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Meclizine (also spelled meclozine; brand names Bonine and Antivert) is a long-acting first-generation piperazine antihistamine used chiefly for motion sickness and vertigo. It blocks histamine H1 receptors and central muscarinic acetylcholine receptors, dampening vestibular and emetic signaling; this same anticholinergic activity allows it to produce a deliriant, confusional state at high doses, alongside sedation from H1 blockade. It is metabolized largely by CYP2D6, giving wide interindividual variation in exposure and onset. Beyond its antihistamine role, meclizine has drawn research interest for an unusual metabolic action, partially inhibiting mitochondrial oxidative phosphorylation and redirecting energy production toward glycolysis, an effect studied for neuroprotection and cytoprotection.
- Prevents and treats motion sickness
- Relieves vertigo from inner-ear or vestibular disorders
- Eases associated nausea and dizziness
- Long-acting vestibular H1 and muscarinic blockade
- Drowsiness and fatigue
- Dry mouth and blurred vision
- Confusion, especially in older adults
- Delirium and toxidrome at high doses
Mechanism
Meclizine antagonizes H1 receptors, and it also blocks receptors. Its anti-motion-sickness and anti-vertigo effects come from dampening signaling in the vestibular system (the inner-ear balance apparatus) and the vomiting-control centers in the brainstem, where both histamine and acetylcholine pathways feed nausea and dizziness. Its central H1 blockade also causes sedation. The same muscarinic antagonism that quiets the balance system drives the anticholinergic toxidrome at high doses, producing delirium along with the peripheral dry, hot, flushed, tachycardic picture.
receptor fingerprint
H1 receptorAntagonist
receptorsAntagonist
Safetyrisks and cautions, not medical advice
At high doses meclizine causes anticholinergic delirium with realistic hallucinations mistaken for reality, confusion and memory loss, plus the toxidrome: blurred vision, dangerous overheating, flushed dry skin, dry mouth, racing heart, urinary retention and seizures. Combining it with other anticholinergics or sedating antihistamines stacks anticholinergic burden and increases the risk, and its sedation compounds with alcohol and other depressants. High anticholinergic burden is linked to greater dementia risk in the elderly and with long-term use. Not medical advice.
Interactionsdocumented pairs only, not exhaustive
Meclizine is metabolized chiefly by CYP2D6, confirmed in human liver microsome and recombinant enzyme work, and variation in that enzyme explains much of the wide spread in blood levels between people. Strong CYP2D6 inhibitors such as paroxetine, fluoxetine, bupropion and quinidine raise exposure and with it the sedation and dry mouth.
The interactions that actually cause trouble are additive rather than metabolic. Alcohol, benzodiazepines, opioids, sedating antidepressants and gabapentinoids compound drowsiness and impair coordination out of proportion to either drug alone. Anticholinergic load stacks the same way: tricyclics, oxybutynin, low-potency antipsychotics and other first-generation antihistamines taken with meclizine can produce confusion, urinary retention, constipation and, in older adults, frank delirium.
Because meclizine suppresses vestibular signaling, it can also mask the early dizziness that signals aminoglycoside ototoxicity, which delays recognition of hearing damage.
Checking a whole stack? Run it through interactions + stacks.
Subjective profileweighing the evidence above
Dependable for motion sickness and vertigo, and the once-daily dosing is a genuine convenience. The anticholinergic side is the catch; it makes you drowsy, and in older adults it causes real confusion, so it is a poor pick there. At high doses it produces full anticholinergic delirium.
Resources
This entry is here for reference.
Research
- 1999first citedPhysiological and behavioral effects of an antivertigo antihistamine in adults.
- 2022most recentThe anticholinergic burden: from research to practice
- 1.The effects of meclizine on motion sickness revisited
- 2.Meclizine metabolism and pharmacokinetics: formulation on its absorption
- 3.The anticholinergic burden: from research to practice
- 4.Evaluation of the effects of anti-motion sickness drugs on subjective sleepiness and cognitive performance of healthy males.
- 5.Stimulation of the semicircular canals via the rotary chair as a means to test pharmacologic countermeasures for space motion sickness.
- 6.Physiological and behavioral effects of an antivertigo antihistamine in adults.
- 7.Induction of apoptosis and cell-cycle arrest in human colon cancer cells by meclizine.
- 8.Altered Energy Metabolism During Early Optic Nerve Crush Injury: Implications of Warburg-Like Aerobic Glycolysis in Facilitating Retinal Ganglion Cell Survival.
8 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Why does meclizine help motion sickness?
It blocks histamine H1 and muscarinic receptors in the vestibular (inner-ear balance) system and brainstem nausea centers, quieting the signals that cause dizziness and vomiting.
Is meclizine less sedating than other antihistamines?
It is often described as relatively less drowsy than some, but it still causes meaningful sedation and carries the same anticholinergic risks at high doses.
Can you overdose on it?
Yes. Large amounts cause an anticholinergic delirium and toxidrome that are dangerous and unpleasant, with no recreational benefit.
Adverse effects
- Drowsiness and fatigue
- Dry mouth and blurred vision
- Confusion, especially in older adults
- Delirium and toxidrome at high doses