Meclizine (Antivert)

ED / ICU / Transport

• Acute vertigo from peripheral vestibular disease (vestibular neuritis, labyrinthitis): short-term symptom relief. Address a central cause such as posterior-circulation stroke first. The FDA label covers vertigo from vestibular disease in adults.
• Ménière disease attacks: a limited course for vertigo during the attack itself. It is not maintenance therapy.
• BPPV: routine vestibular suppressants are not recommended (AAO-HNS BPPV guideline and GRACE-3). Treat it with a repositioning maneuver. A few days may help, but only in select patients with mild residual symptoms after a successful maneuver (Dix–Hallpike now negative).
• Who may give it: an oral antivertigo drug. An RN or paramedic may give it per protocol or order. The National EMS Scope of Practice Model does not name it, and national guidance does not treat it as an EMS-carried drug. It varies by state, agency and facility protocol.

Other Uses

• Motion sickness: prevention and treatment of nausea, vomiting and dizziness. OTC labeling covers adults and children 12 years and older.

Doses vary by protocol; follow local protocols and medical direction.

Available Forms

• Prescription tablets: 12.5 mg, 25 mg and 50 mg (swallow whole)
• Prescription chewable tablets: 25 mg (chew or crush completely)
• OTC motion-sickness products: 25 mg tablets and chewables (Bonine, Dramamine Less Drowsy, store brands), a 50 mg chewable (Bonine Max, 1 tablet once daily) and orally disintegrating forms; check the strength per unit

Adult Dosing

Pediatric Dosing

Preparation & Administration

• Tablets: swallow whole
• Chewable tablets: chew or crush completely before swallowing; do not swallow whole
• Motion sickness timing: give the first dose 30–60 min before travel starts; follow the product label (some, such as Bonine Max, say 1 hr)
• Discharge counseling: no driving or hazardous work until the response is known; no alcohol; use for the shortest time

Renal and hepatic notes: see Special Populations.

Contraindications

• Hypersensitivity to meclizine or any inactive ingredient (anaphylaxis has been reported)

Precautions

• Undifferentiated or possibly central vertigo: evaluate for posterior-circulation stroke first (HINTS by a trained clinician, gait, neuro exam). Do not treat the symptom and discharge.
• Glaucoma, enlarged prostate, asthma or chronic lung disease (emphysema, chronic bronchitis): anticholinergic effects can make each one worse.
• Older adults: watch for confusion, urinary retention and falls. AGS Beers Criteria 2023 says avoid it.
• Driving and hazardous tasks: drowsiness is common. Avoid alcohol.
• Hepatic or renal impairment, CYP2D6 poor metabolizers: exposure may rise. Use with caution.

Hold / Reassess If

• New focal deficit, inability to walk, severe headache or a central HINTS pattern: stop, treat as possible stroke
• New confusion or agitation, or no urine output with a full bladder: hold, assess for anticholinergic toxicity
• Eye pain, blurred vision or halos: hold, check for acute angle-closure glaucoma

Common

• Drowsiness and fatigue
• Dry mouth
• Headache
• Vomiting

The label gives no frequencies for these, or for anaphylaxis. Class anticholinergic effects are missing from the label: constipation and urinary hesitancy, more likely in older adults.

Rare: blurred vision and anaphylaxis (below).

