Small bumps on the inside of the arm may be a sign of eczema or chronic dermatitis. Since it is difficult for external infections to occur in the inner arm, once these bumps appear, they may be due to allergic inflammatory reactions caused by poor sweating or prolonged lack of ventilation or air circulation. Usually, allergic inflammatory reactions in such places are usually in the form of papules or papules. So you see little bumps, either in flakes or in isolated form. After the appearance of these bumps, you can use anti-allergy medication for external application or take oral medication, usually oral medication such as epinastine or loratadine, etc. You can also use a little topical medication, such as Denide cream.