Primary (focal) hyperhidrosis, oftentimes starting around puberty, is excessive sweating which is not caused by another medical condition. Most commonly, the armpits (technically called the axillae), the hands, the feet, and the groin are involved. Occasionally, the face, back, and chest are also affected. The sweating is usually symmetric (ie. both sides equally affected) and rarely occurs while sleeping. Secondary hyperhidrosis is excessive sweating as a side effect of another medical condition, such as menopause, cancer, diabetes or taking some medications. It often occurs while sleeping.