The probability of benefit generally outweighs the risk of adverse reactions for antidotes such as N-acetylcysteine used for treatment of paracetamol (acetaminophen) poisoning, and naloxone used in opioid poisoning. For some antidotes, such as dicobalt edetate in cyanide poisoning, administration carries high risk, and the clinical decision to use the antidote is only taken in severe poisoning.
Use of an antidote rarely replaces the need for supportive measures. Except for N-acetylcysteine in paracetamol poisoning, the clinical state and not plasma concentration dictates whether an antidote is used. In pregnancy, it is usually reasoned that treatment of the mother takes precedence and provides the best chance for fetal survival, notwithstanding worries about teratogenicity.