Strawberry legs

The most common cause is open comedones on the legs. The follicle holds a plug of keratin and sebum that darkens on contact with air, exactly as a blackhead does on the face. Shaving contributes twice over: it cuts the hair flush at the surface, leaving a dark stub visible inside a widened follicle, and it irritates the follicle so that it stays inflamed and pigmented.

Two other conditions share the nickname. Keratosis pilaris produces rough bumps rather than flat dots, and favours the thighs and upper arms. Folliculitis — follicles inflamed or infected, often after shaving or waxing — looks similar but is tender or itchy and may be pustular. Post-inflammatory hyperpigmentation from any of the above leaves dark marks after the bump itself has settled, and it is more visible and more persistent on deeper skin tones.

• Chemical exfoliation is the useful intervention: salicylic acid works inside the follicle, glycolic and lactic acid on the surface, and urea helps where the skin is rough as well as dotted.
• Scrubbing makes it worse, because it irritates follicles that are already inflamed.
• A sharp blade, a lubricating gel and shaving with the grain reduce the shaving contribution.

Expect weeks rather than days, and expect improvement rather than erasure — the follicles themselves are structural and do not disappear. Anything painful, spreading, pustular or unmoved by sensible care is worth showing a doctor rather than treating with another exfoliant, because folliculitis and other treatable conditions sit inside this same picture.