What causes red stripe on arm?

A red stripe on the arm can be caused by several factors, including skin infections like cellulitis, allergic reactions, or inflammatory conditions such as dermatitis. It may also result from trauma or irritation to the skin. In some cases, it can indicate more serious conditions, such as vascular issues or deep tissue infections, requiring medical attention. If the stripe is accompanied by swelling, pain, or fever, it's important to consult a healthcare professional.