Chapped skin anywhere is not pleasant. It burns, itches and just plain hurts. Having it in an area that sweats can make it even worse, because the sweat gets into the tiny cracks caused by the chapping and causes the pain to intensify. Knowing what to do when you have chapped underarms can make it less unpleasant until your skin heals.
Know the Cause
To treat your chapped underarms, you need to know the cause. In most cases, it is sweat and friction. Since the underarm is a central location for many of the body's sweat glands, this area perspires heavily during exercise or stress, and this wetness can irritate your skin---especially if you shave. Added to this is friction, if you are running or using your arms a lot, resulting in a recipe for irritated, chapped painful skin. While this is the more common cause, chapped underarms can also come from extreme cold and dry air. If you are being exposed to dry cold air, your skin may dry out and "chap." While this is less likely on your underarm, it is possible.
Baby powder, or cornstarch, is a good treatment for chapped underarms. It dries the wetness and provides a barrier to the skin. It also allows the skin to "glide" back and forth rather than "rub." This eliminates friction which, in turn, eliminates irritation and chapping. A key to this treatment is to apply it several times a day. You will need to put powder on fresh from the shower, and then keep some with you during the day to apply it whenever you feel irritation beginning.
If your underarms are chapped from cold, dry air, or are rubbing during a repetitive action---such as running---then you might want to smear some Vaseline on the rubbing area before you begin the activity. The Vaseline softens the dry skin and keeps the friction from rubbing it raw. As with the powder, you will need to keep this product with you until your skin heals, because it will need reapplication after awhile.