Source: Medicines and Medical Devices Safety Authority (NZ) Revision Year: 2018 Publisher: Pharmaco (NZ) Ltd, 4 Fisher Crescent, Mt Wellington, Auckland 1060, Telephone: 09 377 3336
Premature or newborn infants. Hypersensitivity to the drug. Asthma attack, narrow angle glaucoma, prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstructions, bladder neck obstruction, patients receiving antidepressant therapy.
Both stenosing peptic ulcer and pyloroduodenal obstructions predispose the patient to an increased risk of gastrointestinal obstruction. Agents with anticholinergic properties such as diphenhydramine reduce the tone and motility of the gastrointestinal tract and thus increase the risk of worsening/contributing to gastrointestinal obstruction.
Diphenhydramine has an atropine-like action, which should be considered. Use with caution in those with a history of asthma.
Unisom should be used with caution in subjects with a history of hyper thyroidism, cardiovascular and/or renal disease, hypertension and diabetes.
Use with caution in elderly patients who experience confusion at nighttime.
May have an additive effect when taken with alcohol and other CNS depressants. Avoid alcohol and do not drive a motor vehicle.
Should not be taken in conjunction with other antihistamines, sedatives or tranquilisers except on medical advice.
Do not take with any other product containing diphenhydramine including those applied topically. The terminal half-life may be prolonged in cirrhotic patients.
Antidepressants, particularly of the tricyclic and monoamine oxidase inhibitor types may interact with diphenhydramine. MAO inhibitors prolong and intensify the anticholinergic effects of antihistamines. The CNS effect is increased by alcohol and other CNS depressant drugs.
Unisom (diphenhydramine hydrochloride) produces additive central nervous system effects when taken concomitantly with alcohol, hypnotics, anxiolytics, narcotic analgesics and neuroleptic drugs. Similarly significant interactions may occur if the drug is taken concomitantly with anticholinergic agents or tricyclic antidepressants.
Category A. (Drugs which have been taken by a large number of pregnant women and women of child bearing age without increase in the frequency of malformations or other direct harmful effects on the foetus having been observed).
Diphenhydramine has been detected in breast milk. See Section 4.3.
No fertility information available.
May have an additive effect when taken with alcohol and other CNS depressants. Avoid alcohol and do not drive a motor vehicle.
The most frequently reported adverse reactions are dizziness, dryness of mouth, nose or throat, nausea and nervousness.
Other less frequently reported effects are vertigo, palpitation, blurring of vision, headache, restlessness, insomnia and thickening of bronchial secretions. The following effects may also occur: lassitude, excitement, diplopia, difficulty in urination, constipation, nasal stuffiness, vomiting, drug rash, urticaria, hypotension, photosensitivity, epigastric distress, tightness of the chest and wheezing, excessive perspiration, chills, confusion, restlessness, irritability, diarrhoea or constipation. Rarely prolonged therapy with antihistamines can produce blood dyscrasias.
Reporting suspected adverse reactions after authorisation of the medicine is important. It allows continued monitoring of the benefit/risk balance of the medicine. Healthcare professionals are asked to report any suspected adverse reactions https://nzphvc.otago.ac.nz/reporting/ .
Not applicable.
© All content on this website, including data entry, data processing, decision support tools, "RxReasoner" logo and graphics, is the intellectual property of RxReasoner and is protected by copyright laws. Unauthorized reproduction or distribution of any part of this content without explicit written permission from RxReasoner is strictly prohibited. Any third-party content used on this site is acknowledged and utilized under fair use principles.
