contraindication

n. symptom or condition that indicates the inadvisability of a particular treatment (Medical)

In medicine, a contraindication is a condition or factor that increases the risks involved in using a particular drug, carrying out a medical procedure or engaging in a particular activity.The opposite of contraindication is indication.
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Noun
1. (medicine) a reason that makes it inadvisable to prescribe a particular drug or employ a particular procedure or treatment
(antonym) indication
(hypernym) reason
(derivation) contraindicate
(classification) medicine, medical specialty

(n.)
An indication or symptom which forbids the method of treatment usual in such cases.
  

A symptom or medical condition that makes a particular treatment or procedure inadvisable because a person is likely to have a bad reaction. For example, having a bleeding disorder is a contraindication for taking aspirin because treatment with aspirin may cause excess bleeding.