Poisoning can be due to exposure to organophosphates, which inhibit cholinesterase activity and may cause cholinergic toxicity. Organophosphates are used in insecticides and nerve agents. Toxic levels may be ingested, inhaled, or absorbed through the skin. Organophosphate poisoning may occur due to the ingestion of contaminated food or exposure to contaminated clothing. Inhalational or oral exposure results in symptoms within 3 hours, while cutaneous absorption may take up to 12 hours before affected individuals are symptomatic.

There are 3 associated presentations:

• The initial presentation is characterized by cholinergic excess and classified as acute muscarinic and nicotinic cholinergic toxidromes. Findings include nausea, diarrhea, bronchospasm, hypoxia, decreased heart rate, fatigue, presyncope, headache, lacrimation, blurry vision, miosis, sweating, salivation, seizures, coma, muscle weakness, and fasciculation.
• An intermediate syndrome may occur 1-4 days after exposure (following the acute presentation) and consists of neurologic symptoms such as weak respiratory muscles, weak proximal limb muscles, and affected cranial nerves. With appropriate care, these effects should resolve completely within 3 weeks.
• A delayed syndrome occurs 1-3 weeks following exposure, and findings include painful paresthesias and weak extremities. This may result in permanent complications such as poor memory and parkinsonism. Recovery from these delayed symptoms is variable.

The progression of immediate to intermediate to delayed symptoms is dose dependent on the initial organophosphate toxin exposure.