Everyone has more or less underarm sweating. Underarm sweating is not a direct reflection of health status, but if there is excessive underarm sweating, it may be related to the individual’s constitution and endocrine level. Excessive sweating can also be caused if the thyroid gland is overly hyperactive or if you suffer from hyperhidrosis, both primary and secondary hyperhidrosis. Underarm sweating is caused by a pair of sweat glands under the skin folds in the center of the armpit that sweat in the summer heat or after exercise. If the sweat glands are overly active, it can lead to excessive sweating and at the same time produce an unpleasant odor, which is known as fox odor. Usually, the sweat glands can be removed surgically by making a small incision in the middle of the armpit.