Over-the-counter drugs your vet may recommend for your dog.

15 Over-the-Counter Human Drugs Your Vet May Prescribe for Your Dog

Remember: Never give any medication to your dog without approval from your veterinarian.

Some human drugs are dangerous and can even be fatal when given to dogs. Yet, when a dog develops a health problem at home, such as vomiting, diarrhea, or coughing, many pet owners want to know which human medications they can safely give to their pups.

Over-the-counter (OTC) drugs are those obtained without a prescription, many of which you’ll find in your medicine cabinet or occupying the shelves of your local Wal-Mart®, Walgreens®, CVS®, Target®, and/or online pharmacies and drug stores. One thing to keep in mind about OTC drugs is that they’re off label for pets, as they have not been approved for use on animals by the FDA.

Below, we will provide information about 15 over-the-counter human medications that many pet owners ask about giving to their dogs.

We will include information about stomach medications used for vomiting, drugs to treat diarrhea, drugs that can be used to treat allergies, and medications for car sickness.

Keep in mind though, it is always recommended that you work with your family veterinarian before giving any medication to your dog. If you're concerned about costs related to medication, pet insurance may be able to help. Click here to learn more.

Human OTC Stomach Medications Often Used in Dogs

Famotidine (Pepcid®)

Famotidine, commonly known by the brand name Pepcid® among others, is a histamine H2 receptor antagonist that decreases the production of acid in the stomach. It is frequently used to treat stomach problems such as ulcerations and for pets with nausea or who are prone to vomiting.

Famotidine is the most commonly used in this class due to its improved mechanism of action and length of action. It has largely replaced previous generation drugs like Cimetidine and Ranitidine.

Famotidine is available in oral tablets. Common oral sizes include 10 mg, 20 mg, and 40 mg. A common OTC size is 10 mg. A common dosage for dogs is 0.25 mg per pound orally once to twice a day.

For example, a 10-pound dog would get 2.5 mg dose. A 20-pound dog would get 5 mg dose.

Here is more information on how to safely dose and use Famotidine in dogs.

Ranitidine (Zantac®)

Ranitidine, commonly known by the brand name Zantac among others, is a histamine H2 receptor antagonist that decreases the production of acid in the stomach. Like Famotidine, it is commonly used to treat stomach problems such as ulcerations.

Ranitidine is available in oral tablets. Common oral sizes include 75 mg, 150 mg, and 300 mg. A common dosage for dogs is 1 mg per pound orally once to twice a day. This is easier to dose for larger dogs, since its smallest pill size is 75 mg.

Cimetidine (Tagamet®)

Cimetidine, commonly known by the brand name Tagamet® among others, is the oldest common histamine H2 receptor antagonist drug that decreases the production of acid in the stomach. Cimetidine is less commonly used due to the development of new and better drugs in the class of histamine H2 receptor antagonist.

The risks associated with Cimetidine mostly revolve around its interaction with other drugs. It is better to choose a newer generation histamine H2 receptor antagonist, like Famotidine or Ranitidine, that does not have those same possible adverse effects from drug interactions.

Calcium Carbonate (Tums®)

Calcium carbonate, commonly known as Tums®, is an antacid and oral phosphate binder. It is commonly used as a calcium supplement in dogs with chronic hypocalcemia and to treat hyperphosphatemia associated with chronic renal (kidney) failure. Calcium carbonate can also be used as an oral antacid and for conditions such as esophagitis and/or gastroduodenal ulcerations. However, calcium carbonate is uncommonly prescribed as an antacid, as there are stronger and more effective antacids.

Omeprazole (Prilosec®)

Omeprazole, commonly known by the brand name Prilosec®, is used in the treatment and prevention of stomach (gastric) and intestinal ulcers in dogs and cats. Omeprazole belongs to a class of drugs called proton pump inhibitors and lasts about 24 hours.

The dose most commonly used in dogs is 0.25 mg per pound once a day. Common OTC dosage sizes 10 and 20 mg pill sizes.

Learn more about how to safely give omeprazole to your dog.

Esomeprazole (Nexium®)

Esomeprazole, commonly known by the brand name Nexium®, is used in the treatment and prevention of stomach (gastric) and intestinal ulcers in dogs and cats. Although it’s in the same class of drugs as Omeprazole, it is not as commonly used or recommended for dogs.

