The clinician should suspect which poisoning in a family with sudden onset headache after decorating the Christmas tree?

• A. Methanol poisoning
• B. Carbon monoxide poisoning
• C. Cyanide poisoning
• D. Organophosphate poisoning

Answer: (B)

Exposure to carbon monoxide in an enclosed space from incomplete combustion is the key idea. When a family uses gas heaters, fireplaces, or a generator indoors or in poorly ventilated areas, carbon monoxide can accumulate without noticeable odor or scent. Inhalation causes carboxyhemoglobin formation, which reduces the blood’s ability to deliver oxygen to the brain and other tissues. The brain is especially sensitive to hypoxia, so headache can be an early and prominent symptom, often accompanied by dizziness, weakness, nausea, or confusion. This pattern fits a sudden headache after being in a closed room during a winter activity like decorating, where a heater or other fuel-burning device may be in use.

This fits better than other options because methanol poisoning typically follows ingestion or exposure to methanol-containing products and presents with vision problems and metabolic acidosis rather than a sudden indoor headache. Cyanide poisoning often stems from smoke inhalation in fires and presents with rapidly progressive confusion, seizures, and severe hypoxia, usually in an acute fire setting. Organophosphate poisoning causes a cholinergic syndrome—salivation, lacrimation, urination, defecation, GI distress, emesis, along with pinpoint pupils and bradycardia—not the isolated sudden headache pattern described.