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Dytan Side Effects

Generic Name: diphenhydramine

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 Dytan.

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]

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]


Common (1% to 10%): Dry mouth
Frequency not reported: Gastrointestinal disturbance, nausea, vomiting, constipation, diarrhea, dyspepsia, epigastric distress[Ref]


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]


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]


Rare (0.01% to 0.1%): Palpitations, hypotension, arrhythmia
Frequency not reported: Tachycardia, chest tightness, extrasystoles[Ref]


Rare (0.01% to 0.1%): Blood disorders
Frequency not reported: Hemolytic anemia, thrombocytopenia, agranulocytosis[Ref]


Rare (0.01% to 0.1%): Hypersensitivity reactions
Frequency not reported: Angioedema, anaphylactic shock[Ref]


Rare (0.01% to 0.1%): Liver dysfunction[Ref]


Frequency not reported: Rash, urticaria, skin rashes, erythema, photosensitivity, pruritus, drug rash, excessive perspiration[Ref]


Frequency not reported: Dyspnea, thickening of bronchial secretions, throat tightening, wheezing, nasal stuffiness, dry nose or throat[Ref]


Frequency not reported: Urinary hesitancy/difficulty/retention, dysuria, early menses[Ref]


Frequency not reported: Blurred vision, dry eyes, diplopia[Ref]


Frequency not reported: Increased appetite, anorexia[Ref]


Frequency not reported: Muscle twitching/weakness[Ref]


1. Cerner Multum, Inc. "Australian Product Information." O 0

2. "Product Information. Benadryl Childrens Allergy Fastmelt (diphenhydrAMINE)." Pfizer U.S. Pharmaceuticals Group, New York, NY.

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

4. "Product Information. Benadryl (diphenhydramine)." Parke-Davis, Morris Plains, NJ.

Some side effects of Dytan may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.