SHEET /m/diphenhydramine · PubChem CID 3100 · CAS 58-73-1 · REV 2026.07
Diphenhydramine from source
C17H21NO · 255.35 g/mol
Benzhydramine · Alledryl · Probedryl · Dihidral
Also sold as Benadryl, ZzzQuil, Sominex from source
antihistamine medication
Fig. 1 · 2D structure RDKit
CN(C)CCOC(C1=CC=CC=C1)C2=CC=CC=C2
Where you'll find it
Not yet mapped to everyday foods or products.
The dose makes the poison inferred
A reported rat oral LD50 for Diphenhydramine is 500 mg/kg, the dose lethal to half the animals tested. Scaled by body mass alone:
“The dose makes the poison” is a cross-species estimate shown as neutral science, not a threshold anyone should act on. Real toxicity depends on the person, not body mass alone.
Toxicity & hazards
Toxicity · LD50
500 mg/kg · low toxicity · LD50 rat oral from source
The dose lens above scales this to a body weight.
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