Maximum Recommended Dose of Gravol (Dimenhydrinate) for Adults
The maximum recommended dose of dimenhydrinate (Gravol) for adults is 400 mg per day, typically administered as 50-100 mg every 4-6 hours as needed.
Dosing Guidelines
Standard Adult Dosing
- Regular dose: 50 mg every 4-6 hours as needed
- Higher dose: 100 mg every 4-6 hours may be used when drowsiness is not objectionable or is desirable
- Maximum daily dose: 400 mg (not to exceed this amount in a 24-hour period)
Administration Routes
- Oral: Available as tablets, capsules, or liquid formulations
- Injectable: For situations when oral administration is impractical
- Intramuscular: 50 mg (1 mL) as needed
- Intravenous: 50 mg diluted in 10 mL of 0.9% Sodium Chloride Injection, administered over 2 minutes
Safety Considerations
Potential Side Effects
- Common side effects include drowsiness, dizziness, dry mouth, and blurred vision
- Higher doses may cause significant sedation, confusion, and anticholinergic effects
Precautions
- Use with caution in patients with:
- Glaucoma
- Prostatic hypertrophy
- Asthma or COPD
- Cardiovascular disease
- Hepatic or renal impairment
Risk of Abuse
- Dimenhydrinate has potential for abuse at high doses (>300 mg)
- Supratherapeutic doses (1000-2400 mg/day) have been associated with euphoria, hallucinations, and dependence 1
- Patients taking doses exceeding 300 mg should be evaluated for potential misuse 2
Special Situations
Toxicity Management
- Patients 6 years and older who ingest ≥7.5 mg/kg or ≥300 mg (whichever is less) should be referred to an emergency department 2
- Symptoms of overdose include severe anticholinergic effects, agitation, hallucinations, seizures, and potentially QRS prolongation
Duration of Treatment
- For most indications (motion sickness, nausea, vomiting), limit treatment to the shortest duration necessary to control symptoms
- Extended use should be monitored by a healthcare provider
Important Considerations for Clinical Practice
- The FDA drug label specifically indicates that 50 mg every 4 hours is sufficient to control nausea and vomiting in most adults 3
- When administering higher doses (100 mg), be aware of the increased risk of sedation and anticholinergic side effects
- Monitor patients receiving maximum doses for adverse effects, particularly elderly patients who may be more sensitive to anticholinergic effects
Remember that dimenhydrinate contains diphenhydramine combined with 8-chlorotheophylline, and both components contribute to its pharmacological effects and side effect profile.