The lowest published toxic dose (TDLo) from oral administration in man is 51 mg/kg. The oral LD₅₀ is 400 mg/kg and the subcutaneous LD₅₀ is 100 mg/kg in mice.^L11196

The signs and symptoms of overdose are typically observed within 15 to 20 minutes and can lead to neurological and cardiovascular toxicity, which is related to blocked sodium channels. Intentional and unintentional death from overdose may occur. The risk of overdose is highest in children and toxicity may result from the ingestion of 1 or 2 capsules in this age group.^A5790 If capsules are chewed or dissolved in the mouth, oropharyngeal anesthesia will develop rapidly, which may cause choking and a compromised airway function. Symptoms arising from CNS stimulation include restlessness and tremors, which may lead to clonic convulsions followed by profound CNS depression. Within 1 hour following ingestion, convulsions, coma, cerebral edema and cardiac arrest leading to death have been reported.^L11193

Evacuation of gastric contents and administration of copious amounts of activated charcoal is advised. It is important to note that cough and gag reflexes may be significantly depressed even in conscious patients with overdose; special attention is needed to protect against aspiration of gastric contents. When intravenously administering short-acting barbiturates to treat convulsions, the dose should be carefully titrated for the smallest effective dose. Overdose should be managed with supportive care with continuous monitoring of neurologic and cardiovascular status. Intensive support of respiration and cardiovascular-renal function should be initiated for severe intoxication.^L11193 Because benzonatate is structurally similar to local anesthetic agents, the use of intravenous lipid emulsion therapy in response to life-threatening cardiovascular collapse is also suggested.^A5790