What causes blue or purple patches on the legs, and why don't they hurt?

Blue or purplish patches on the legs without pain may be caused by poor blood return, coagulation disorders, immune system dysfunction, or other reasons. It is recommended to seek medical attention at a hospital to determine the exact underlying cause of the symptoms.

1. Poor Blood Return

Wearing overly tight clothing, prolonged sitting with lack of physical activity, or unhealthy daily dietary habits may all affect normal blood circulation, leading to impaired venous return. This can result in bluish patches on the legs that are not painful.

2. Coagulation Disorders

Coagulation disorders are usually caused by abnormalities in the body's clotting mechanism or deficiencies in clotting factors. If such conditions lead to reduced platelet counts, they may cause local blood vessel rupture and blood leakage, resulting in painless bluish patches on the legs.

3. Immune System Dysfunction

Long-term excessive alcohol consumption, severe physical exhaustion, or exposure to allergens may trigger immune system dysregulation. This imbalance may lead to either overactive immune responses or weakened defense mechanisms, increasing capillary permeability and causing blood leakage, which manifests as painless bluish patches on the legs.