An infection of the topmost layers of the skin, especially one caused by staphylococci, may produce pustules, which look like small blisters containing a thick, yellowish material.

Acne lesions frequently contain pus. This close-up photograph shows small acne pustules with surrounding inflammation (erythema).

The face is the most common location of acne. Here, there are 4 to 6 millimeter red (erythematous) pustules, some with bridging scars and fistulous tract formation (connecting passages). Severe acne may have a profound psychological impact and may cause scarring. Effective treatments are available for this type of acne.

Pus-filled lesions (pustules) are unusual in alopecia areata, but can occur, as in this picture. The pustules are infected where medication was injected into the area.

This is a close-up of a dermatitis reaction. It consists of a large, red (erythematous) lesion (plaque) with numerous small pus-filled areas (pustules).