Human OTC Bowel Medications Often Used in Dogs

Loperamide (Imodium®)

Loperamide, commonly known as Imodium®, is a synthetic piperidine derivative, that is used to treat diarrhea in dogs. It works primarily by slowing the movement of the intestines and may also decrease intestinal secretions and enhance mucosal absorption.

It is best to use this over-the-counter medication under the guidance of your veterinarian. If your dog is showing concurrent vomiting, lethargy, or weakness, it is best to have your dog evaluated by a veterinarian.

The dose most commonly used in dogs is 1 mg per 20 lbs no more than once. If diarrhea continues, contact your vet immediately.

Psyllium (Metamucil®)

Psyllium is not recommended unless directed by a veterinarian, since it is specific to chronic large bowel diarrhea, and owners can’t tell the difference between large bowel diarrhea and small bowel diarrhea.

It can be used for constipation, but there is an underlying reason a dog is constipated and that needs to be diagnosed by a veterinarian.

Simethicone (Gas-X®)

Simethicone, commonly known as Gas-X, should not be used without veterinary direction.

Polyethylene Glycol 3350 (MiraLAX®)

Polyethylene Glycol 3350, commonly known as MiraLAX®, is used as a laxative to treat feline constipation. It commonly comes as a powder you can mix with water or sprinkle on your cat’s food. MiraLAX® is also used to empty the intestines prior to diagnostic procedures, such as a colonoscopy or intestinal surgery in humans.

MiraLAX® is not recommended for dogs.

Bismuth Subsalicylate (Pepto-Bismol®, Kaopectate®)

Bismuth subsalicylate, better known as Pepto-Bismol, is used in humans to treat diarrhea and minor stomach problems, such as stomach inflammation. Both Pepto-Bismol and Kaopectate contain salicylate, which is related to aspirin. Dogs are sensitive to aspirin, and it should not be given with other medications like steroids (such as Prednisone and Dexamethasone) or non-steroidal anti-inflammatory (NSAID) drugs (such as Rimadyl, Novox, Meloxicam, Deramaxx, and many others). Please use only under the advice of your veterinarian and, if your dog vomits after being administered either of these drugs, take them to the vet immediately.

Learn more about bismuth subsalicylate here.

IMPORTANT WARNING: Bismuth Subsalicylate should never be used in cats.


Culturelle is a probiotic used in humans to combat diarrhea, constipation, or gas. It is not recommended for use in dogs.

Bisacodyl (Dulcolax®)

Bisacodyl is commonly known as Dulcolax® and is used as a laxative to treat constipation in humans. It is used to prep for a colonoscopy in dogs and cats, but is not recommended for home use.

Docusate Sodium (Colace®)

Docusate sodium is commonly known as Colace® and is used as a laxative to treat constipation in humans. Though it can be used as a stool softener for both dogs and cats, it is not commonly recommended by veterinarians.

Allergy Medications

Diphenhydramine (Benadryl®)

Diphenhydramine, commonly known by the brand name Benadryl® among others, belongs to a class or drugs known as antihistamines. Diphenhydramine is routinely used in dogs to treat symptoms associated with allergies or allergic reactions. Signs of allergies in dogs often include minor itching, scratching, and licking of the skin. This product should not be used to treat anything more serious.

If your dog has an open lesion, swollen face (especially around the muzzle and eyes), or hives, they need immediate medical attention, since this could be a sign of a more serious condition or anaphylactic reaction.

Often, dogs with chronic allergies have secondary skin infections and Diphenhydramine can be used in conjunction with antibiotics and steroid medications to control clinical signs.

Although diphenhydramine is relatively safe, side effects may include sedation, lethargy, vomiting, diarrhea, and lack of appetite.

The most common dose of diphenhydramine in dogs is 1 mg per pound. Therefore, a 25-pound dog would get one 25 mg tablet and a 50-pound dog would get two 25 mg tablets. It also comes in a liquid formulation made for children which makes it easier to dose in smaller dogs.

When buying diphenhydramine, make sure “diphenhydramine” is the only ingredient, since it’s often mixed with other common cold medications that might be dangerous or toxic for your dog.