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Can My Dog Take Phenergan? 6 Safe Uses for Pets

Medically reviewed by Dr. Erica Irish, DVM

Going on a road trip with your dog?

Unfortunately, not every dog loves a car ride. Some dogs are just too anxious, and others experience travel sickness.

Luckily, there are many options out there to help solve these problems.

Anti-anxiety medications with sedative properties can help make the trip a more pleasant experience for everyone.

Keep reading for suggestions on alternatives for long-term anxiety issues in dogs.

You may have heard people talk about Phenergan for dogs. It’s possible you even have some in your medicine cabinet.

No matter what anybody says, it’s not a good idea to give it to your dog without a medical consultation.

Vet Approval

Dogs can safely take Phenergan with a veterinarian’s approval. This medication can be used to help dogs with things like anxiety or motion sickness, but it’s not designed to be used long-term.

Promethazine (available under the following different brand names: Phenergan, and Phenadoz) is a first-generation antihistamine used to treat a variety of allergy symptoms in people.

Information Pet Owners Should Know

In this post, you’ll discover more about the product including which dogs are good candidates for it.

Learn more about the differences between Phenergan and other antihistamines along with common side-effects.

We’ll provide guidelines for appropriate dosing, and why it matters whether a veterinarian sees your dog before administering this drug.

What is Phenergan?

Phenergan is a first-generation antihistamine. First-generation antihistamines work by binding to histamine receptors in the brain and spinal cord. These are known for their sedating properties.

This blocks histamines from binding to histamine receptors, the substance responsible for causing allergy symptoms in the first place.

Phenergan (promethazine) is a common human medication used to treat allergy symptoms in humans, including:

  • runny nose
  • nausea
  • vomiting
  • motion sickness
  • pre-and post-operative sedative.

In dogs, this medication is used “off-label” by veterinarians to treat things like motion sickness in dogs. It can also be used short-term for anxiety, sedation, and to treat atopic dermatitis.

Off-label simply means that the drug isn’t being used for its original intention.

Although approved for human use for allergy symptoms, this drug has been shown to be beneficial for dogs under certain circumstances.

Phenergan infographic.

Supplements for Long-Term Anxiety Issues

The market is saturated with a variety of products designed to aid dogs with anxiety issues. Most are safe for otherwise healthy dogs. However, some ingredients like St. John’s Wort can actively interfere with prescriptions.

Interactions can be serious so it’s always important to talk to your veterinarian about anti-anxiety supplementation. This is especially true if your dog is on a prescribed medication.

A Few Recommendations for Anxiety Issues in Dogs

It can’t be stated enough…. always check with a veterinarian before providing supplements to your dog. This is especially true for dogs with other prescriptions and underlying conditions.

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Histamine versus Allergies in Dogs – The Reason for Those Nasty Reactions

Histamine is a natural substance in the body. If you are having an allergic reaction to something, the body’s natural instinct is to want to get rid of the cause.

For people or dogs with allergies, the immune system goes into overdrive. Histamine is one of many inflammatory

Histamine attaches to cells and foreign bodies, marking them like a flag telling them how to be dealt with.

 It tells the stomach cells to produce acid and even keeps the brain alert. Under normal (healthy) circumstances, histamine goes unnoticed. It does what it is supposed to do without causing any distress.

Dogs (or people) with allergies have a different response. In that case, the body’s immune system overreacts to normal things that are normally safe.

Environmental allergies are common triggers in dogs. These can include allergies to:

  • dust mites
  • pollen
  • mold

If histamine is completely out of control, it can lead to anaphylaxis.

Anaphylaxis is a dangerous condition that needs immediate attention. It causes the throat to close up and cut off breathing. A sudden drop in blood pressure could deprive vital organs of oxygen.

If you’re interested in the details of how histamine works in the body, check out this publication on antihistamines.

Why is Phenergan Prescribed for in Dogs?

Phenergan has a variety of uses in dogs. Does your dog get motion sickness and vomit during car rides? If so, Phenergan might be prescribed to help.

That said, it’s important to note that vets are not recommending antihistamines/sedatives for anxiety as often as they used to, at least with respect to Phenergan and Benadryl.

Yes, a dog might be sleepy and sedate, but the meds do not address the actual anxiety.

In the Past, Vets May Have Prescribed Phenergan for:

1. Pre or Post-Surgical Sedation

In some cases, Phenergan may be administered to help sedate a dog before surgery. It can also be useful in easing pain and discomfort after surgery.

2. Itchy Skin/Allergic Reactions

Itchy skin in dogs can be caused by a number of things. Under the guidance of a licensed veterinarian, this medication can help to ease symptoms of itchy skin.

Allergies are one thing, but it’s always a good idea for a veterinarian to diagnose before administering this medication.

Itchy skin could be caused by allergies, but it could also be caused by mast cell tumors, underlying infection, or any number of secondary diseases.

Administering this medication under conditions like these may alleviate the symptoms. However, it won’t address the main problem and that can lead to serious consequences.

3. Nausea and Motion Sickness

It’s not unusual for some puppies to develop nausea and vomiting during car rides. In most cases, dogs outgrow that phase as their bodies mature.

Normally, pet owners would try to avoid situations that leave their dogs feeling sick or uncomfortable. However, that’s not always possible. If you need to travel with your dog, Phenergan may be the solution.

In addition to working as an antihistamine, Phenergan is also considered a weak antiemetic.

Antiemetic medications work by controlling the need to vomit. Better drugs might include maropitant and ondansetron, but Phenergan may help a little.

