Meclizine for Dogs: Dosage Chart, Car Sickness and Safety

Meclizine is the human travel-sickness antihistamine sold as Bonine, Dramamine Less Drowsy and Antivert. Vets use it in dogs "extra-label", meaning outside its human label, to ease car sickness and the nausea and dizziness of vestibular disease.

Two things to know before you reach for the box: the Merck Veterinary Manual lists meclizine as an amount per dog, not per kilogram, so there is no reliable weight chart to dose from at home. And the Dramamine and Bonine names also cover two other drugs, so the box in your cabinet may not be meclizine at all. Your vet decides whether your dog gets it and how much.

Meclizine Dosage for Dogs: Chart and Calculator

The chart shows the two amounts the Merck Veterinary Manual publishes for dogs. The car-travel row comes first because that's why most people give it.

Only give what your vet prescribed, at the dose they set.

For information only. These are typical published dose ranges, not a prescription and not medically verified for your pet. Your veterinarian sets the dose after examining your pet. Never start, stop or change a medicine without their OK.

What the chart can't tell you:

• Merck lists a per-dog amount, not per-kg; your vet adjusts for your dog's size. Neither Merck page splits the amount by weight. We found no veterinary source for the weight-band charts that circulate online, so we don't show one.
• The two Merck pages disagree. The motion-sickness table gives 12.5 mg every 12 hours. The antihistamine table gives 12.5 to 50 mg once a day. Your vet decides which fits your dog.
• Tablet size is not a dose. Meclizine comes as 12.5, 25, 30 and 50 mg tablets and 25 mg capsules, according to PetPlace, all sized for adult people.
• Not for every dog. PetMD says not to give it to pregnant dogs or puppies under 6 months. The chart is for dogs only; cats are covered at the end.
• Too much, or got into the bottle? Call now: your vet, the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661.

Is the Box in Your Cabinet Actually Meclizine?

It's an easy mistake. Travel-sickness brands sell more than one drug under the same name, and only the active ingredient line tells you which one you're holding. Here is what the current US labels on DailyMed list (checked November 2026):

Dimenhydrinate and cyclizine are not interchangeable with meclizine, and the chart above doesn't apply to them. If the box doesn't say meclizine, ask your vet before giving it.

Check the inactive ingredients too. The chewables we checked are sweetened with saccharin, aspartame, sorbitol or sugars. None of those labels lists xylitol, but formulas differ by maker and change over time, and xylitol is toxic to dogs. Show the package to your vet. A plain tablet your vet names is the simplest choice.

Why Dogs Get Car Sick, and How Meclizine Helps

Car sickness starts in the inner ear. The vestibular system, the balance sensors there, feels the car turn and brake while the eyes and body report that the dog is sitting still. The brain gets two stories at once, and nausea follows. In dogs, histamine-using nerve cells and the brain's vomiting trigger zone are part of that pathway, which is why an antihistamine like meclizine can calm it, according to the Merck Veterinary Manual.

Signs of car sickness to watch for:

• drooling, lip licking or smacking
• restlessness, pacing or whining
• panting in a dog that isn't hot
• low energy, or not wanting to move
• vomiting, and sometimes passing stool

Puppies get it most. Their inner-ear balance structures are still developing, and many outgrow car sickness by about 1 year of age, according to VCA Animal Hospitals. That's the frustrating part: the dogs most likely to be car sick are often too young for meclizine. For a young puppy, ask your vet about conditioning and other options.

A dog whose early rides ended in vomiting, or always at the vet, can also start to dread the car. Meclizine settles nausea; it does not treat fear. VCA notes that anti-nausea drugs won't touch that anxiety, and your vet may suggest a behavior plan instead.