Serious / Life-Threatening

Overdose & Toxicity Management

• Picture: anticholinergic toxidrome: delirium with hallucinations, dilated pupils, tachycardia, dry flushed skin, hyperthermia, urinary retention, ileus; seizures or coma in severe cases
• Immediate management: airway, glucose, ECG, temperature; call Poison Control (1-800-222-1222). Benzodiazepines (e.g. lorazepam) for seizures; for agitation, a moderate initial dose only, because escalating doses can worsen delirium and raise the risk of intubation (physostigmine, with toxicology input, is preferred for confirmed antimuscarinic delirium when not contraindicated); active cooling for hyperthermia; bladder catheter for retention; avoid physical restraints
• Physostigmine (no E3 page yet): for agitated antimuscarinic delirium, with toxicology input: adult 1 mg IV slowly over 5 min, may repeat 1 mg after 10–15 min; stop if heart rate falls below 70/min. Do not give with QRS >100–120 ms, PR >200 ms or higher-degree AV block, heart rate below about 80/min (an anticholinergic toxidrome should cause tachycardia), mechanical urinary or bowel obstruction, coma with an unprotected airway, a proconvulsant co-ingestion or a suspected tricyclic co-ingestion. Pediatric dose per toxicology
• Decontamination: consider activated charcoal in hospital once the airway is protected

• Neuro and gait: before the first dose and before discharge; new deficit, central HINTS pattern or inability to walk: stroke pathway, not discharge
• Sedation and mental status: 30–60 min after a dose and at each check; new confusion in an older adult: stop and review anticholinergic load
• Fall risk: every assessment; unsteady gait: assist ambulation, fall precautions, safe-discharge plan
• Urine output and bladder: in men with an enlarged prostate and older adults; inability to void: bladder scan and catheterize if retained
• Response and duration: reassess symptoms; still needing it after 3–5 days or worsening: specialist referral and vestibular rehabilitation rather than more meclizine

Clinically Significant Interactions

It is oral only, so IV compatibility never comes up.

• Pediatrics: prescription use (for vertigo) is not established in children. OTC motion-sickness dosing starts at age 12. See the Pediatric Dosing table.
• Pregnancy: Epidemiological studies have not shown a higher risk of major birth defects. Rat studies showed fetal malformations at about 2 times the maximum human dose. Use it when the benefit is clear.
• Lactation: The label has no human milk data. LactMed says occasional doses are probably acceptable. Large or prolonged doses may sedate the infant or reduce milk supply, especially with a decongestant such as pseudoephedrine, or before lactation is established.
• Older Adults: AGS Beers Criteria 2023 says avoid (highly anticholinergic: confusion, constipation, urinary retention; strong recommendation). Falls are a particular risk. If you use it, start at the low end of the dosing range and keep the course short.
• Renal Impairment: It has not been studied. The drug or its metabolites may build up. No specific adjustment is established, so use with caution.
• Hepatic Impairment: It has not been studied. Reduced metabolism may raise exposure. No specific adjustment is established, so use with caution.
• CYP2D6 Poor or Ultrarapid Metabolizers: Genetic variation can cause large differences in exposure. Watch for excess sedation or poor effect.
• Obesity / Dosing Weight: Doses are fixed. There is no weight-based adjustment.

Mechanism of Action

• It is a piperazine H1-receptor antagonist (the labeled mechanism is presumed to be H1 blockade). That reduces vestibular and vomiting-center signaling, so you get less vertigo and nausea.
• Central antimuscarinic (anticholinergic) activity gives an antiemetic effect. It also brings sedation, confusion, dry mouth and urinary retention.
• Vestibular suppression gives symptom relief, but continued use slows central compensation.

Pharmacokinetics

• Half-life: about 5–6 hr
• Metabolism: hepatic, CYP2D6 dominant; CYP2D6 polymorphism causes wide variation in exposure
• Distribution: not characterized in humans

Generic Name

Meclizine hydrochloride

Brand Names

Antivert (Rx); OTC: Bonine, Bonine Max, Dramamine Less Drowsy and other meclizine Dramamine products, store brands; multiple generics

Pharmacologic Class

First-generation (piperazine) H1 antihistamine with anticholinergic activity

Therapeutic Class

Antivertigo agent; antiemetic for motion sickness

Controlled Substance

Not controlled

ISMP High-Alert

No

Look-Alike / Sound-Alike

Brand-family trap: Dramamine Original Formula (dimenhydrinate) / Dramamine Less Drowsy, All Day, Nausea and some chewables (meclizine); Bonine and Bonine Max (meclizine) / Bonine for Kids (chlorcyclizine); check the active ingredient