The interval between the first and second time to take the drug, according to the rules of taking the drug, the general drug instructions are written on the rules of taking the drug, if it is taken twice a day, the interval is about 12 hours, if it is taken three times a day, the interval is eight hours, so the interval time can not be determined, according to the requirements of the drug to choose. But generally most of the drugs in four hours after taking the drug concentration is basically very small, if the condition requires a second dose of drugs, so that the impact on the body is not large, but not all drugs can be taken according to this rule, to follow medical advice, according to the doctor’s recommendations to take drugs, only according to their own will may cause adverse reactions.