You may get a butt rash from skin infections, allergic reactions, or a condition like eczema or psoriasis. To treat a rash on your butt, try gentle cleansers and avoid scrubbing or applying lotion.

A herpes rash usually appears as painful, fluid-filled blisters on the mouth or genitals. It can be mistaken for other conditions like shingles, scabies, or contact dermatitis. Antiviral medication ...