Diphenhydramine
Medication
sedating antihistamine
allergy
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Sneezing and runny nose; wet cough in the SG syrups
When to take
Every 4–6 hours per the benadryl allergy 25 mg label
Take with
With or without food · half an hour before bed for sleep
Pros & cons
Pros
- HealthHub: with or without food, taken when needed
- Benadryl label: for runny nose, sneezing, itchy eyes
- 9 of 10 SG registrations are pharmacy only
Cons
- Cochrane: no better than placebo for acute cough
- Drowsiness, dry mouth, nausea and vomiting are common
- Benadryl label: not to be used to make a child sleepy
Sources
- HealthHub (MOH Singapore) — Diphenhydramine, uses / administration / precautions / interactions (article last reviewed 3 Jun 2026) · read 2026-08-27
what it says
“antihistamines, which helps to reduce nasal secretions and sneezing … tablets may also be given to help with sleep for short periods … Do not take with or within 14 days of stopping monoamine oxidase inhibitors (MAOIs)”
- MOH National Drug Formulary — PHENEXPECT SYRUP [SIN09014P] (diphenhydramine HCl 12.5 mg/5 ml with ammonium chloride), Indication and Dosing · read 2026-08-27
what it says
“For productive cough; symptomatic relief of sneezing and rhinorrhoea … Adults: 1 to 2 teaspoonfuls to be taken 3 or 4 times a day … 1 teaspoonful is equal to 5 ml”
- MOH National Drug Formulary — PHENEXPECT SYRUP [SIN09014P], Contraindications · read 2026-08-27
what it says
“Ammonium salts are contraindicated in the presence of impaired hepatic or renal function. Patients with narrow angle glaucoma; prostatic hypertrophy. Diphenhydramine may exacerbate porphyria.”
- MOH National Drug Formulary — PAXIDORM TABLETS 25 MG [SIN10851P], product information (no dosing section published) · read 2026-08-27
what it says
“PAXIDORM TABLETS 25 MG [SIN10851P] … DIPHENHYDRAMINE HCL - 25 MG … Licence Holder POLYMEDIC TRADING ENTERPRISE PTE LTD … Forensic Classification PHARMACY ONLY MEDICINES … ATC code R06AA02”
- HSA register of therapeutic products (data.gov.sg d_767279312753558cbf19d48344577084) — 10 diphenhydramine rows, filtered locally 27 Aug 26 · read 2026-08-27
what it says
“PAXIDORM TABLETS 25 mg … Pharmacy Only … PHENEXPECT SYRUP … SUNTUSS SYRUP … DIPRODIN ELIXIR … DIPHEN 10 EXPECTORANT … XSP-BENA EXPECTORANT … BEANAMINE EXPECTORANT … HOVA EXPECTORANT … Prescription Only”
- DailyMed / FDA OTC label — BENADRYL ALLERGY ULTRATABS (diphenhydramine HCl 25 mg tablet), Kenvue Brands LLC, Uses and Directions · read 2026-08-27
what it says
“temporarily relieves … runny nose, sneezing, itchy, watery eyes … take every 4 to 6 hours. do not take more than 6 times in 24 hours … adults and children 12 years and over 1 to 2 tablets”
- DailyMed / FDA OTC label — BENADRYL ALLERGY ULTRATABS, Warnings · read 2026-08-27
what it says
“Do not use to make a child sleepy … with any other product containing diphenhydramine, even one used on skin … children under 6 years do not use … Ask a doctor or pharmacist before use … sedatives or tranquilizers”
- Cochrane Database of Systematic Reviews — OTC medications for acute cough in children and adults in community settings (Smith, Schroeder, Fahey 2014; PMC7061814) · read 2026-08-27
what it says
“Three trials found that antihistamines were no more effective than placebo in relieving cough symptoms … higher numbers of adverse effects in participants taking preparations containing antihistamines and dextromethorphan”
Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.