A doctor may want to give a medicine, but something about the patient’s body says do not give that. That something contraindicates the medicine: it is a medical reason not to use that particular drug or treatment. In real hospital talk you will hear this most often as an adjective: the drug is contraindicated in pregnancy, or contraindicated with another medicine the person already takes. It is a formal medical word. Ordinary people usually say “you should not take this if…” instead. Though actually it does not mean the drug is useless for everyone — only that, for this person or this condition, the safe choice is to skip it.

禁忌使用