4. Anxiety

Anxiety is common in dogs, especially when it comes to the two main triggers: Thunderstorms and fireworks. In certain situations, a short-term “solution” like Phenergan may help.

Separation anxiety and other behavioral issues may respond better to other things. This could include a mild natural sedative along with behavioral training.

Phenergan isn’t usually the first choice for any of the above circumstances. It takes a licensed veterinarian to evaluate your dog for underlying conditions before prescribing this medication.

Gabapentin is commonly prescribed for short-term anxiety relief.

5. Hypersensitivity  Disorders

Food, environmental, and contact allergies fall under the hypersensitivity umbrella.

While the medication can help ease the symptoms associated with an allergy, (food allergies, itchy skin, etc.) the goal should be to narrow down and eliminate the cause of the allergy.

6. Travel

Most forms of travel with the dog involve a short ride in the car.

However, there may be times when you need to fly, and your dog needs to go with you. Airlines all have different guidelines, but large dogs are expected to ride in the cargo hold.

Small dogs that can fit into a carrier that fits under the seat in front of you are usually allowed with you.

Airlines expect your dog to be securely crated in a single metal door kennel. The goal is to have your dog safely in a crate that won’t collapse in on itself.

Dogs are safe travelling this way, but they don’t know that. Having your dog sedated for as much of the flight is possible with the right medication. Again, this would be a conversation for the veterinarian.

Since Phenergan only has mild sedative properties, and only lasts for 6 – 8 hours, you may want something that lasts longer, especially for long flights.

Try these chemical free alternatives for dogs with anxiety:

Is Phenergan Safe for Dogs?

Phenergan can be used to safely treat allergy and motion sickness symptoms in dogs.

It should never be used on dogs with central nervous system disorders including vestibular disease or dogs with seizures.

The drug could interact with other medications and make balance disorders or dizziness much worse.

Vestibular disorders affect your dog’s sense of balance. For example, canine idiopathic vestibular disease or “Old Dog Vestibular Syndrome” is a sudden disturbance of balance.

This disorder is activated by issues affecting the dog’s inner ear and middle ear.

Ongoing conditions may require another prescription. Nothing really helps cure it, but medications like diazepam and meclizine can sometimes help symptoms.

Phenergan is a mild sedative safe for dogs infographic.

Ask a Vet Online for Less Than a Trip to A Clinic

Sometimes I share affiliate links with my readers if I think a product or service might be useful. If you click on a link below, you will be brought to that product’s homepage. If you decide to make a purchase, I may earn a small commission.

Ask a Vet is an online service that is available to anybody, worldwide. It’s a quick, inexpensive way to ask a licensed veterinarian your burning questions. They are not able to diagnose your pet online, but you’d be surprised how much useful information they can share with you.

Why sit around worrying or waiting for a vet appointment if you only have some questions to ask?

Check out Ask a Vet!

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A Word of Caution

Phenergan is considered safe for dogs when the appropriate dosage is administered.

The main concern with this drug is that pet parents may attempt to diagnose and administer the medication without medical intervention.

Unfortunately, not every animal is a good candidate. Underlying conditions like kidney disease, inappropriate dosing, and drug interactions can be dangerous.

Other Prescriptions Used for Allergies in Dogs

Tavist (Clemastine Fumarate)

Update: Tavist has been discontinued in the United States

Hydroxyzine (Atarax)

This antihistamine is available in small tablets. This makes them easier for a dog to swallow (or to hide in their food).

Atarax should not be given to pets with:

  • glaucoma
  • lung disease
  • heart disease
  • high blood pressure,
  • prostate enlargement.

Benadryl (diphenhydramine)

Benadryl is available over the counter in a variety of cold and allergy medications.

Some of these medications contain additives that may be harmful to your dog. Never give your dog a medication with more than one ingredient. The medication is taken every 8 hours and may cause drowsiness.

Common Side-Effects of Phenergan for Dogs

Side effects of Phenergan are thought to be minimal in small doses. However, it’s important to check with the pet’s veterinarian before administering. The veterinarian will be able to give you the best dosage for your dog. 

Side effects may include:

  • dry mouth
  • drowsiness
  • loss of appetite (rare)

Rare side effects could include a dangerous interaction with other prescription drugs, over-the-counter drugs, or even supplements. This is why it’s so important to tell the veterinarian about all the things your dog is taking.

Never give your dog Phenergan if he/she has been diagnosed with any type of central nervous disorder. 

If you have given this medication to your dog and are experiencing unusual side effects, please contact your veterinarian as soon as possible. Excessive dog Phenergan dosage can be dangerous.

Phenergan Dosage for Dogs

The typical promethazine dose for dogs is 0.2 mg to 0.4 mg.

It is critical to remember that the dose will vary depending on your dog’s weight and the severity of his symptoms. It is also important to remember that this medication can be dangerous if used incorrectly.

Always seek medical advice from a licensed veterinarian before administering any medication to your dog.

Dosages may vary depending on the size of your dog, dog’s age, and the presence of underlying conditions. Dogs with liver disease should not take Phenergan.


Human Phenergan is the same medication used in dogs occasionally. This prescription drug is considered safe but can cause serious drug interactions for dogs when used in combination with other prescriptions.

This short-term dog treatment can be used for things like seasonal allergies, hay fever, reactions to insect bites, etc. In dogs, Phenergan is useful as a sedating product and to ease motion sickness.

The best way to ensure safety for your dog is to speak with the dog’s veterinarian about the issues you’re having with your dog.


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