... 5 minutes.--Cold usage: Lay the gel pack flat in freezer for at least two hours.--hot compress: alleviate ... , sciatica, vertebral pain, improve mucous membrane scar after surgery--cold compress: physical therapy for traumatic hemorrhage, heatstroke, itch, headache, strain ... , scald and fatigue--Medical available for hot or cold compress easily and conveniently, necessary as a first-aid for ...