Overview
Chlorpheniramine is a first-generation antihistamine used for symptomatic relief of allergic conditions and common cold symptoms. It works by blocking histamine H1 receptors, reducing symptoms like sneezing, runny nose, and itchy eyes. It is available in various formulations including oral liquids, tablets, and combination products.
Mechanism of Action
Chlorpheniramine is a competitive antagonist at histamine H1 receptors, preventing histamine-mediated allergic responses. It also exhibits anticholinergic and sedative properties due to its ability to cross the blood-brain barrier.
Indications
- Temporary relief of common cold symptoms: sneezing, runny nose
- Temporary relief of nasal congestion, sinus congestion and pressure
- Relief of cough due to minor throat and bronchial irritation
- Reduction of swelling in nasal passages to restore freer breathing
- Promotion of nasal and/or sinus drainage
Common Doses
- 4 mg tablets
- 8 mg extended-release tablets
- 2 mg/5 mL syrup
- 1 mg/mL oral solution
- Combination products with varying strengths
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 14 days of discontinuing MAOI therapy
- Use to make a child sleepy
- Neonates and premature infants
Side Effects
- Drowsiness, sedation
- Dry mouth, nose, and throat
- Dizziness
- Headache
- Nausea
- Nervousness
- Blurred vision
- Urinary retention
- Paradoxical excitation (especially in children)
Interactions
- Monoamine oxidase inhibitors (MAOIs): risk of severe hypertensive crisis
- Alcohol and other CNS depressants: increased sedation
- Anticholinergic drugs: additive anticholinergic effects
- Drugs metabolized by CYP2D6: potential interactions
Counseling Points
- May cause drowsiness; avoid driving or operating machinery
- Use provided measuring device for accurate dosing
- Do not exceed recommended dosage
- Avoid alcohol and other sedating medications
- Consult doctor before use in children under 6 years
- Discontinue use and consult doctor if symptoms worsen or persist beyond 7 days