Note: This document contains side effect information about diphenhydramine. Some dosage forms listed on this page may not apply to the brand name Unisom SleepGels.
Summary
More frequent side effects include: sedated state and thickening of bronchial secretions. Continue reading for a comprehensive list of adverse effects.
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.
General
The most commonly reported side effects included somnolence, dizziness, and incoordination.[Ref]
Nervous system
Common (1% to 10%): Sedation/somnolence/sleepiness, drowsiness, unsteadiness, dizziness, headache, attention disturbance
Rare (0.01% to 0.1%): Extrapyramidal effects, tremor, convulsions
Frequency not reported: Paresthesia, dyskinesia/muscle dyskinesia, vertigo, neuritis, incoordination, psychomotor impairment, activation of epileptogenic foci[Ref]
Drowsiness usually diminishes after a few days.[Ref]
Gastrointestinal
Common (1% to 10%): Dry mouth
Frequency not reported: Gastrointestinal disturbance, nausea, vomiting, constipation, diarrhea, dyspepsia, epigastric distress[Ref]
Other
Common (1% to 10%): Fatigue
Frequency not reported: Lassitude, tinnitus, acute labyrinthitis, asthenia, chills, impaired performance (including impaired driving, work, and/or information processing)[Ref]
Psychiatric
Rare (0.01% to 0.1%): Confusion, depression, sleep disturbances
Frequency not reported: Paradoxical excitation/excitation, agitation, increased energy, restlessness, nervousness, euphoria, anxiety, hallucinations, insomnia, irritability[Ref]
Cardiovascular
Rare (0.01% to 0.1%): Palpitations, hypotension, arrhythmia
Frequency not reported: Tachycardia, chest tightness, extrasystoles[Ref]
Hematologic
Rare (0.01% to 0.1%): Blood disorders
Frequency not reported: Hemolytic anemia, thrombocytopenia, agranulocytosis[Ref]
Hypersensitivity
Rare (0.01% to 0.1%): Hypersensitivity reactions
Frequency not reported: Angioedema, anaphylactic shock[Ref]
Hepatic
Rare (0.01% to 0.1%): Liver dysfunction[Ref]
Dermatologic
Frequency not reported: Rash, urticaria, skin rashes, erythema, photosensitivity, pruritus, drug rash, excessive perspiration[Ref]
Respiratory
Frequency not reported: Dyspnea, thickening of bronchial secretions, throat tightening, wheezing, nasal stuffiness, dry nose or throat[Ref]
Genitourinary
Frequency not reported: Urinary hesitancy/difficulty/retention, dysuria, early menses[Ref]
Ocular
Frequency not reported: Blurred vision, dry eyes, diplopia[Ref]
Metabolic
Frequency not reported: Increased appetite, anorexia[Ref]
Musculoskeletal
Frequency not reported: Muscle twitching/weakness[Ref]