There are several common reasons for excessive sweating in the armpits as follows: 1. congenitally rich sweat glands, there are abundant sweat glands under the armpits, which are responsible for secreting sweat. some people are born with abundant sweat glands, which can lead to excessive sweating in the armpits. 2. the physiological structure of the armpits causes the area to be easily moist and sweaty, especially in summer, in a hot, humid environment. 3. when wearing clothing that does not absorb sweat or dissipate heat, it may lead to aggravated sweating. 4. Sympathetic excitement, special stressful situations lead to sympathetic excitement, which in turn causes sweat secretion. 5, certain diseases, such as hyperthyroidism, hyperthyroidism is a disease characterized by high metabolism of the organism, the corresponding axillary sweat glands will also secrete more. 6, after eating hot drinks, overheated food, food heat effect caused.