folliculitis

Last edited 03/2021 and last reviewed 03/2021

Folliculitis describes infection that originates within a single hair follicle, usually caused by a bacterial infection with Staphylococcus aureus.

Several types are recognised differentiated on the severity of the infection, the area affected or the cause. Infection may be stubborn and persist for months or years.

Folliculitis is inflammation of the hair follicle caused by infection, chemical stimulation, or physical injury

• bacterial folliculitis is prone to occur in areas of the skin subject to rubbing, occlusion, and sweating, such as the neck, face, axillae, and buttocks
  
  
• aetiology of folliculitis is diverse, including occlusion folliculitis resulting from blockages caused by exposure to topical products that block the opening of the hair follicle, leading to inflammation, and Malassezia folliculitis, which is caused by Malassezia furfur (also known as Pityrosporum ovale) and presents as itching red papules over the chest, shoulders, or back (1)
  
  
• infectious causes
  • bacteria
    • Staphylococcal folliculitis
      •   most common form of bacterial folliculitis
        
        
    • Hot tub folliculitis
      • can present as red spots and pustules on the trunk
      • due to an infection with Pseudomonas aeruginosa from improperly sanitised hot tubs or spas
      • caused by Pseudomonas aeruginosa contamination of undertreated water in saunas or whirlpools (2)
        
        
    • Gram negative folliculitis
      • rare pustular facial eruption, usually following antibiotic treatment of acne
      • gram-negative pathogens including Klebsiella, Enterobacter, and Proteus species may replace the gram-positive flora on facial skin, nasal mucous membranes, and neighbouring areas, causing gram-negative folliculitis and boils (3)

    Yeasts

    • Pityrosporum folliculitis
      • presents as an itchy acne-like rash on the back and chest of young adults
      • most commonly, it is caused by Pityrosporum ovale (also called Malassezia).

    Fungi

    • Tinea capitis or ringworm of the scalp is a fungal infection involving the hair follicles of the scalp
      • generally, it presents as scaling and hair loss, but may cause more severe inflammation or folliculitis in some people.

    Virus

    • Herpes simplex virus or cold sore virus
      • occasionally cancause folliculitis
      • most commonly it affects men who experience recurrent localised facial herpes simplex infections and shave with a razor.

    Parasites

    • Demodex folliculitis 
      • presentation similar to rosacea
      • caused by the hair follicle mite demodex
      • occurs on the faces of people whose immune system has been suppressed, usually with medication.

    Environmental folliculitis

    • Mechanical folliculitis
      •  caused by chronic frictional factors
      • occurs frequently in men or women who shave their faces or legs with a razor, particularly if they do so against the direction of the hairs
      • occasionally, it may also be associated with the wearing of tight pants or obesity.
    • Occlusion folliculitis
      •  caused by blockages of the follicles as a result of exposure to topical products such adhesives, oil, moisturisers, greases and ointments that cause swelling of the skin of the hair follicle opening
    • Chemical folliculitis
      • caused by exposure to certain topical products such as coal tars and the overuse of topical medications such as corticosteroids
        • particularly on the facial region, leading to swelling and obstruction of the follicular opening.

    Folliculitis due to skin diseases

    Other forms (1)

    • Buttock folliculitis
      • a common problem in both men and women
      • may be a form or localised acne
      • can be an acute condition with painful pustules requiring oral antibiotics
      • can also be chronic and require topical maintenance products to manage the condition.
    • Drug-induced folliculitis
      • presents as uniform red spots and pustules
      • more common in people prone to acne
      • occurs within two weeks of taking certain medications such as oral corticosteroids, androgenic hormones, epidermal growth factor receptor inhibitors, lithium and some other anticonvulsants
    • Pseudofolliculitis barbae
      • a type of chronic inflammation seen in the beard area of men who shave
      • mostly commonly affects men with darker skin types and tightly curled hair.
      • as the cut hair grows, the curliness leads to the sharp point digging into the skin causing a mechanical inflammation.
    • Irritant folliculitis
      • occurs on the lower legs of women who shave, wax, pluck or use electrolysis for hair removal.
    • Eosinophilic folliculitis
      • an itchy bumpy or pustular rash that most commonly affects the head and neck but other body sites may also be involved
      • unknown cause
      • in some cases may be related to immune suppression, either due to medications or medical conditions such as malignancy or HIV. Rarely, it occurs in infants

Reference:

1. Gunatheesan S. Folliculitis. www.dermcoll.edu.au/atoz/ folliculitis/ (accessed 10/3/2021).
2. Zacherle BJ et al.Hot tub folliculitis: a clinical syndrome. Western Journal of Medicine 1982;137(3):191-4.
3. Boni R et al.Treatment of gram-negative folliculitis in patients with acne. American Journal of Clinical Dermatology 2003;4(4):273-6.