Red and purple patches on the inner thighs may be caused by swelling lines, subcutaneous bleeding spots, or even infections, etc. It is recommended to go to a regular hospital and consult a professional in time. 1. Expansion lines: caused by the loss of elasticity and breakage of the dermis layer of the skin during puberty or sudden and rapid weight gain, which generally do not require special treatment. 2. Subcutaneous bleeding spots: consider external friction or excessive pressure caused by subcutaneous vasodilatation, hot compresses to promote absorption and dissipation. 3. Infection: ringworm or eczema and other infectious diseases, the affected area may appear red or purple plaque, may also be associated with itching, it is recommended to consult a professional to deal with. In general, the occurrence of unexplained red and purple patches on the inner thighs, it is still recommended to go to a regular hospital to check to avoid delays.