It takes about 2-3 days to apply potato chips externally to reduce swelling. When the skin is traumatized or injected with swelling and fluid oozing out, you can take the method of applying potato chips externally to reduce swelling. Because the potato flakes themselves contain more starch, in a state of high osmotic pressure, which is conducive to the oozing of liquid from the hair vessels. In addition, potatoes contain natural alkaloids that can be adsorbed in the capillaries and have the effect of reducing swelling and relieving pain. However, it is only conducive to capillary fluid outflow, the specific swelling time and the situation of the injury and individual differences. If the injury is serious swelling and pain, or the patient’s physical condition is poor, it will take at least 5 days to reduce the swelling. For traumatic skin swelling, it is recommended to cut potatoes into slices and apply them externally to the wound. Use for about 2 days and observe the effect of swelling. If the effect is good can continue to compress, if the effect is poor, can be used hot towels on the wound, apply safflower oil, or other bruise medicine treatment.