Allerdryl , Banophen, Belix, Ben-Allergin, Bena-D, Benadryl, Benadryl Dye-Free, Benahist, Benoject, Benylin, Compoz, Diahist, Dihydrex, Diphen, Diphenacen-50, Fenylhist, Hyrexin, Insomnal, Nordryl, Nytol with DPH, Sleep-Eze 3, Sominex Formula 2, Tusstat, Twilite, Valdrene, Wehdryl
Classifications: antihistamine; h1-receptor antagonist
Pregnancy Category: C
25 mg, 50 mg capsules, tablets; 6.25 mg/5 mL, 12.5 mg/5 mL syrup; 50 mg/mL injection
H1-receptor antagonist and antihistamine with significant anticholinergic activity. High incidence of drowsiness, but GI side effects are minor. Effects in parkinsonism and drug-induced extrapyramidal symptoms are apparently related to its ability to suppress central cholinergic activity and to prolong action of dopamine by inhibiting its reuptake and storage.
Competes for H1-receptor sites on effector cells, thus blocking histamine release.
Temporary symptomatic relief of various allergic conditions and to treat or prevent motion sickness, vertigo, and reactions to blood or plasma in susceptible patients. Also used in anaphylaxis as adjunct to epinephrine and other standard measures after acute symptoms have been controlled; in treatment of parkinsonism and drug-induced extrapyramidal reactions; as a nonnarcotic cough suppressant; as a sedative-hypnotic; and for treatment of intractable insomnia.
Hypersensitivity to antihistamines of similar structure; lower respiratory tract symptoms (including acute asthma); narrow-angle glaucoma; prostatic hypertrophy, bladder neck obstruction; GI obstruction or stenosis; pregnancy (category C), lactation, premature neonates, and neonates; use as nighttime sleep aid in children <12 y.
History of asthma; convulsive disorders; increased IOP; hyperthyroidism; hypertension, cardiovascular disease; diabetes mellitus; older adults, infants, and young children.
|Allergy Symptoms, Antiparkinsonism, Motion Sickness, Nighttime Sedation
Adult: PO 2550 mg t.i.d. or q.i.d. (max: 300 mg/d) IV/IM 1050 mg q46h (max: 400 mg/d)
Child: PO/IV/IM 26 y, 6.25 mg q46h (max: 300 mg/24 h); 612 y, 12.525 mg q46h (max: 300 mg/24 h)
Adult: PO 25 mg q46h (max: 100 mg/d)
Child: PO 26 y, 6.25 mg q46h (max: 25 mg/24 h); 612 y, 12.5 mg q46h (max: 50 mg/24 h)
PREPARE: Direct: Give undiluted.
ADMINISTER: Direct: Give at a rate of 25 mg or a fraction thereof over 1 min.
INCOMPATIBILITIES Y-site: Furosemide.
In common with other antihistamines, diphenhydramine should be discontinued 4 d prior to skin testing procedures for allergy because it may obscure otherwise positive reactions.
Assessment & Drug Effects
Patient & Family Education