21 CFR § 338.10 - Nighttime sleep-aid active ingredients.

---
identifier: "/us/cfr/t21/s338.10"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 338.10 - Nighttime sleep-aid active ingredients."
title_number: 21
title_name: "Food and Drugs"
section_number: "338.10"
section_name: "Nighttime sleep-aid active ingredients."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "D"
subchapter_name: "DRUGS FOR HUMAN USE"
part_number: "338"
part_name: "NIGHTTIME SLEEP-AID DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 321, 351, 352, 353, 355, 360, 371."
regulatory_source: "54 FR 6826, Feb. 14, 1989, unless otherwise noted."
cfr_part: "338"
---


# 338.10 Nighttime sleep-aid active ingredients.

The active ingredient of the product consists of any of the following when used within the dosage limits established for each ingredient in § 338.50(d):

(a) Diphenhydramine hydrochloride.

(b) Diphenhydramine citrate.