What is body odor? Body odor is any strong or unusual odor related to the body. The medical term is bromhidrosis. Occasional abnormal body odor may be a temporary effect of a metabolic change, such as fruity breath in diabetic ketoacidosis, but by far the most common cause of abnormal body odor is excessive perspiration or hyperhidrosis (overactive sweat glands). Sweating, or perspiring, is necessary to cool the body and is triggered by warm temperatures, exercise or physical exertion, or as a stress response to nervousness, fear, embarrassment or anger. Fluid from sweating in combination with skin bacteria produce the familiar odor recognized as body odor. The two types of hyperhidrosis include primary or focal hyperhidrosis, in which your hands, feet and armpits sweat excessively; and secondary hyperhidrosis, in which you may sweat all over your body or in one area besides your feet, hands or armpits. Secondary hyperhidrosis is caused by other conditions, such as anxiety disorders, cancers, diabetes, hyperthyroidism (overactive thyroid), lung disease, pheochromocytoma (tumor associated with hypertension), tuberculosis (serious infection affecting the lungs and other organs), or other infections. Hyperhidrosis and body odor are rarely emergency conditions. If your body odor is persistent or causes you concern, seek prompt medical care.