[header] How to heal armpit rash [title] Wash the affected area with soap and water. [step] Place an ice pack or a damp towel against the armpit rash. You could also place a handful of ice cubes in a plastic bag and hold it against the rash. 
This will reduce the swelling and inflammation of the skin. [substeps] This technique is especially useful for heat rashes and rashes caused by lichen planus, an inflammatory skin condition.