Itchy armpits may be caused by stinky sweating, florid chaff rash, psoriasis and other diseases. 1. Odorant sweat disease: the occurrence of this disease is related to abnormal secretion function of parietal sweat glands, adherence of bacteria to the skin surface, high temperature, sweat gland secretion, etc. It often occurs in armpits, soles, areola, etc. If you don’t pay attention to the cleanliness of the affected area, then the manifestation of special itching of the armpits will occur. 2. Mottled chaff rash: this disease is caused by Malassezia infection, with heredity, excessive secretion of skin oil, high temperature and humid environment, improper use of immunosuppressants and other factors. Adolescent and adult patients are more likely to occur in the neck, chest, armpits and other places, so some of the more serious patients will appear in the armpits particularly itchy situation. 3. Psoriasis: the cause of the disease is not clear, research shows that it is the result of genetic and environmental factors, such as viral and bacterial infections, excessive pressure, obesity, smoking and so on. Common symptoms include itching, burning, pain, etc., which can be manifested as particularly itchy armpits. There are other causes of itchy armpits (e.g. hives, eczema), and it is recommended that patients with itchy armpits should go to the hospital to complete the relevant examinations and identify the specific causes.