Background: A first-generation antihistamine called diphenhydramine is used to treat cold and allergic rhinitis symptoms. Diphenhydramine reduces the effects of endogenous histamine on bronchial, capillary, and gastrointestinal smooth muscles by competitively inhibiting the histamine-1 (H1) receptor.
Objective: The present study was designed to evaluate the effectiveness of the antihistamine diphenhydramine in improving survival and controlling seizures in insecticide-treated mice.
Methods: Mice (males and females) were divided into (4) equal groups and treated as follows: The 1st group: was the control group (physiological saline solution + lambda-cyhalothrin at 150 mg/kg orally). 2nd group: (Diphenhydramine 10 mg/kg subcutaneously + lambda-cyhalothrin 150 mg/kg orally), 3rd group (atropine sulfate 15 mg/kg subcutaneously + lambda-cyhalothrin 150 mg/kg orally) and 4th Group (Diazepam 10 mg/kg subcutaneously + lambda-cyhalothrin 150 mg/kg orally) Diphenhydramine, atropine sulfate, and diazepam were injected 15 min before the oral administration of  lambda-cyhalothrin to mice . Mice were monitored for 30 min after treatment. The onset of signs of toxicity, the time of onset of neurological seizures, and their number with the extraction of the toxicity rank value were recorded.
Results: Diphenhydramine at 10 mg/kg subcutaneously (15) minutes before oral administration of lambda-cyhalothrin  at 150 mg/kg causes a slight decrease in the time of signs onset of acute toxicity compared to the control group with a slight decline in the time of the onset of nervous seizures compared to the control group, and diphenhydramine at dose of 10 mg/kg of caused a decrease in the number of seizures and onset min respectively compared to the control group, with complete prevention of death within 24 hour in all treated mice and a reduction in toxicity scores (22), compared to the control group (28).
Conclusion: Our results showed that diphenhydramine had an anticonvulsive effect on the neurological convulsions induced by lambda-cyhalothrin poisoning and the possibility of its use in controlling it and reducing the severity of signs of poisoning due to its anti-muscarinic and nicotine effects.