Folliculitis is due to inflammation of hair follicles and can therefore be found in any region of the body with hair. It is characterised by an erythematous papule, often with a pustule. It may be pruritic.
The most common cause of folliculitis is infection, most commonly bacterial. Risk factors include:
- Nasal staph aureus colonisation
- Occlusion of hair follicles
- Itching other skin disorders
- Long term antibiotics or corticosteroids
- Hot tubs/swimming pools
The most common bacterial pathogen is Staphylococcus aureus. Empirical treatment with topical antibiotics is therefore often used, although a mild folliculitis will often resolve spontaneously. A nasal antibiotic to eradicate nasal carriage can also be given.
‘Hot tub folliculitis’ is often due to Pseudomonas aeruginosa. It is often self-limiting and resolves withing 7 to 10 days with good skin hygiene and avoiding contaminated water.
Fungal causes are also relatively common, and can be treated with a topical or oral antifungal.
Less common are viral / parasitic causes and drug-induced folliculitis.