How to Give Meclizine Before a Car Trip

Your vet's instructions come first. General guidance from veterinary drug references:

• Give it 30 to 60 minutes before you leave, says VCA. Merck's table says about 1 hour before travel; Veterinary Partner says about 30 minutes.
• It can be given with or without food (Veterinary Partner).
• The anti-nausea effect lasts about 6 hours, according to Veterinary Partner. Effects can last longer in dogs with liver or kidney disease (VCA).
• Missed a dose in a dog that takes it daily, for example for vestibular disease? Give it when you remember, but Veterinary Partner advises waiting at least 6 to 8 hours before the next one. Never give two doses at once.
• Store it at room temperature in a closed container, away from light and moisture.

Car Trip Prep That Works Without Pills

For many dogs, practice does more than any tablet. VCA Animal Hospitals and the Merck Veterinary Manual both put conditioning first:

1. Start parked. Sit with your dog in the parked car for a few minutes, with treats and praise.
2. Add short drives. Go around the block, then slowly longer, building up to 20 to 30 minutes over days or weeks. Stop for the day at the first sign of worry.
3. Time the meal. If it doesn't stress your dog, skip the meal for a few hours before the drive (VCA says up to 8 hours). Keep water available.
4. Secure your dog. A crate, carrier, booster seat or travel harness keeps them steady and safe. Get them used to it at home first.
5. Make the car calm. Keep it cool and quiet, bring a blanket that smells of home, and save a special toy for car rides.
6. Take breaks. On longer trips, stop and let your dog walk and sniff, especially if the drooling or lip licking starts.

Meclizine vs Cerenia for Car Sickness

Cerenia (maropitant) is the vet-prescribed alternative. The Merck Veterinary Manual calls it FDA-approved and the preferred drug for motion sickness in dogs.

Veterinary Partner suggests maropitant for dogs that don't tolerate meclizine. Your vet can tell you which suits your dog.

Meclizine Side Effects in Dogs

Most dogs handle meclizine well. The side effects come mostly from its antihistamine and "anticholinergic" (drying) action:

• sleepiness, the most common one
• excitement or restlessness instead of sleepiness, in some dogs
• dry mouth, dry gums and dry eyes
• a faster heart rate
• trouble passing urine
• worsening of glaucoma, a pressure problem inside the eye

Call your vet if a side effect is strong, lasts, or worries you. Sources: Veterinary Partner, VCA Animal Hospitals.

Which dogs should not take meclizine?

Your vet will be cautious, or choose something else, if your dog:

• has reacted to meclizine before
• has glaucoma
• has trouble urinating, an enlarged prostate, a bladder or bowel blockage, or spinal disease that affects urination
• has heart disease, heart failure or high blood pressure
• has a seizure disorder or an overactive thyroid (PetPlace lists both)
• has liver disease, which can make the drug last longer
• is pregnant (meclizine caused birth defects in lab animals) or nursing (it can reduce milk)
• is a puppy under 6 months
• has allergy skin testing coming up (VCA advises stopping meclizine 3 to 7 days before)

Sources: Veterinary Partner, VCA Animal Hospitals, PetPlace, PetMD.

Meclizine also interacts with other drugs, so tell your vet about every medicine and supplement your dog takes. Veterinary Partner flags:

• other sedating drugs, including other antihistamines, opioids and benzodiazepines such as diazepam or alprazolam
• other anticholinergic drugs, such as oxybutynin or scopolamine
• fluoxetine, which may keep meclizine in the body longer
• metoclopramide and cisapride, which meclizine may weaken

What If My Dog Took Too Much Meclizine?

Antihistamine overdoses can turn serious. According to the Merck Veterinary Manual and PetMD, signs can include:

• heavy sleepiness, or the opposite: agitation and overexcitement
• vomiting
• a fast heart rate, low blood pressure, dilated pupils
• tremors or seizures
• being unable to pass urine

Call now if your dog got into the bottle or took more than prescribed: your vet, the ASPCA Animal Poison Control Center at (888) 426-4435, or the Pet Poison Helpline at (855) 764-7661. Both are open 24/7 and may charge a fee. Have the package in hand so they know exactly what was swallowed.

Don't make your dog vomit unless a vet tells you to. Signs from these antihistamines can come on quickly, and the Merck Veterinary Manual says inducing vomiting is not appropriate for most animals that swallowed one. Merck's table notes signs may appear within 9 hours, so a dog that seems fine right away still needs that call.

