Excessive sweating in the armpits may be a normal physiological phenomenon, or it may be caused by hyperthyroidism, hyperhidrosis and other disease factors. 1. Normal physiological phenomenon: due to the armpit area is relatively hidden, and its subcutaneous distribution of a large number of sweat glands, sweating function is very strong, the patient in the physical labor, or hot days under the high temperature environment may appear armpit sweating, generally belong to the normal physiological phenomenon. 2. Hyperthyroidism: Hyperthyroidism is a kind of disease with increased excitability and hypermetabolism in the nervous, circulatory, digestive and other systems as the main manifestation of the disease, the patient may appear easy to be agitated, irritability and insomnia, fatigue, excessive sweating, emaciation, etc., therefore, excessive sweating in the armpits may also be caused by hyperthyroidism. 3. Hyperhidrosis: Hyperhidrosis refers to abnormal sweating of the local or generalized skin of the patient under normal living environment and conditions. Patients with hyperhidrosis may experience excessive sweating in the armpits. It is recommended that patients seek timely medical examination, clear causes for targeted treatment, pay attention to personal hygiene in life, diligent bathing, diligent change of clothing, to keep the armpit local skin clean and dry.