Symptoms of Blisters
Blisters are characterized by pockets of fluid that form in the outer layers of skin after the skin has been rubbed or subjected to repeated friction / shear force. A blister is usually raised above the skin, but in cases of deeper blisters, it may penetrate downward and not appear above the skin. Most blisters are filled with clear fluid, but may be filled with blood if they occur in deeper layers of skin or if inflammation is present; they also may fill with pus if they become infected.
Depending on the cause, blistering may be accompanied by pain, redness, or itching.