Diphenhydramine hydrochloride; Benadryl

03/04/2009 19:48

Diphenhydramine hydrochloride

Brand Name: Benadryl, Tusstat

Pregnancy Category B

Drug classes: Antihistamine, Anti-motion sickness agent, Sedative/hypnotic, Antiparkinsonian agent, Cough suppressant


Therapeutic actions

Competitively blocks the effects of histamine at H1-receptor sites, has atropine-like, antipruritic, and sedative effects.



· Relief of symptoms associated with perennial and seasonal allergic rhinitis; vasomotor rhinitis; allergic conjunctivitis; mild, uncomplicated urticaria and angioedema; amelioration of allergic reactions to blood or plasma; dermatographism; adjunctive therapy in anaphylactic reactions

· Active and prophylactic treatment of motion sickness

· Nighttime sleep aid

· Parkinsonism (including drug-induced parkinsonism and extrapyramidal reactions), in the elderly intolerant of more potent agents, for milder forms of the disorder in other age groups, and in combination with centrally acting anticholinergic antiparkinsonian drugs

· Suppression of cough due to colds or allergy (syrup formulation)


· Contraindicated with allergy to any antihistamines, third trimester of pregnancy, lactation.


Adverse effects

Drowsiness, sedation, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, headache, blurred vision, diplopia

Hypotension, palpitations, bradycardia, tachycardia, extrasystoles

Epigastric distress, anorexia, increased appetite and weight gain, nausea, vomiting, diarrhea or constipation

Urinary frequency, dysuria, urinary retention, early menses, decreased libido, impotence

Hemolytic anemia, hypoplastic anemia, thrombocytopenia, leukopenia, agranulocytosis, pancytopenia

Thickening of bronchial secretions, chest tightness, wheezing, nasal stuffiness, dry mouth, dry nose, dry throat, sore throat

Urticaria, rash, anaphylactic shock, photosensitivity, excessive perspiration


Drug Interactions:

· Possible increased and prolonged anticholinergic effects with MAO inhibitors

Nursing considerations

· Administer with food if GI upset occurs.

· Administer syrup form if patient is unable to take tablets.

· Monitor patient response, and arrange for adjustment of dosage to lowest possible effective dose.