chlorphenamine maleate at a glance
Medicine class
Sedating first-generation H1 antihistamine
Main role
Relieves allergic itching, hives, swelling and rhinitis
Alertness
Can cause sleepiness, dizziness, blurred vision and impaired concentration
Available forms
Selected products include tablets, syrup and solution for injection
What is chlorphenamine maleate used for?
Selected products are licensed to relieve symptoms of:
Hay fever and vasomotor rhinitis
Hives, angioedema and other allergic swelling or itching
Reactions to food, medicines, serum, insect bites or stings
Severe non-specific itching and desensitisation reactions with selected injections
Acute allergic reactions in healthcare settings; injection is an adjunct in anaphylaxis, not a substitute for adrenaline
How does chlorphenamine maleate work?
It blocks histamine at H1 receptors, reducing itching, swelling, sneezing and nasal or eye symptoms. It also enters the brain and has antimuscarinic activity, explaining effects such as sedation, dry mouth and blurred vision.
chlorphenamine maleate preparations and strengths
Syrup
Route: Oral
Strengths: 2 mg/5 mL
Tablet
Route: Oral
Strengths: 4 mg
Injection
Route: Parenteral
Strengths: 10 mg/mL
How to take chlorphenamine maleate
Follow the product leaflet and directions from your pharmacist or prescriber because suitability varies by formulation and age.
Swallow tablets with water, milk or juice, with or without food.
Measure oral liquid with the supplied oral syringe or medicine spoon, not a kitchen teaspoon.
Check combination cough, cold and allergy products to avoid another antihistamine.
Injection is administered by a healthcare professional.
Do not drive, cycle or operate machinery if sleepy, dizzy, unable to concentrate or affected by blurred vision.
chlorphenamine maleate side effects
Common or expected effects
- Sleepiness or sedation
- Dizziness, headache or difficulty concentrating
- Dry mouth
- Nausea
- Blurred vision
- Tiredness
Get urgent medical advice
- Call 999 for throat or tongue swelling, severe breathing difficulty or collapse.
- Seek urgent medical advice for difficulty passing urine, jaundice, or unusual bruising or bleeding.
- Seizures, severe agitation, hallucinations, abnormal heart rhythm, breathing problems or unconsciousness may indicate serious toxicity, particularly after overdose.
chlorphenamine maleate in pregnancy
Available evidence does not suggest harm, and chlorphenamine can be used when recommended by a doctor. Product information is more cautious, particularly near the end of pregnancy because neonatal reactions are possible. Ask a prescriber or pharmacist; a less-sedating antihistamine may be preferred.
chlorphenamine maleate while breastfeeding
A non-sedating antihistamine is generally preferred for a healthy, full-term breastfed infant. If a sedating antihistamine is required, UK specialist guidance considers chlorphenamine the preferred option with caution. Monitor the infant for unusual sleepiness, irritability, dry mouth, poor feeding or inadequate weight gain. Seek professional advice, especially for a premature or unwell infant or repeated use.
chlorphenamine maleate interactions
Check all prescribed, pharmacy and combination products before use.
Monoamine oxidase inhibitors, such as phenelzine
Antimuscarinic and sedative effects may be dangerously increased; selected products contraindicate current or recent use.
Alcohol
Can increase sleepiness and impairment, so concurrent use should be avoided.
Common questions about chlorphenamine maleate
Answers are fully visible for fast scanning and source review.
How quickly does it start working?
After oral administration, symptom relief commonly begins within about 30 minutes to one hour, although response varies.
Why can it cause sleepiness?
It enters the brain and blocks central H1 receptors, which can reduce alertness and cause sedation.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.