It is necessary to cover the boiling Chinese medicine and not to leave a gap. If you do not cover the lid, the temperature will not come up and the temperature will be lost outwards with the lid of the pot. The best choice is to use a casserole because it is more breathable and the heat is more even, which is helpful for boiling Chinese medicine. If you use an aluminum or iron pot, the active ingredients may be diluted and the iron in the pot will also penetrate the Chinese medicine, which will more or less affect the Chinese medicine. Therefore, boiling Chinese medicine must be covered, and it is definitely recommended to use a casserole. If the conditions are not enough, you can also use a stainless steel pot to boil, or use an induction cooker, but you need to cover it.