Chlorphenamine — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Chlorphenamine?
Chlorphenamine (chlorpheniramine) is a first-generation sedating antihistamine for allergic conditions and acute allergic reactions. This medication is funded by Pharmac (injection); available in OTC combination products.
What is Chlorphenamine Used For?
Used for hay fever, urticaria, allergic conjunctivitis, insect bites, and as a component of cold and flu preparations. IV injection used for acute severe allergic reactions.
How Does Chlorphenamine Work?
Blocks H1 receptors with CNS penetration, causing sedation alongside antiallergic effects. Also has mild anticholinergic properties.
How to Take Chlorphenamine
Adults: 4 mg every 4–6 hours (max 24 mg/day). Take at bedtime if sedation is a concern. Injection used for acute allergic reactions.
Common Side Effects of Chlorphenamine
- Drowsiness and sedation (significant)
- Dry mouth
- Blurred vision
- Urinary hesitancy
- Constipation
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Paradoxical excitation in children
- Urinary retention in BPH
- Anticholinergic toxidrome at high doses
Drug Interactions
Chlorphenamine may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- CNS depressants and alcohol (additive sedation)
- MAOIs (contraindicated)
- Anticholinergic medicines (additive)
New Zealand Prescribing Information
Chlorphenamine maleate 4 mg tablets and 10 mg/mL injection (Piriton® and generics) are funded by Pharmac. For routine daytime allergy management, a non-sedating second-generation antihistamine is strongly preferred. Chlorphenamine at bedtime can be useful when itch from hives or skin conditions disrupts sleep.
Frequently Asked Questions
Can I drive after taking chlorphenamine?
No — chlorphenamine causes significant sedation. Do not drive or operate machinery after taking it.
When is chlorphenamine preferred over non-drowsy antihistamines?
When itch is preventing sleep — its sedative properties help patients rest while managing the allergic reaction.
References & Further Information
The following New Zealand and international resources were used to inform this page:
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