There are several causes of acidity in the body as follows: 1. The most common factor is infectious factor, whether bacterial infection, viral infection or fungal infection, which will stimulate the body to produce antigenic antibody immune complexes. The pathogenic microorganisms will release lysozyme, bradykinin and prostacyclin to the blood and tissues while producing immune complexes, and the above-mentioned substances will induce the body to produce clinical symptoms and performance of acidity and pain. 2, the body acidity and pain and endocrine and metabolic diseases, such as periodic hyponatremia and hypokalemia, hypomagnesemia, will appear the clinical symptoms and performance of the body acidity. 3, thyroid function The clinical symptoms of acidity will appear in those who have hyperthyroidism and hypothyroidism. 4. The clinical symptoms and performance of soreness and lack of energy will also appear in the early stages of heat stroke. 5. The clinical symptoms of acidity will also appear in those who have excessive lactic acid accumulation or diseases in which lactic acid cannot be metabolized from the body, such as excessive exercise or over-exercise leading to long-term accumulation of lactic acid in the body.