Trichomycosis Axillaris

Updated: Nov 08, 2021
Author: Nicholas V Nguyen, MD; Chief Editor: Dirk M Elston, MD 



Trichomycosis axillaris is a relatively common superficial corynebacterial colonization of the axillary hair shafts characterized by the presence of adherent granular concretions and a benign clinical course. When the pubic hair is affected, the condition is referred to as trichomycosis pubis.[1] Shelley and Shelley noted the coexistence of erythrasma, trichomycosis axillaris, and pitted keratolysis and termed it the corynebacterial triad.[2]


Corynebacteria are gram-positive rods and a major component of the cutaneous flora. A warm and moist local environment contributes to bacterial overgrowth. Hyperhidrosis and poor hygiene are risk factors for disease.


In 1952, Crissey et al identified Corynebacterium tenuis as the causative bacterium of trichomycosis axillaris[3] ; however, more recent reports suggest that the condition is caused by several species of the gram-positive diphtheroid Corynebacterium.[4, 5] It is not caused by a fungus, as the name may imply.



United States

No studies have assessed the frequency of trichomycosis axillaris in the United States.


In one study from the United Kingdom, trichomycosis axillaris was present in 27% of adult male students, and in the general population, 42% of male patients and 7% of female patients. Rho and Kim reported the corynebacterial triad in 13% of 842 Korean soldiers.[6]


No racial predilection is reported for trichomycosis axillaris.


Both sexes may be affected; however, trichomycosis axillaris appears to affect males more commonly, since most women shave their axillary hair.


Trichomycosis axillaris can affect any age group from puberty through adulthood.


Trichomycosis axillaris is a  benign infection of the hair with no associated mortality or complications. Once treated, it may recur if preventive measures (eg, shaving, antibacterial soap, antiperspirants) are not taken.

Patient Education

Instruct patients with trichomycosis axillaris to keep the area dry and clean. Shaving or trimming axillary hair usually is beneficial.




Trichomycosis axillaris typically is asymptomatic; however, patients may report malodorous sweat. Trichomycosis axillaris may be associated with similar findings of hair concretions in the pubic area (trichomycosis pubis).[7]

Physical Examination

Concretions encircle the hair shaft, making it appear beaded or thicker. Concretions are most common on the central portion of axillary hair.

Concretions consist of 1- to 2-mm red, black, or yellow nodules that adhere firmly to the hair shaft. The insoluble cement substance elaborated by the bacteria adheres to the hair shaft and, occasionally, invades and destroys cuticular and cortical keratin. The yellow color is observed most commonly (see the image below) and may stain clothes yellow. Black and red are seen most commonly in tropical climates.

Yellow concretions are seen over axillary hairs. Yellow concretions are seen over axillary hairs.

The hair shaft may become brittle and thus, more easily broken, but this is rare. Typically, since the hair shaft is not weakened, alopecia is not seen.

The underlying skin usually is normal, although hyperhidrosis of the affected regions is common.



Differential Diagnoses



Laboratory Studies

Potassium hydroxide preparation reveals bacteria within the concretions of trichomycosis axillaris. Perform bacterial culture as needed (typically not recommended).

Imaging Studies

Imaging studies are not needed for the diagnosis or follow-up of patients with trichomycosis axillaris.

Other Tests

Examination with a Wood lamp demonstrates a pale-yellow fluorescence. If erythrasma is also present, Wood lamp examination reveals coral-red fluorescence.

Histologic Findings

Corynebacterium is a gram-positive diphtheroid; it stains purple with Gram stain and appears as long, slender rods under the microscope.[8]



Medical Care

The fastest method of trichomycosis axillaris treatment is to shave the affected hair.

Benzoyl peroxide (gel or wash formulations) aids in treatment and prevents recurrence.

Antiperspirant helps treat and prevent trichomycosis axillaris by reducing axillary hyperhidrosis. Topical antibiotic preparations such as clindamycin or erythromycin also are effective.

"Drying" powders may assist treatment.


The following may help prevent trichomycosis axillaris:

  • Benzoyl peroxide (gel or wash) use

  • Antiperspirant use

  • Shaving axillary hair



Medication Summary

Treatment of trichomycosis axillaris can be achieved simply by shaving the affected hair. Application of a benzoyl peroxide gel or wash is effective and prevents recurrence. Antiperspirants also provide an effective means of therapy and prevention. Fusidic acid may be helpful in treating trichomycosis axillaris.

Topical skin products

Class Summary

Topical skin products are useful in the treatment of irritation caused by oxidized bacterial proteins in sebaceous follicles.

Benzoyl peroxide (Benzac, Benoxyl, Clearasil)

Free-radical oxygen is released upon administration and oxidizes bacterial proteins in sebaceous follicles, decreasing the number of anaerobic bacteria and irritating free fatty acids. Benzoyl peroxide is converted on the skin into benzoic acid, which has an antibacterial activity, as well as keratolytic and comedolytic effects. Benzoyl peroxide is available in 2.5%, 5%, and 10% gels, lotions, creams, or washes.


Class Summary

Antiperspirants interfere with normal secretions of sweat glands, drying the affected area. A variety of antiperspirants are available over the counter; prescription-strength topical desiccants listed.

Aluminum chloride hexahydrate (Drysol)

Aluminum chloride hexahydrate is an astringent agent used in the management of hyperhidrosis. It is a solution of 20% aluminum chloride in ethyl alcohol.

Topical antibiotics

Class Summary

Topical antibiotics work by inhibiting the growth of microorganisms that cause trichomycosis axillaris.

Clindamycin solution (Cleocin T)

Clindamycin solution is a lincosamide for the treatment of serious skin and soft tissue staphylococcal infections. It inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes causing RNA-dependent protein synthesis to arrest.

Upon application to the skin, drug is converted to the active component, which inhibits the microorganism. It is available as a topical solution, lotion, or gel for external use. The solution contains the equivalent of 10 mg/mL of clindamycin.

Erythromycin topical (T-Stat)

Erythromycin inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest. It is used for the treatment of staphylococcal and streptococcal infections. Topical erythromycin is available as a 2% topical solution.