Irritant contact dermatitis is a reaction caused by direct physical or chemical injury to the epidermis. The damage caused by an irritant leads to inflammation, manifested in the skin as erythema, edema, and scaling. Irritant contact dermatitis should be differentiated from true allergic contact dermatitis, which is a delayed type-IV hypersensitivity (immune) reaction.

Contact dermatitis of the penis is more often of the irritant type rather than allergic due to the persistent moisture and maceration in the genital region. Most males are susceptible to irritant dermatitis.

Soaps, detergents, antiseptic solutions, and topical medications are often the source of irritation. Prolonged or recurrent exposure to an irritant often causes the skin to become lichenified, hyperkeratotic, and inflamed.

Early in the course of irritant contact dermatitis, patients typically present complaining of a burning or stinging; the symptoms and skin eruption usually follow the exposure by hours if the irritant is strong (whereas in allergic contact dermatitis, symptoms are usually delayed by approximately 2 days following exposure). As the irritation becomes chronic and the skin continually inflamed, pruritus can become a predominant symptom.