Overview
Chlorpheniramine maleate is a first-generation antihistamine commonly used for symptomatic relief of allergic conditions and cold symptoms. It works by competitively blocking histamine H1 receptors, reducing symptoms like sneezing, runny nose, and itching. It is available in various over-the-counter formulations, often combined with other cold/flu medications.
Mechanism of Action
Chlorpheniramine maleate is a propylamine derivative antihistamine that competitively antagonizes histamine at H1 receptors. It prevents histamine-mediated responses in the respiratory tract, blood vessels, and gastrointestinal smooth muscle, reducing symptoms of allergic reactions and upper respiratory conditions.
Indications
- Temporary relief of common cold symptoms including sneezing, runny nose, and nasal congestion
- Relief of cough due to minor throat and bronchial irritation
- Reduction of sinus congestion and pressure
- Promotion of nasal/sinus drainage and thinning of bronchial secretions
Common Doses
- 4 mg tablets
- 8 mg extended-release tablets
- 2 mg/5 mL syrup
- 10 mg/mL injection
Dosage
Adults and children 12 years and over: 30 mL every 4-6 hours, not to exceed 4 doses in 24 hours. Children 6 to under 12 years: 15 mL every 4-6 hours. Children 4 to under 6 years: consult doctor. Children under 4 years: do not use. Always use provided dose cup and take only as directed.
Contraindications
- Hypersensitivity to chlorpheniramine or any component of the formulation
- Concurrent use with monoamine oxidase inhibitors (MAOIs) or within 2 weeks of discontinuing MAOI therapy
- Neonates and premature infants
- Patients with narrow-angle glaucoma, urinary retention, or severe hypertension
Side Effects
- Drowsiness, sedation, dizziness
- Dry mouth, nose, and throat
- Blurred vision
- Gastrointestinal disturbances (nausea, vomiting)
- Urinary retention
- Headache
- Excitation (especially in children)
- Rare: paradoxical CNS stimulation, hypersensitivity reactions
Interactions
- MAO inhibitors: risk of hypertensive crisis
- Alcohol and other CNS depressants: additive sedation
- Anticholinergic drugs: increased anticholinergic effects
- Other antihistamines: additive effects
Counseling Points
- May cause drowsiness; avoid alcohol and activities requiring alertness
- Use provided measuring device for accurate dosing
- Do not exceed recommended dose or frequency
- Consult doctor if symptoms persist beyond 7 days or worsen
- Keep out of reach of children
- Shake well before use if suspension