Medically reviewed by Susan Bard, MD Some causes of underarm rash include infection, allergic reaction, and inflammation.

The best heat rash treatment methods include ... to avoid blocking sweat glands and further irritating your rash. Steroid creams like hydrocortisone can be purchased over-the-counter at varying ...

To treat a poison oak rash, use a steroid cream, calamine lotion, or antihistamine. Poison oak is a shrub that grows on the US west coast and can cause an allergic skin reaction in about 85% of ...