Meclizine
Meclizine hydrochloride
Brand names:Antivert, Bonine, Dramamine Less Drowsy
A piperazine-class H1 antihistamine with central anticholinergic activity used for motion sickness and vertigo. Meclizine is the preferred oral antiemetic for vestibular indications when the operator must remain functional: it has less sedation than dimenhydrinate and provides 24-hour protection from a single dose. Less effective than scopolamine patch for sustained operations but more accessible.
Pharmacology and Actions
Meclizine is a piperazine H1 antihistamine with central anticholinergic activity. It suppresses vestibular and labyrinthine signaling to the central nervous system, blunting motion sickness and vertigo. Less sedating than first-generation antihistamines like diphenhydramine and dimenhydrinate due to lower blood-brain barrier penetration.
Indications
- Motion sickness prevention
- Vertigo associated with vestibular disorders (Meniere disease, labyrinthitis, vestibular neuronitis)
- Benign positional vertigo (acute symptomatic management)
Absolute Contraindications
- Known hypersensitivity to meclizine
- Children under 12 years (safety not established)
Precautions and Side Effects
Drowsiness occurs but is significantly less than dimenhydrinate. Anticholinergic effects: dry mouth, blurred vision, urinary retention, constipation. CNS: headache, fatigue. Rare: tachycardia, hypotension. Drug interactions: additive sedation with alcohol, opioids, benzodiazepines, and other CNS depressants (less pronounced than dimenhydrinate); additive anticholinergic effects with TCAs, antipsychotics, and other antihistamines. Half-life 5 to 6 hours but duration of action is 8 to 24 hours due to tissue distribution. Pregnancy Category B (used for motion sickness in pregnancy, though dimenhydrinate has more pregnancy data). Small amounts in breast milk; generally considered compatible. Cautious use in narrow-angle glaucoma, prostatic hyperplasia, asthma, and pyloroduodenal obstruction. Anticholinergic burden in elderly - use with caution.
Adult Dosing
Pediatric Dosing
Not recommended under 12 years. Children 12 years and older: same as adult.
Pharmacokinetics
Peak Effect: 1 to 3 hours.
Duration: 8 to 24 hours (the operational advantage - single tablet covers an extended water or rotary-wing operation).
Storage and Handling
Store at room temperature. Protect from light and moisture. Stable in standard aid bag conditions.
Reconstitution:
Oral formulation only. Chewable tablets are useful when water is limited or quick onset is preferred.
TCCC and TECC Role
Meclizine is not in the TCCC core formulary. It appears in tactical EMS supplemental formularies as the preferred oral antiemetic for motion sickness and vertigo when the operator must remain functional. The 24-hour duration is the operational advantage - one tablet covers an extended water or rotary-wing operation. Mission impact is minor at standard doses, distinguishing meclizine from dimenhydrinate in operational tolerability.
Meclizine is the better tactical motion sickness option compared with dimenhydrinate when sedation must be minimized. The 25 mg dose is usually well tolerated in operators who tolerate caffeine and a normal sleep schedule. For maximum operational protection during prolonged water operations or high-vibration environments, scopolamine transdermal patch is still preferred - longer duration (3 days), less anticholinergic burden, and less sedation than meclizine. Meclizine fills the gap when patches are unavailable or contraindicated.
Reaching for meclizine for routine post-trauma nausea or post-opioid nausea instead of ondansetron. Meclizine works on vestibular nausea; it is not a first-line antiemetic for opioid-related, chemotherapy-related, or trauma-related nausea. The other mistake is treating it as fully non-sedating - some operators are quite sensitive and become significantly impaired. Test tolerance during training before relying on it operationally.
This drug profile is provided as educational reference material for trained medical providers. It is not medical advice, not a substitute for formal training, and not a substitute for current published guidelines or medical direction.
Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances are subject to additional handling, accountability, and documentation requirements per DEA and state law. Always verify dosing, indications, contraindications, and route of administration against current published guidelines and your local protocols before administration.
If this content is being viewed during a medical emergency, call 911 immediately and follow the direction of your local emergency dispatch and medical control. Do not use this reference as a substitute for emergency medical services.
Drug information evolves. Last reviewed dates and source citations are provided for each entry. Confirm currency against the cited source before clinical use.
Penn Tactical Solutions publishes this reference for educational purposes. PTS does not provide medical direction and does not assume responsibility for clinical decisions made in the field. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Educational reference for trained medical providers. Not medical advice. Not a substitute for formal training, current published guidelines, or medical direction. Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances require additional storage, accountability, and documentation per DEA and state law.
In a medical emergency, call 911. This reference is not a substitute for emergency medical services.
Verify dosing, indications, and contraindications against current published guidelines and your local protocols before administration. Confirm content currency against the source citation. Penn Tactical Solutions does not provide medical direction. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Meclizine
| IV/IO | None (None) |
| IM | None (None) |
| IN | None (None) |
| PO | Motion sickness: 25 to 50 mg PO 1 hour before travel; may repeat every 24 hours. Vertigo: 25 to 100 mg PO daily in divided doses. Chewable tablets (12.5 mg, 25 mg) and standard tablets (12.5 mg, 25 mg, 50 mg) are available. (1 hour) |