Let’s start by looking at folliculitis on hair-bearing areas. Compared to areas of skin without obvious hair, this is both more common and an easier diagnosis to make.
Look for multiple bumps each centred on a hair follicle. The bumps contain inflamed material. When infected, you’ll see whitish material leading to the name “pustules.” You may see a hair come from the middle of the bump. Multiple pustules each centered on a hair follicle is very typical of bacterial folliculitis.
In non-hairy areas it may be harder to know if you’re looking at an inflamed hair follicle, or something else like an insect bite.
The deeper the inflammation, the more pronounced the appearance – as you’d expect. A boil is the deepest type of folliculitis whilst superficial folliculitis may appear very subtle as you can see in the photos.
Look at the distribution of the folliculitis. There are characteristic types of folliculitis that occur in certain parts of the body:
- Under the arms or in the groin. These hair-bearing areas are are subject to friction, heat and/or sweat.
- Legs that have been shaved (so-called pseudofolliculitis). Folliculitis may also be caused by trauma of hair follicles by waxing or hair-removal creams.
- Legs that have been covered in cream or ointment that may block the hair follicles.
- Trunk and/or buttocks – these are commonly non-infectious in younger to middle aged people. May be triggered by wearing occlusive clothes or working in a warm environment.
- Severe Scalp folliculitis may be caused by folliculitis decalvans.