Many of the steps listed below can be carried out concurrently.
1. Secure the airway. Remember ABC (airway, breathing, circulation).
2. Obtain intravenous access, and administer intravenous fluids.
3. For seizures:
	a. In adults, administer diazepam (Valium) intravenously in a dose of 5 to 10 mg, and repeat the dose if necessary.
	b. In children, administer diazepam intravenously in a dose of 0.25 to 0.40 mg per kg, up to 10 mg per dose. The dose can be repeated if necessary.
4. Obtain arterial blood gases. If the pH is 7.1 or less, give sodium bicarbonate, 1 to 3 mEq per kg intravenously.
5. Replace pyridoxine:
	a. If the amount of ingested isoniazid is known, administer a gram-per-gram dose* of pyridoxine (diluted to a concentration of 50 mL per g) intravenously over five to 10 minutes.† The pyridoxine dose may be repeated every five to 20 minutes until the seizures stop or the patient regains consciousness. Pyridoxine can also be given to resolve residual neurologic defects.
	b. If the amount of ingested isoniazid is unknown, give 5 g of pyridoxine (diluted to 50 mL per g) intravenously over five to 10 minutes.
6. Perform gastric lavage if within one hour of isoniazid ingestion. Remember to protect the airway: use an endotracheal tube with the cuff inflated, or place the patient in the Trendelenburg and left lateral decubitus position.
7. Administer charcoal and sorbitol if within one hour of isoniazid ingestion:
	a. In adults, give 30 to 100 g (1 to 2 g per kg) of charcoal as a slurry with 1 to 2 g per kg of sorbitol, up to 150 g. Repeat the charcoal dose only.
	b. In children, give 15 to 30 g (1 to 2 g per kg) of charcoal as a slurry with 1.0 to 1.5 g per kg of sorbitol, up to 50 g. Repeat the charcoal dose only.
8. If the above methods fail to control seizures, consider hemodialysis or the administration of thiopental by an anesthesiologist.
9. If the patient remains symptomatic, obtain a complete blood count, urinalysis and measurements of electrolytes, blood urea nitrogen, creatinine, glucose, creatinine kinase and liver enzymes. If the patient has liver damage, monitor the prothrombin time or the International Normalized Ratio.