Stephanie Howe, DVM
By Stephanie Howe, DVM on Oct. 7, 2022

In This Article


PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What is Trazodone?

Trazodone is a human antidepressant that is commonly used in the veterinary field to treat certain behavior disorders in dogs and cats. While trazodone is FDA-approved for human use, it is currently not FDA approved as a veterinary medication. However, it is readily utilized in the veterinary field, and veterinarians can legally prescribe certain human drugs in animals in certain circumstances. This is called extra-label or off-label use because this use isn’t described on the drug label.


Trazodone may help calm dogs that suffer from separation anxiety or are triggered by stressful events such as fireworks or veterinarian visits. Your veterinarian may also prescribe trazodone for your dog after surgery, especially if recovery requires resting in a crate or other confined space. It can be used alone but is frequently used in combination with other anxiety medications.


In certain circumstances, your vet may recommend a compounded formulation of trazodone. Compounded medications are prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug. Compounded medications are not FDA-approved. They are created by either a veterinarian or a licensed pharmacist on an individual basis to best suit a patient’s particular needs. You can learn more about compounded medications here.

How Trazodone Works

Trazodone works by increasing serotonin levels in an animal’s central nervous system. Serotonin is a chemical messenger that works in the brain to regulate behavior and other bodily functions. Many common antidepressants, including selective serotonin reuptake inhibitors (SSRIs), also increase serotonin levels.

Trazodone Directions

Follow the directions on the drug label or as provided by your veterinarian. Your veterinarian will prescribe a dose based on your pet’s body weight and the reason for its use. Depending on your pet’s condition, your pet may need to take trazodone daily or only as needed for anxiety-provoking events (such as fireworks, thunderstorms, or veterinary visits).

Give trazodone as directed, usually at least 90 minutes before a triggering event. Consult your veterinarian if your pet’s condition has not improved after starting trazodone.

Missed a Dose?

If you forget to give a dose of trazodone, give it when you remember. However, if it is almost time for your next dose of the medication, skip the missed dose and resume your normal dosing schedule. Do not give extra or double doses.

Trazodone Possible Side Effects

Trazodone is well-tolerated by most pets. The most common side effects are related to the digestive system (vomiting, diarrhea, or nausea). Less common side effects may include the following: increased anxiety or agitation, aggression and increased heart rate may occur.

  • Trazodone is often given with other behavioral drugs. Serotonin syndrome is a rare but serious condition that can occur when these drugs are given together, especially in large doses. Seek immediate emergency care if signs of serotonin syndrome occur:

  • Vomiting or diarrhea

  • Seizures

  • Increased skin sensitivity (hyperesthesia)

  • Depression

  • Dilated pupils or blindness

  • Vocalizations (whining, crying)

  • Excessive drooling

  • Trouble breathing

  • Weakness or lack of coordination

  • Disorientation

Human Side Effects

While this is a human prescription medication there are different dosages and side effects that can occur in humans. If you accidentally ingest a pet medication, call your physician or the national Poison Control Center hotline at 800-222-1222.


No specific monitoring is required for this medication, but your veterinarian may recommend routine testing depending on your pets' individual needs, other medications they may be on and/or the issue that initially caused your pet to be placed on this medication.

Call Your Vet If:

  • Severe side effects are seen (see above)

  • You see or suspect an overdose

  • You have additional questions or concerns about the use of Trazodone

Trazodone Overdose Information

An overdosage of trazodone may cause sedation, decreased energy level (lethargy), lack of coordination, and vomiting. Overdosage of trazodone in combination with other medications or supplements that affect serotonin levels could result in a serious condition called serotonin syndrome (see above). Immediate emergency treatment may be necessary.

If you suspect an overdose, immediately contact your veterinarian or an animal poison control center. Consultation fees often apply.

Pet Poison Helpline (855) 764-7661

ASPCA Animal Poison Control (888) 426-4435

Trazodone Storage

Trazodone should be stored at controlled temperatures between 68-77 F and brief exposure to temperatures 59-86 F are acceptable. Keep the container tightly closed in order to protect from moisture and light.

Compounded medications should be stored according to the compounding pharmacy’s label.

Keep out of reach of children and pets.

Trazodone FAQs

How quickly does trazodone take effect in dogs?

When used only as needed, trazodone will typically take effect in 1-2 hours. When used daily, improvement in your pet’s behavioral condition may take a few weeks. However, you may notice gradual improvement before then.



Stephanie Howe, DVM


Stephanie Howe, DVM


Dr. Stephanie Howe graduated from the University of Florida College of Veterinary Medicine in 2011, after receiving a Bachelor of Science...

Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health