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Chlorpheniramine

Medication first-generation antihistamine allergycold & flu
Aka: chlorphenamine, Piriton, CPM
Brands seen in Singapore: Allersin, Antamin, Axcel Chlorpheniramine, Chloramine, Horamine
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, runny nose and itch from allergies, cold or flu
When to take
Every 4 to 6 hours per label · when symptoms need it
Take with
With or without food · water, milk or juice (NHS)
Pros & cons
Pros
  • NHS: usually takes 30 minutes to 1 hour to work
  • Covers allergy and cold/flu runny nose (HealthHub)
  • SG: pharmacy-only — no prescription needed (HSA)
Cons
  • Sedating — drowsiness usually lasts 4 to 6 hours (NHS)
  • Dry mouth, blurred vision, trouble concentrating (NHS)
  • Confusion in the elderly or very young (HealthHub)
Sources
  1. HSA — Listing of Registered Therapeutic Products (open dataset on data.gov.sg, resource d_767279312753558cbf19d48344577084, pulled via datastore_search API; 30 chlorpheniramine/dexchlorpheniramine rows read) · read 2026-08-27
    what it says
    “ANTAMIN TABLET 4 mg · CHLORPHENIRAMINE MALEATE · Pharmacy Only — ALLERSIN SYRUP 4 mg/5 ml · Pharmacy Only — CHLORAMINE TABLET 4 mg · Pharmacy Only — PIRIMAT INJECTION 10 mg/ml · Prescription Only”
  2. HSA — List of reclassified medicines (forensic classification definitions: POM / P / GSL) · read 2026-08-27
    what it says
    “Pharmacy-Only Medicine (P): A therapeutic product that can be obtained from a pharmacist at a retail pharmacy without a prescription … generally indicated for the short-term treatment of a minor condition or symptoms … managed by self-medication”
  3. HealthHub (MOH Singapore) — Chlorpheniramine medication information leaflet (article last reviewed 3 June 2026) · read 2026-08-27
    what it says
    “Chlorpheniramine belongs to a group of medicines known as antihistamines … Relief of sneezing due to allergies … Relief of runny nose due to allergies, cold or flu … Relief of itch in the eyes, nose or skin”
  4. HealthHub (MOH Singapore) — Chlorpheniramine leaflet, 'how should I take' section (same page) · read 2026-08-27
    what it says
    “You may take this medication with or without food … Take this medication when necessary to relieve your symptoms … Do not exceed the maximum dose as recommended by your healthcare professional”
  5. HealthHub (MOH Singapore) — Chlorpheniramine leaflet, precautions and side-effects sections (same page) · read 2026-08-27
    what it says
    “You have or have ever had: Increased eye pressure (glaucoma) … Difficulty urinating or have a history of other bladder conditions … Seizures … Abnormal heart rhythm … Liver disease … Confusion in the elderly or very young children”
  6. HealthHub (MOH Singapore) — Chlorpheniramine leaflet, food and medication interactions section (same page) · read 2026-08-27
    what it says
    “Avoid alcoholic drinks as this may increase drowsiness … Do not take with or within 14 days of stopping monoamine oxidase inhibitors (MAOIs) such as moclobemide and selegiline … check with your health care professional before taking two over-the-counter medications”
  7. NHS — About chlorphenamine (brand names Piriton, Allerief, Pollenase; page last reviewed 14 May 2025) · read 2026-08-27
    what it says
    “Chlorphenamine is an antihistamine medicine that relieves the symptoms of allergies. It's known as a drowsy (sedating) antihistamine … Chlorphenamine usually takes 30 minutes to 1 hour to work … Wait at least 4 hours between doses”
  8. NHS — How and when to take chlorphenamine, 'Dosage and strength' (page last reviewed 14 May 2025) · read 2026-08-27
    what it says
    “The usual dose for adults and children aged 12 years old or over is 1 tablet every 4 to 6 hours. Do not take more than 6 tablets in 24 hours … Chlorphenamine comes as 4mg tablets”
  9. NHS — How and when to take chlorphenamine, older adults and duration (same page) · read 2026-08-27
    what it says
    “The usual dose for older adults who are frail is 1 tablet every 6 to 8 hours. Do not take more than 3 tablets in 24 hours … Do not take chlorphenamine for longer than 2 weeks”
  10. NHS — Side effects of chlorphenamine (page last reviewed 14 May 2025) · read 2026-08-27
    what it says
    “Drowsiness usually wears off 4 to 6 hours after a dose … Feeling dizzy or difficulty concentrating … Dry mouth … Blurred vision … Children and people aged over 65 have more chance of getting some side effects”
  11. DailyMed / FDA — ALLER-CHLOR (chlorpheniramine maleate 4 mg) tablet, OTC Drug Facts 'Directions' (Rugby Laboratories; label updated 8 July 2026) · read 2026-08-27
    what it says
    “Chlorpheniramine maleate 4 mg … Antihistamine … take every 4 to 6 hours, or as directed by a doctor … adults and children 12 years and over 1 tablet. Do not exceed 6 tablets in 24 hours”
  12. DailyMed / FDA — ALLER-CHLOR, OTC Drug Facts 'Warnings' (same label) · read 2026-08-27
    what it says
    “Ask a doctor before use if you have glaucoma, a breathing problem such as emphysema or chronic bronchitis, difficulty in urination due to enlargement of the prostate gland … excitability may occur, especially in children”
  13. DailyMed / FDA — ALLER-CHLOR, OTC Drug Facts drowsiness and drug-interaction warnings (same label) · read 2026-08-27
    what it says
    “Ask a doctor or pharmacist before use if you are taking sedatives or tranquilizers … alcohol, sedatives, and tranquilizers may increase drowsiness … use caution when driving a motor vehicle or operating machinery”
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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.