What causes butt acne and pimples

Butt acne and pimples are actually called folliculitis, which is the name given to a group of skin conditions in which there are inflamed hair follicles ¹. The result is a tender red spot, often with a surface pustule.

Folliculitis may be superficial or deep. It can affect anywhere there are hairs, including chest, back, buttocks, arms and legs. Acne and its variants are also types of folliculitis.

Butt acne and pimples (folliculitis) can be due to infection, occlusion (blockage), chemical irritation and various skin diseases ². Bacterial folliculitis is the most common form of folliculitis.

Folliculitis affecting the buttocks is quite common and is often nonspecific, i.e. no specific cause is found. Butt acne and pimples (buttock folliculitis) is equally common in males and females.

• Acute buttock folliculitis is usually bacterial in origin (like boils), resulting in red painful papules and pustules. It clears with antibiotics.

• Chronic buttock folliculitis does not often cause significant symptoms but it can be very persistent. Although antiseptics, topical acne treatments, peeling agents such as alphahydroxy acids, long courses of oral antibiotics and isotretinoin can help buttock folliculitis, they are not always effective. Hair removal might be worth trying if the affected area is hairy. As regrowth of hair can make it worse, permanent hair reduction by laser or intense pulsed light (IPL) is best.

What causes bacterial folliculitis – butt acne and pimples ?

Bacterial folliculitis is usually due to Staphylocoocus aureus. Less often, coagulase-negative staphylococci and gram-negative organisms are responsible including anaerobes. Spa pool folliculitis is caused by pseudomonas.

Who gets bacterial folliculitis – butt acne and pimples ?

Bacterial folliculitis affects children and adults, with adolescents and young adult males most often infected. It is prevalent worldwide.

The following factors predispose to bacterial folliculitis:

• Maceration and occlusion (clothing, dressings, ointments)
• Frequent shaving, waxing or other forms of d/epilation
• Friction from tight clothing
• Atopic dermatitis
• Acne or other follicular skin disorder
• Use of topical corticosteroids
• Previous long-term use of antibiotics
• Anemia, obesity, diabetes, HIV/AIDS, hepatitis, cancer and other chronic illness
• Bathing in an inadequately cleansed hot tub or pool

What are the clinical features of bacterial folliculitis – butt acne and pimples ?

Bacterial folliculitis may be superficial or involve the whole hair follicle (a boil). It may arise on any body site, but is most often diagnosed in scalp, beard area, axilla, buttocks and extremities. Systemic symptoms are uncommon. Different types of bacterial folliculitis are described below.

Superficial folliculitis

Superficial staphylococcal folliculitis presents with one or more follicular pustules. They may be itchy or mildly sore. Superficial folliculitis heals without scarring.

A hordeolum or stye is bacterial folliculitis affecting an eyelash.

Furunculosis / boils

Furunculosis or boils presents as one or more painful, hot, firm or fluctuant, red nodules or walled-off abscesses (collections of pus). A carbuncle is the name used when a focus of infection involves several follicles and has multiple draining sinuses. Recovery leaves a scar.

Gram-negative folliculitis

Gram negative folliculitis develops in individuals using long term antibiotics for acne. The infection with gram negative organisms causes pustules in acne sites of the face, neck and upper trunk.

Hot tub folliculitis

Hot tub or spa pool folliculitis presents with painful papules and pustules on the trunk some hours after soaking in hot water, mainly in sites that were covered by bathing costume. It may be accompanied by mild systemic symptoms including fever. Untreated, it settles within about 10 days without scarring.

Complications of bacterial folliculitis – butt acne and pimples

Soft tissue infection

Bacterial folliculitis can lead to cellulitis and lymphangiitis; subsequent bacteraemia might result in osteomyelitis, septic arthritis or pneumonia.

How is bacterial folliculitis diagnosed ?

Bacterial folliculitis is usually diagnosed clinically but can be confirmed by bacterial swabs sent for microscopy, culture and sensitivity.

Blood count may reveal neutrophil leucocytosis when folliculitis is widespread.

Skin biopsy is rarely necessary. Histology shows dense neutrophilic infiltrate in subcutaneous tissue and foreign body reaction around a hair shaft.

How can folliculitis be prevented ?

• Keep skin clean and if dry, well moisturized.
• Minimise shaving and waxing. When shaving, use new blade each time and moisturise the skin afterwards.
• Do not wear tight fitting clothes.
• Ensure adequate sterilization of hot tubs.
• In case of repeated episodes of staphylococcal folliculitis, apply mupirocin ointment to the nostrils to eliminate S aureus carrier state.

What is the treatment for bacterial folliculitis – butt acne and pimples ?

• Warm compresses to relieve itch and pain
• Analgesics and anti-inflammatories to relieve pain.
• Antiseptic cleansers (eg hydrogen peroxide, chlorhexidine, triclosan)
• Incision and drainage of fluctuant lesions and abscesses
• Topical antibiotics such as erythromycin, clindamycin, mupirocin and fusidic acid. To reduce bacterial resistance, these should be applied for courses of no more than one week
• Oral or intravenous antibiotics for more extensive or severe infections
• Photodynamic therapy
• Repeated laser hair removal

Butt acne and pimples (folliculitis) due to infection

To determine if your butt acne and pimples is due to an infection, swabs should be taken from the pustules for cytology and culture in the laboratory.

