The interval between the first and second decoction of herbal medicine should be controlled at 30 minutes. At present, most hospitals advocate that Chinese medicine should be decocted for one and two times before taking, i.e. the first decoction is followed by adding water for the second decoction to decoct the herbal ingredients so as to increase the concentration of the drug and make the herbal medicine have better curative effects. Generally, the first decoction lasts 30 minutes to decoct various herbal ingredients, so the interval between two decoctions is 30 minutes. However, in fact, some herbal medicines can obtain all herbal ingredients in the first decoction, and the concentration of their drugs is not lower than that of the second decoction, which also has good efficacy for patients. In the second decoction of herbal medicine, you can add warm water to the decoction, and add half of the water of the first decoction. After 20 minutes, if there is still a lot of herbal soup, you can simmer it for a little longer, but if the amount is not much, you can stop simmering.