ZzzQuil Side Effects
Generic Name: diphenhydramine
Medically reviewed by Drugs.com. Last updated on Oct 5, 2020.
Note: This document contains side effect information about diphenhydramine. Some of the dosage forms listed on this page may not apply to the brand name ZzzQuil.
More frequent side effects include: sedated state and thickening of bronchial secretions. See below for a comprehensive list of adverse effects.
For the Consumer
Applies to diphenhydramine: oral capsules and tablets, parenteral injection
Side effects include:
Sedation, sleepiness, dizziness, disturbed coordination, epigastric distress, thickening of bronchial secretions.
For Healthcare Professionals
Applies to diphenhydramine: compounding powder, injectable solution, oral capsule, oral disintegrating strip, oral liquid, oral tablet, oral tablet chewable, oral tablet disintegrating
The most commonly reported side effects included somnolence, dizziness, and incoordination.[Ref]
Common (1% to 10%): Sedation/somnolence/sleepiness, drowsiness, unsteadiness, dizziness, headache, attention disturbance
Rare (0.01% to 0.1%): Extrapyramidal effects, tremor, convulsions
Drowsiness usually diminishes after a few days.[Ref]
Common (1% to 10%): Dry mouth
Common (1% to 10%): Fatigue
Rare (0.01% to 0.1%): Confusion, depression, sleep disturbances
Rare (0.01% to 0.1%): Blood disorders
Rare (0.01% to 0.1%): Hypersensitivity reactions
Rare (0.01% to 0.1%): Liver dysfunction[Ref]
Frequency not reported: Blurred vision, dry eyes, diplopia[Ref]
Frequency not reported: Increased appetite, anorexia[Ref]
1. Cerner Multum, Inc. "Australian Product Information." O 0
2. "Product Information. Benadryl (diphenhydramine)." Parke-Davis, Morris Plains, NJ.
3. "Product Information. Benadryl Childrens Allergy Fastmelt (diphenhydrAMINE)." Pfizer U.S. Pharmaceuticals Group, New York, NY.
4. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
Frequently asked questions
- How much Benadryl can I take? What is too much?
- Diphenhydramine Hydrochloride vs Citrate: What's the difference?
More about ZzzQuil (diphenhydramine)
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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Some side effects may not be reported. You may report them to the FDA.