Acute poisoning by organophosphorus (OP) compounds is a major global clinical 
problem, with thousands of deaths occurring every year. Most of these pesticide 
poisoning and subsequent deaths occur in developing countries following a 
deliberate self ingestion of the poison. Metacid (Methyl parathion) and Nuvan 
(Dichlorovos) are commonly ingested OP pesticides; Dimethoate, Profenofos, and 
Chlorpyrifos are other less frequently ingested compounds in Nepal. The toxicity 
of these OP pesticides is due to the irreversible inhibition of 
acetylcholinesterase (AChE) enzyme leading to accumulation of acetylcholine and 
subsequent over-activation of cholinergic receptors in various parts of the 
body. Acutely, these patients present with cholinergic crisis; intermediate 
syndrome and delayed polyneuropathy are other sequel of this form of poisoning. 
The diagnosis depends on the history of exposure to these pesticides, 
characteristic manifestations of toxicity and improvements of the signs and 
symptoms after administration of atropine. The supportive treatment of OP 
poisoning includes the same basic principles of management of any acutely 
poisoned patient i.e., rapid initial management of airways, breathing, and 
circulation. Gastric lavage and activated charcoal are routinely used 
decontamination procedures, but their value has not been conclusively proven in 
this poisoning. Atropine is the mainstay of therapy, and can reverse the life 
threatening features of this acute poisoning. However, there are no clear cut 
guidelines on the dose and duration of atropine therapy in OP poisoning. 
Cholinesterase reactivators, by regenerating AChE, can reverse both the 
nicotinic and muscarinic effects; however, this benefit has not been translated 
well in clinical trials. All these facts highlight that there are many 
unanswered questions and controversies in the management of OP poisoning and 
there is an urgent need for research on this aspect of this common and deadly 
poisoning.