Yellow card is used externally. Before use, the mustard packet (4 cells) is shaken to distribute the powder uniformly throughout the cells of the bag. Place the bag for 15-20 seconds in warm water, then apply to the skin with the porous side of the paper. Cover with a dry, dense tissue, tightly press against the body and leave for 2-3-5-10 minutes (until a persistent redness appears), depending on the age of the patient and the sensitivity of the skin. If you feel a strong burning sensation, you must loosen the mustard plaster to the body for a while or remove it.