Whether or not you need to retake the medicine after half an hour of vomiting depends on how quickly the medicine is absorbed. Slowly absorbed drugs need to be taken again, fast absorption generally do not need to eat again. 1. slow absorption of drugs: for taking the slow absorption of drugs, such as amiodarone hydrochloride, generally can not be fully absorbed by the patient’s body within half an hour, in the human body to play the effect of the drug, half an hour after taking the drug vomit may need to re-take the drug. 2. fast absorption of drugs: for the body can be quickly absorbed in the body of drugs, such as metoprolol, usually within half an hour. Patients taking fast-absorbing drugs half an hour vomiting also generally do not need to re-take. The medication should be used under the guidance of a doctor, not blindly self-medication, in order to avoid adverse effects.