Toxicology histories are notoriously unreliable.

Any available medical records, especially medication lists.

Timing & amount of ingestions. Immediate vs. sustained-release formulations.

Consider inquiring specifically about the ingestion of acetaminophen or acetaminophen-containing combination pills (e.g., over the counter sleep aids, or combination cold remedies).

Collateral information from first responders, family, and pharmacies may help.

In general, histories should be used only to broaden the differential diagnosis, rather than to narrow it:

If the patient doesn’t recall taking something, that doesn’t exclude it with certainty.

If the patient reports taking something, that is a likely intoxicant (although this doesn’t exclude coingestions).

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