Ondansetron For Dogs: Dosage, Safety & More

Ondansetron for Dogs

Ondansetron for Dogs: Ondansetron is an anti-nausea medication used to prevent vomiting in dogs. It works by blocking serotonin, a chemical in the body that causes nausea and vomiting. Ondansetron comes as an injectable liquid or oral tablets and is often prescribed for dogs undergoing surgery, chemotherapy, or other treatments that frequently cause nausea.

Ondansetron for Dogs

Uses of Ondansetron for Dogs

Ondansetron is primarily used to treat nausea and vomiting in dogs. It works by blocking serotonin, a chemical that triggers nausea and vomiting.

1. Nausea from Medications

If your dog experiences nausea or vomiting from medications like chemotherapy drugs, ondansetron can provide relief. Vomiting is a common side effect of many medications, but ondansetron helps ensure your dog can continue treatment.

2. Post-Operative Nausea

Ondansetron is also used to prevent nausea after surgeries or medical procedures. Giving ondansetron before a procedure helps ensure your dog will not experience nausea or vomiting from the anesthesia or medications during recovery.

3. Motion Sickness

For dogs that experience motion sickness during travel, ondansetron can be given before the trip to prevent nausea and vomiting. The effects tend to last 4 to 6 hours, so another dose may be needed for long trips. Ondansetron comes in tablets, injectable solutions or oral solutions, allowing you to choose the easiest method of administration for your situation.

4. Dosage and Safety

The typical dosage of ondansetron for dogs is 0.1 to 0.5 mg per pound of body weight, given by mouth 2-3 times a day. Ondansetron is usually well tolerated by dogs, but possible side effects include lethargy, diarrhea, and changes in liver enzyme levels. Ondansetron should not be used in dogs with liver disease or electrolyte imbalances. As with any medication, follow your vet’s dosage instructions carefully and watch your dog for any negative reactions.

See also  Simplicef for Dogs: Uses and Side Effects

Used properly, ondansetron is very effective at controlling nausea and allowing your dog to continue necessary treatments. By managing this side effect, ondansetron helps provide the best care and quality of life for your canine companion.

Ondansetron Dosage for Dogs

For nausea and vomiting in dogs, ondansetron is typically given orally in the form of tablets or oral solution (liquid). The dosage is based on your dog’s weight. The usual dosage range is between 0.1 to 0.5 milligrams per pound (0.2 to 1.1 mg/kg) given 2-3 times a day.


For tablets, a typical dosage for a small dog (up to 15 pounds) is 1 mg, for a medium dog (16 to 30 pounds) is 2 mg, for a large dog (31 to 60 pounds) is 4 mg, and for an extra-large dog (over 60 pounds) is 8 mg. The tablets should be given with food to increase absorption.

Oral Solution

The oral solution typically comes as a syrup with a concentration of 0.5 mg/mL. A small dog would get about 0.2 to 0.4 mL (0.1 to 0.2 mg) 2-3 times daily. For a medium to large dog, the dosage would be 0.5 to 2 mL (0.25 to 1 mg) 2-3 times daily. Use a syringe to carefully measure out the correct amount. The solution can be mixed in with some canned dog food or wet treat to make it more palatable.

Be very careful not to overdose your dog with ondansetron. While relatively safe, too high a dose can cause severe side effects like seizures, abnormal heart rhythm, and low blood pressure. Always double check the dosage recommended for your dog’s weight and follow your vet’s instructions carefully. Ondansetron can also interact with some other medications, so tell your vet about any other drugs your dog is on.

With the proper dosage and administration, ondansetron is very effective at relieving nausea and vomiting in dogs. However, if your dog’s symptoms do not improve, or get worse, contact your vet right away for further advice and evaluation. They may need to switch or combine anti-nausea medications to get the problem under control.

See also  The Best Dog Training in Rochester NY

Potential Side Effects of Ondansetron in Dogs

When given at the proper dosage, ondansetron is generally well tolerated in dogs. However, some potential side effects may occur, ranging from mild to severe. It’s important to monitor your dog after administration to ensure no adverse reactions.

1. Reduced Appetite

Ondansetron can temporarily reduce a dog’s appetite or interest in food. This is usually mild, but if your dog shows no interest in eating for over 24 hours, contact your vet. They may recommend discontinuing the medication or switching to an alternative.

2. Lethargy or Sedation

Some dogs may experience drowsiness, lethargy or sedation after taking ondansetron. This is usually temporary, but can be problematic if your dog seems overly sedated or has trouble walking steadily. Again, consult your vet right away if you notice these severe side effects.

3. Diarrhea or Constipation

Gastrointestinal upset, like diarrhea, constipation or vomiting may occur in a small percentage of dogs. The good news is these side effects are often transient, especially if the medication is only used short-term. However, prolonged or severe symptoms require a call to your vet.

4. Arrhythmias

Rarely, ondansetron can cause abnormal heart rhythms or rates in some dogs. This is more likely at higher doses or when given intravenously. Your vet will monitor your dog closely if ondansetron is given through an IV. Seek emergency care immediately if your dog shows symptoms like collapse, weakness or pale gums.

Ondansetron is a very safe medication when used properly under veterinary guidance. However, as with any drug, side effects can occur in some animals. By knowing the potential side effects to watch for, you can get your dog the help they need right away. Always consult your vet with any concerns about your dog’s reaction to this medication.

See also  Sucralfate for Dogs: A Gastric Ulcer Treatment That Works

READ ALSO: Piroxicam for Dogs: Dosage, Side Effects, and More


Is Ondansetron safe for dogs?

Ondansetron is generally very safe for dogs when used as prescribed by a vet. It has been approved for use in dogs and cats and has been widely used for years with few reported side effects. However, as with any medication, side effects are possible. The most common are drowsiness, diarrhea, and constipation. More serious but rare side effects include severe allergic reactions. Always follow your vet’s dosage instructions carefully and watch your dog for any unusual symptoms after giving the medication.

How long does it take for Ondansetron to start working?

Ondansetron begins working within 15 to 30 minutes after administration for most dogs. The effects typically last 4 to 6 hours. If your dog needs relief from nausea for a longer period, your vet may prescribe multiple doses to be given throughout the day. The medication may need to be re-administered for a few days until the underlying cause of the nausea and vomiting has been addressed.

Can I give Ondansetron with food?

Ondansetron can be given with or without food. However, giving it with a small amount of food, especially fatty food, may help increase absorption. If your dog is actively vomiting, you can give Ondansetron without food to provide faster relief. Once the vomiting is under control and your dog is keeping food down, give subsequent doses with meals or a treat to maximize effectiveness. Always follow your vet’s specific recommendations for your dog’s situation.

What if I miss a dose of Ondansetron?

If you miss a dose of Ondansetron, give it as soon as you remember, but do not double up on doses. Simply resume the regular dosing schedule. However, if it is close to the time for the next dose, skip the missed dose and go back to the regular schedule. Do not give an extra dose to make up for the missed one.

Providing Ondansetron as directed by your vet should help relieve your dog’s nausea and vomiting, allowing them to feel better faster. Be sure to contact your vet if symptoms do not improve, or if you have any other concerns about your dog’s condition or treatment.