Chlorpheniramine Maleate Dosage and Usage for Allergy Relief
For adults and children 12 years and over, take 1 tablet (4 mg) every 4 to 6 hours, not exceeding 6 tablets (24 mg) in 24 hours. For children 6 to under 12 years, take 1/2 tablet (2 mg) every 4 to 6 hours, not exceeding 3 tablets (12 mg) in 24 hours. Children under 6 years should not use chlorpheniramine maleate. 1
Mechanism and Clinical Uses
Chlorpheniramine maleate is a first-generation H1 antihistamine that works by blocking histamine receptors, thereby reducing allergic symptoms. It's commonly used for:
- Allergic rhinitis (hay fever)
- Common cold symptoms 2
- Urticaria (hives)
- Allergic reactions
- As adjunctive therapy in anaphylaxis (not as first-line treatment) 3
Age-Specific Dosing
Adults and Children 12+ years:
- 4 mg (1 tablet) every 4-6 hours
- Maximum: 24 mg (6 tablets) per 24 hours
Children 6-12 years:
- 2 mg (1/2 tablet) every 4-6 hours
- Maximum: 12 mg (3 tablets) per 24 hours
Children under 6 years:
- Not recommended 1
Special Populations
Renal Impairment
- Avoid in severe renal impairment (creatinine clearance <10 mL/min) 3
Hepatic Impairment
- Avoid in severe liver disease as its sedating effect may precipitate coma 3
Pregnancy
- Best to avoid all antihistamines in pregnancy, especially during the first trimester
- If antihistamine therapy is necessary during pregnancy, chlorpheniramine is often chosen by clinicians due to its long safety record 3
Use in Anaphylaxis
When used in anaphylaxis management, chlorpheniramine is administered as adjunctive therapy, not as a replacement for epinephrine:
Adult dosage for anaphylaxis (adjunctive therapy):
- 10 mg IM or IV slowly 3
Pediatric dosage for anaphylaxis (adjunctive therapy):
- 6 to 12 years: 5 mg IM or IV slowly
- 6 months to 6 years: 2.5 mg IM or IV slowly
- Under 6 months: 250 μg/kg IM or IV slowly 3
Important Considerations
Sedation: Chlorpheniramine is a first-generation antihistamine with significant sedative properties (approximately 50% sedation potential) 4. Patients should be warned about potential drowsiness and advised against driving or operating machinery.
Anticholinergic Effects: May cause dry mouth, blurred vision, urinary retention, and constipation.
Drug Interactions: Use with caution when combined with:
- CNS depressants (alcohol, sedatives, hypnotics)
- MAO inhibitors
- Drugs metabolized by cytochrome P450 3
Elderly Patients: First-generation antihistamines like chlorpheniramine should be avoided in elderly patients due to high risk of cognitive impairment and significant anticholinergic effects 4.
Timing Considerations: For allergy symptoms that worsen at night, taking a dose before bedtime may be beneficial as the sedative effects can aid sleep.
Alternative Options
For patients concerned about sedation, second-generation antihistamines may be preferable:
- Loratadine (10 mg once daily, 8% sedation potential)
- Fexofenadine (180 mg once daily, 1.3% sedation potential)
- Desloratadine (5 mg once daily, 2.1% sedation potential) 4
Cautions and Contraindications
- Avoid in patients with narrow-angle glaucoma
- Use with caution in patients with prostatic hypertrophy, bladder neck obstruction
- Contraindicated in patients with known hypersensitivity to chlorpheniramine (rare but documented cases of chlorpheniramine-induced anaphylaxis exist) 5
- Should not be used as primary treatment for anaphylaxis; epinephrine is the first-line treatment 3
Chlorpheniramine remains a useful antihistamine for allergy relief, particularly when sedation is not a concern or might be beneficial (such as for nighttime symptom relief). However, its significant sedative and anticholinergic effects make second-generation antihistamines preferable for many patients, especially the elderly or those who need to remain alert.