From the Guidelines
Yes, dimenhydrinate and meclizine work in similar ways, primarily as antihistamines that block histamine H1 receptors in the brain to reduce symptoms of motion sickness, vertigo, and nausea. Both medications, dimenhydrinate (commonly sold as Dramamine) and meclizine (often marketed as Antivert or Bonine), affect the vestibular system in the inner ear, which controls balance and spatial orientation 1. The main difference between them is their duration of action - meclizine typically lasts longer (12-24 hours) compared to dimenhydrinate (4-6 hours), making meclizine more convenient for once-daily dosing. Meclizine also tends to cause less drowsiness than dimenhydrinate, though both can have sedative effects. For motion sickness prevention, dimenhydrinate is usually taken 30-60 minutes before travel at 50-100mg doses, while meclizine is typically taken 1 hour before travel at 25-50mg doses.
Key Differences and Considerations
- Duration of action: Meclizine lasts longer than dimenhydrinate, which may influence the choice based on the patient's needs and preferences.
- Sedative effects: Meclizine tends to cause less drowsiness, which is an important consideration for patients who need to remain alert.
- Dosage and administration: The dosages and timing of administration differ between the two medications, which should be considered for optimal effectiveness and minimal side effects.
Clinical Evidence and Recommendations
The most recent and highest quality study, from 2017, indicates that vestibular suppressant medications, including antihistamines like dimenhydrinate and meclizine, are not recommended for the treatment of Benign Paroxysmal Positional Vertigo (BPPV) except for short-term management of autonomic symptoms such as nausea or vomiting in severely symptomatic patients 1. This study highlights the potential for significant harm from these medications, including drowsiness, cognitive deficits, and an increased risk of falls, especially in the elderly. Therefore, the use of dimenhydrinate and meclizine should be carefully considered, weighing the potential benefits against the risks, and alternative treatments such as repositioning maneuvers should be prioritized for BPPV.
From the FDA Drug Label
INDICATIONS AND USAGE Dimenhydrinate Injection, USP is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness. INDICATIONS AND USAGE Meclizine hydrochloride tablets are indicated for the treatment of vertigo associated with diseases affecting the vestibular system in adults (1).
The FDA drug labels for dimenhydrinate 2 and meclizine 3 indicate that both are used to treat vertigo, but the specific conditions and contexts differ.
- Dimenhydrinate is used for motion sickness.
- Meclizine is used for vertigo associated with diseases affecting the vestibular system. The labels do not provide information on the mechanisms of action, so it is unclear if they work in similar ways.
From the Research
Mechanism of Action
- Dimenhydrinate and meclizine are both antihistamines that can cause central nervous system effects, including drowsiness and impairment of mental performance 4.
- The study found that both dimenhydrinate and meclizine produced changes in digit symbol substitution, recognition time, and subjective assessments of sleepiness different from placebo 4.
- The effects of dimenhydrinate on psychometric test scores were compared with the magnitude of the effects produced by subsequent doses, suggesting the possibility that acute tolerance to central nervous system impairment develops with multiple doses of dimenhydrinate 4.
Comparison of Dimenhydrinate and Meclizine
- The greatest reductions in digit symbol substitution scores after dimenhydrinate occurred 3 hours after the first dose, and were not different from the greatest measured change after meclizine, which occurred 9 hours after the dose 4.
- Self-rated sleepiness after dimenhydrinate was greatest 1 hour after the first dose, and was significantly greater than the largest degree of sleepiness after meclizine, which occurred at 7 hours after the dose 4.
- The study suggests that dimenhydrinate and meclizine work in similar ways, but with some differences in the timing and magnitude of their effects 4.
Irrelevant Study
- There is a study on fatty tumors of the thorax demonstrated by CT, but it is not relevant to the comparison of dimenhydrinate and meclizine 5.