Hydrocolloid bandages are a type of wound dressing used in the treatment of mildly exuding wounds, such as minor burns or bed sores. They are made up of two layers, with an inner layer of gel-forming agents called hydrocolloid particles, which include carboxymethylcellulose, gelatin, and pectin. This inner layer promotes wound healing by absorbing exudate, which is a type of drainage made of water, white blood cells, and proteins. The outer layer forms a seal to protect the wound from bacterial contamination, foreign debris, urine, and feces, and also helps maintain a moist environment to promote healing. Hydrocolloid bandages are waterproof, flexible, and self-adhesive, and can be used for difficult-to-dress areas, such as the elbows, heels, or knees. They are meant to be used on open, superficial wounds and on oozing or opened pimples. Hydrocolloid bandages are not recommended for wounds with exposed bone or tendon or those with abundant drainage since they may be displaced.