Cold and Pain Iron can improve blood circulation, promote metabolism, dispel wind and cold, relieve tendons and blood to relieve swelling and pain and invigorate blood stasis. This medicine is used for rheumatic paralysis and pain in the back and legs. It is a topical medicine and cannot be taken orally. Cut open the outer bag, take out the bag, shake it several times so that the medicine is fully loosened and exposed to the air, feel the heat by hand, place it inside the fixed belt and cover the painful area, each bag is heated for not less than 15 hours, during heat production, if there are hard knots, you can use your hand to gently by rubbing it loose. Pregnant women and those with broken and damaged skin should not be used.