Meclizine for Vestibular Disease in Dogs

The vestibular system keeps a dog balanced. It has parts in the inner ear (peripheral) and in the brain (central). When it goes wrong, the dog's world spins. Signs usually come on suddenly, according to VCA:

• a head tilt, one ear held lower than the other
• loss of balance, leaning, falling or circling to one side
• nystagmus: eyes flicking side to side or rolling
• nausea, vomiting, not wanting to eat
• not wanting to stand or walk

Causes include middle or inner ear infections, injury, tumors, an underactive thyroid and some ear-damaging drugs. When no cause is found it's called idiopathic vestibular syndrome, often nicknamed old dog vestibular disease because it's usually seen in older dogs. In a 2020 study of 188 dogs with peripheral vestibular disease, 68% had the idiopathic form and 26% had a middle or inner ear infection.

Inner ear or brain? Your vet's exam tells them apart. Trouble placing the feet, dullness, problems with other cranial nerves and up-and-down eye movements point to the brain, according to a 2020 study in the Journal of Veterinary Internal Medicine. Tests can include blood and urine tests, blood pressure, an ear exam, X-rays, and an MRI or CT scan.

Treatment depends on the cause. Anti-nausea and motion-sickness drugs like meclizine can ease the dizziness and vomiting while the dog recovers, and dogs that can't stand, eat or drink may need hospital care and IV fluids.

Signs are usually worst in the first 24 to 48 hours, many dogs improve within 72 hours, and most recover within two to three weeks, according to VCA. A head tilt can linger: in the 2020 study, about half of the dogs still had some deficit at follow-up, and about 1 in 6 had another episode.

See your vet the same day for any sudden head tilt, circling or loss of balance, so other causes, such as a stroke, can be ruled out. Call now if your dog can't stand, keeps vomiting, seems dull or confused, or gets worse instead of better.

Can Cats Take Meclizine?

Not for car sickness. Cats have no histamine receptors in the brain's vomiting trigger zone, so the Merck Veterinary Manual says antihistamines don't work for motion sickness in cats. Vets sometimes use meclizine in cats for other reasons, so ask your vet rather than using this chart.

Originally written by Dr. Kaylee Ferreira. Updated by the I Love Veterinary editorial team.

Sources

• Merck Veterinary Manual: Motion Sickness in Animals
• Merck Veterinary Manual: Table, First-Generation Antihistamines
• Merck Veterinary Manual: Toxicoses From Human Cold and Allergy Medications
• Merck Veterinary Manual: Drugs Used to Control or Stimulate Vomiting in Monogastric Animals
• Merck Veterinary Manual: The Neurologic Examination of Animals
• Merck Veterinary Manual: Xylitol Toxicosis in Dogs
• Veterinary Partner (VIN): Meclizine Hydrochloride
• VCA Animal Hospitals: Meclizine
• VCA Animal Hospitals: Motion Sickness in Dogs
• VCA Animal Hospitals: Vestibular Disease in Dogs
• PetMD: Meclizine (NausX) for Dogs and Cats
• PetPlace: Meclizine (Bonine, Antivert) for Cats and Dogs
• Orlandi R et al. Clinical signs, MRI findings and outcome in dogs with peripheral vestibular disease. BMC Vet Res. 2020;16:159
• Radulescu SM et al. Vestibular disease in dogs under UK primary veterinary care. J Vet Intern Med. 2020;34(5):1993-2004
• DailyMed: Dramamine Less Drowsy (meclizine) label
• DailyMed: Dramamine Original Formula (dimenhydrinate) label and Dramamine for Kids (dimenhydrinate) label
• DailyMed: Dramamine Chewable Orange, meclizine version and dimenhydrinate version
• DailyMed: Bonine (meclizine) chewable label, Bonine Max and Bonine for Kids (cyclizine)
• ASPCA Animal Poison Control Center
• Pet Poison Helpline

This article is for general information and is not a substitute for advice from your veterinarian.