In medicine, a<unk>  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.
Some<unk> s are absolute, meaning that there are no reasonable circumstances for undertaking a course of action.  For example, a baby with a fever should never be given aspirin because of the risk of Reye's syndrome, and a person with a severe food allergy should never eat that food.
Other<unk> s are relative, meaning that the patient is at higher risk of complications, but that these risks may be outweighed by other considerations or mitigated by other measures.  For example, a pregnant woman should normally avoid getting X-rays, but the risk may be far less than the risk of not diagnosing or being able to treat a serious condition such as tuberculosis or a broken bone.
Contraindication
Informed consent
Complication 
Avolition
Defence mechanism
Withdrawal of consent
Chain of survival
Residency 