A rash in your armpit, or "axilla," can be mild or severe, short-lived or chronic, and treatments depend on the underlying cause. In this video, find out 5 reasons why your armpit can breakout in a rash and how to treat and avoid breaking out in the future. Over-the-counter creams can work best for some rashes, while others require a prescription. Any time you have lingering symptoms, it's not a bad idea to see a healthcare provider who specializes in skin conditions.