The most common cause of pustules is acne, a skin condition that can clog skin pores with oil and dead skin cells. Pustules may also occur from an allergic reaction to food, environmental ...

3. Pustules Pustules contain fluid or pus, and they show up as large white bumps surrounded by red, inflamed skin. Most commonly, bacterial growth in clogged follicles causes pustules, McMahan says.

As suggested by its name, GPP typically presents as pus-filled blisters (i.e. pustules) on reddened skin, which can affect large areas of the body.