Bacteria

Bacterial folliculitis is commonly due to Staphylococcus aureus. If the infection involves the deep part of the follicle, it results in a painful boil. Recommended treatment includes careful hygiene, antiseptic cleanser or cream, antibiotic ointment, and/or oral antibiotics.

Spa pool folliculitis is due to infection with Pseudomonas aeruginosa, which thrives in inadequately chlorinated warm water. Gram negative folliculitis is a pustular facial eruption also due to infection with Pseudomonas aeruginosa or other similar organisms. When it appears, it usually follows tetracycline treatment of acne, but is quite rare.

Yeasts

The most common yeast to cause a folliculitis is Pityrosporum ovale, also known as Malassezia. Malassezia folliculitis (Pityrosporum folliculitis) is an itchy acne-like condition usually affecting the upper trunk of a young adult. Treatment includes avoiding moisturisers, stopping any antibiotics and topical antifungal or oral antifungal medication for several weeks.

Candida albicans can also provoke a folliculitis in skin folds (intertrigo) or in the beard area. It is treated with topical or oral antifungal agents.

Fungi

Ringworm of the scalp (tinea capitis) usually results in scaling and hair loss, but sometimes results in folliculitis. In New Zealand, cat ringworm (Microsporum canis) is the commonest organism causing scalp fungal infection. Other fungi such as Trichophyton tonsurans are increasingly reported. Treatment is with oral antifungal agents for several months.

Viral infections

Folliculitis may caused by herpes simplex virus. This tends to be tender, and resolves without treatment in around 10 days. Severe recurrent attacks may be treated with aciclovir and other antiviral agents.

Herpes zoster (the cause of shingles) may also present as folliculitis with painful pustules and crusted spots within a dermatome (an area of skin supplied by a single nerve). It is treated with hihg-dose aciclovir.

Molluscum contagiosum, common in young children, may also cause follicular umbilicated papules, usually clustered in and around a body fold. Molluscum may provoke dermatitis.

Parasitic infection

Folliculitis on the face or scalp of older or immunosuppressed adults may be due to colonisation by hair follicle mites (demodex). This is known as demodicosis.

The human infestation, scabies, often provokes folliculitis, as well as non-follicular papules, vesicles and pustules.

Folliculitis due to irritation from regrowing hairs

Folliculitis may arise as hairs regrow after shaving, waxing, electrolysis or plucking. Swabs taken from the pustules are sterile ie there is no growth of bacteria or other organisms. In the beard area irritant folliculitis is known as pseudofolliculitis barbae.

Irritant folliculitis is also common on the lower legs of women (shaving rash). It is frequently very itchy. Treatment is by stopping hair removal, and not beginning again for about three months after the folliculitis has settled. To prevent reoccurring irritant folliculitis, use a gentle hair removal method, such as a lady’s electric razor. Avoid soap and apply plenty of shaving gel, if using a blade shaver.

Folliculitis due to contact reactions

Occlusion

Paraffin-based ointments, moisturisers, and adhesive plasters may all result in a sterile folliculitis. If a moisturiser is needed, choose an oil-free product, as it is less likely to cause occlusion.

Chemicals

Coal tar, cutting oils and other chemicals may cause an irritant folliculitis. Avoid contact with the causative product.

Topical steroids

Overuse of topical steroids may produce a folliculitis. Perioral dermatitis is a facial folliculitis provoked by moisturisers and topical steroids. Perioral dermatitis is treated with tetracycline antibiotics for six weeks or so.

Folliculitis due to immunosuppression

Eosinophilic folliculitis is a specific type of folliculitis that may arise in some immune suppressed individuals such as those infected by human immunodeficiency virus (HIV) or those who have cancer.

Folliculitis due to drugs

Folliculitis may be due to drugs, particularly corticosteroids (steroid acne), androgens (male hormones), ACTH, lithium, isoniazid (INH), phenytoin and B-complex vitamins. Protein kinase inhibitors (epidermal growth factor receptor inhibitors) and targeted therapy for metastatic melanoma (vemurafenib, dabrafenib) nearly always result in folliculitis.

Folliculitis due to inflammatory skin diseases

Certain uncommon inflammatory skin diseases may cause permanent hair loss and scarring because of deep seated sterile folliculitis. These include:

• Lichen planus
• Discoid lupus erythematosus
• Folliculitis decalvans
• Folliculitis keloidalis

Treatment depends on the underlying condition and its severity. A skin biopsy is often necessary to establish the diagnosis.

Acne variants

Acne and acne-like or acneform disorders are also forms of folliculitis. These include:

• Acne vulgaris
• Nodulocystic acne
• Rosacea
• Scalp folliculitis
• Chloracne

The follicular occlusion syndrome refers to:

• Hidradenitis suppurativa (acne inversa)
• Acne conglobata (a severe form of nodulocystic acne)
• Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens)
• Pilonidal sinus.

Treatment of the acne variants may include topical therapy as well as long courses of tetracycline antibiotics, isotretinoin (vitamin-A derivative) and in women, antiandrogenic therapy.

1. Folliculitis. https://www.dermnetnz.org/topics/folliculitis/[↩]
2. Durdu M, Ilkit M. First step in the differential diagnosis of folliculitis: cytology. Crit Rev Microbiol. 2013 Feb;39(1):9-25. doi: 10.3109/1040841X.2012.682051. Epub 2012 May 29. Review. https://www.ncbi.nlm.nih.gov/pubmed/22639852[↩]