Meclozine
H1 antihistamines
H1 antihistamines
A piperazine antihistamine used to prevent and treat nausea, vomiting and dizziness of motion sickness and vertigo.
Also called: Meclizine
Quick facts
- Group
- H1 antihistamines
- Target
- Histamine H1 receptor
- Used for
- Prevention and treatment
- Key effects
- Drowsiness · Dry mouth · Blurred vision
- Monitor
- Sedation and fall risk · Symptom control
- ATC
- R06AE05
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows doxepin, a tricyclic first-generation H1 blocker, in the human H1 receptor; meclozine is thought to act at the same receptor.
Meclozine is a first-generation H1 antihistamine with central antimuscarinic action. It reduces signals from the inner ear (vestibular system) to the vomiting centre, which is why it works for motion sickness and vertigo. It is most effective when taken before symptoms start. Drowsiness and anticholinergic effects are common.
- Motion stimulates the inner ear and sends signals to the brainstem
- Meclozine blocks H1 and muscarinic receptors on that pathway
- Fewer signals reach the vomiting centre
- Nausea and dizziness are reduced, with some drowsiness
Indications
- Prevention and treatment of motion sickness
- Vertigo from vestibular disorders Ménière disease →
Adverse effects
Common
- Drowsiness
- Dry mouth
- Blurred vision
- Tiredness
Contraindications
- Hypersensitivity to meclozine
- Caution in glaucoma, asthma and prostate enlargement
- Older adults: avoided where possible because of confusion, falls and urinary retention
Key interactions
- Alcohol, benzodiazepines, opioids and other CNS depressants
- Additive sedation and slowed breathing
- Other anticholinergic drugs (tricyclic antidepressants, oxybutynin, antipsychotics)
- Additive dry mouth, urinary retention, constipation and confusion
What is monitored
- Sedation and fall risk
- Symptom control
Administration and safety
- Tablets, chewable tablets or capsules by mouth, taken before the trip starts
Pregnancy and breastfeeding
Meclozine has been used for nausea in pregnancy; use is decided with the clinician.
Nursing care
- Explain that it works better before symptoms begin
- Teach not to drive or operate machinery until the effect is known, and to avoid alcohol
- Assess fall risk in older adults with vertigo
Pharmacokinetics
- Absorption
- Oral
- Metabolism
- Liver
- Onset and duration
- Works best when taken before travel; effect lasts many hours
Test yourself
Think of the answer, then tap the question to see it.
When is meclozine most effective for motion sickness?
When taken before the motion and symptoms begin.
Which sensory system's signals does meclozine damp down?
The vestibular system of the inner ear.
What are two anticholinergic side effects of meclozine?
Dry mouth and blurred vision (also urinary retention).
Connections
← Back to the class: H1 antihistamines
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Meclizine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2018); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.