Neuroleptic malignant syndrome. A potentially fatal reaction that most often occurs as a result of the use of antipsychotic drugs. It is characterised by fever, muscle rigidity, rhabdomyolysis (muscle breakdown), profuse sweating, tachycardia, tachypnoea (rapid breathing), agitation.
Serotonin syndrome similar to neuroleptic malignant syndrome but develops more rapidly (over a period of hours instead of days/weeks for neuroleptic malignant syndrome)