Hydrocolloid bandages absorb wound fluid and form a whitish, gel-like or slightly raised area under the patch. That pale, swollen-looking bubble indicates the dressing is drawing out fluid and creating a moist environment that supports healing.
Wear time varies by type: many fabric bandages advertise about 24 hours, hydrocolloid or hydrogel dressings are intended for multiday protection (some products state up to five days), and some transparent film dressings may be worn for up to a week.
Look for waterproof seals, strong self‑adhesive backing, flexible/stretch materials that move with the body, and designs with four-sided seals or reinforced edges—these features improve hold during activity and in water.