Meclizine Dosing for Adults
The recommended dose of meclizine for adults is 25 to 100 mg daily, administered orally in divided doses, depending on clinical response. 1
Standard Dosing Regimen
- Initial dose: Start with 25 mg daily and titrate upward based on symptom control 1
- Typical range: 25-100 mg per day, divided into multiple doses 1
- Administration: Tablets must be swallowed whole; do not crush or chew 1
- Timing: Take after meals to minimize gastrointestinal upset (based on general antihistamine principles)
Available Formulations
- Tablet strengths: 12.5 mg, 25 mg, and 50 mg 1
- The 50 mg tablets are scored and can be divided if needed for dose adjustment 1
Clinical Indications
- FDA-approved use: Treatment of vertigo associated with vestibular system diseases in adults 1
- Off-label use: Motion sickness prophylaxis, though transdermal scopolamine provides superior protection 2
Pharmacokinetic Considerations
- Onset of action: Approximately 1 hour for standard tablet formulations 3
- Peak concentration (Tmax): 3-4 hours after administration 4
- Half-life: Approximately 7-8 hours 4
- Metabolism: Primarily via CYP2D6, which exhibits genetic polymorphism and can cause significant interindividual variability 3
- Steady state: Achieved after approximately 10-14 days of repeated dosing 4
Critical Safety Warnings
- Drowsiness: May cause significant sedation; patients must avoid driving or operating dangerous machinery 1
- Alcohol interaction: Avoid concurrent use with alcohol or other CNS depressants due to additive sedation 1
- Anticholinergic effects: Use with caution in patients with asthma, glaucoma, or prostatic enlargement 1
- Drug interactions: CYP2D6 inhibitors may increase meclizine levels and adverse effects; monitor accordingly 1
Contraindications
- Hypersensitivity: Contraindicated in patients with known hypersensitivity to meclizine or any inactive ingredients 1
Common Adverse Effects
- Drowsiness, dry mouth, headache, fatigue, and vomiting are the most frequently reported adverse reactions 1
- Blurred vision occurs rarely 1
- Anaphylactic reactions have been reported 1
Special Populations
- Pregnancy: Limited human data available; animal studies showed fetal malformations at clinically relevant doses; use only if benefit outweighs risk 1
- Elderly: May require dose reduction due to increased sensitivity to anticholinergic effects (based on general geriatric principles)
- Renal/hepatic impairment: No specific dosing adjustments provided in FDA labeling, but caution is warranted 1