Rashes and small blisters on your wrist after sweating while wearing a metal watch or bangles are commonly caused by contact dermatitis. This occurs when your skin reacts to certain metals, such as nickel, which are often present in jewellery and watch straps. Sweat can worsen the irritation by increasing contact between the metal and your skin. To prevent this, avoid wearing the jewellery or watch that triggers the rash, especially during hot weather or exercise. Keep your wrist clean and dry, avoid scratching, and choose nickel-free or hypoallergenic accessories. You can also place a barrier, such as a protective cover or a thin cloth, between your skin and the metal. If itching or inflammation occurs, a doctor may recommend a suitable soothing cream or a mild steroid cream for short-term use. Seek medical advice if the rash and blisters spread, become painful, or show signs of infection.