adequate conditions for the proliferation of mycoses. The groin is very conducive to the occurrence of fungal infections, since, besides spending a large part of the day covered, it is a region of folds and hairs, which remains frequently moist and warm.

Times of heat, use of warm and tight clothing, excessive sweating, staying in wet clothes for too long, poor personal hygiene and not frequently changing the underwear are factors that favor the development of the tub creams.

Other risk factors for onset of mycosis in the groin are:

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 rash. The inflamed area may present some burning, making the use of certain types of underwear uncomfortable.

Tinea cruris usually begins with a reddish plaque on the inside of one or both thighs, with well-demarcated edges. When caused by the fungus Trichophyton rubrum , the disease usually extends downward, over the thighs and even in the pubic region and glutes. The lesions usually expand in the form of circles.

In half of the cases, the patient also presents another type of tinea, usually tinea pedis (frieira).

In the male sex, the scrotum and penis are usually spared. This is an important detail as it helps in the distinction between tinea cruris and candidal infection, since candidiasis in the inguinal region in men often attacks the scrotal sac.

The diagnosis can be confirmed by scraping the lesion and microscopically evaluating the material in search of fungi. Because candida and dermatophytes are fungi with distinct aspects, it is possible to distinguish them through microscopic examination.


The treatment of mycosis in the groin can be done with antifungal ointments, many of them sold without prescription.

The indicated ointments are those containing one of the following antifungal agents:
  • Terbinafine
  • Naftifine
  • Ketoconazole
  • Miconazole
  • Tioconazole
  • Clotrimazole
  • Oxiconazole

The last five substances have action against dermatophytes and candida. Creams or ointments based on nystatin are used for candidiasis but not for dermatophytosis and are not indicated for the treatment of tinea cruris.

Ointments containing corticosteroids in your formula, such as betamethasone or triamcinolone, should be avoided as these substances may disrupt 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.

Because tinea pedis and onychomycosis (nail fungus) are risk factors for tinea cruris, it is also important to treat both conditions to decrease the risk of recurrence of mycosis in the groin.

Daily application of talc in the groin area to keep the area dry helps prevent recurrences. Patients should be advised to avoid hot baths and tight clothing. Men should wear wide underwear, preferably boxers (samba-song underwear). Women should wear cotton panties and avoid tight pants. After bathing, the inguinal area should be very dry. It is suggested to separate one towel to dry the infected area and another to the rest of the body. Do not wear the same underwear after bathing.

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