Trazodone for Dogs: Dosage Chart, Uses and Side Effects

Trazodone is a human antidepressant that vets prescribe to take the edge off a dog's fear: before a vet visit or grooming, during storms, fireworks or car trips, and to keep a dog calm through weeks of crate rest after surgery. Some dogs also take it every day for ongoing anxiety, usually alongside another behavior medicine and a training plan. It isn't approved for animals, so your vet decides whether to use it and sets the dose for your dog's weight, health and situation.

One rule matters more than any number on this page: never add tramadol, an antidepressant or any other new medicine to trazodone on your own. Some combinations can trigger serotonin syndrome, a rare but dangerous reaction.

What Is Trazodone and How Does It Work in Dogs?

Trazodone was developed to treat depression in people. In dogs it is an extra-label drug: there is no FDA-approved animal version, but vets can legally prescribe the human tablets, or a version made by a compounding pharmacy. That is common, but it means there is no pet label to follow. The dose, timing and form are your vet's call.

In more than 32 million US dog records from 2010 to 2020, trazodone was prescribed far more often than fluoxetine or clomipramine, the two other behavior drugs the researchers tracked.

How it works: trazodone is a serotonin antagonist and reuptake inhibitor. Serotonin is a chemical messenger that helps regulate mood. Trazodone mainly blocks one type of serotonin receptor (5-HT2A) and, to a lesser degree, slows serotonin's recycling. In dogs the result is calmer behavior and often mild sleepiness. It is also why mixing it with other serotonin-raising drugs needs care.

What Vets Use Trazodone For

Vets use trazodone in three main ways, with different doses and timing.

Situational use: one dose before something scary

The dog gets trazodone ahead of a predictable stressful event, then nothing until the next one. Merck Veterinary Manual groups it with the "situational" medicines that act quickly and wear off quickly.

• Vet visits and grooming. In a 2022 placebo-controlled trial of 20 dogs with a history of vet-visit anxiety, owners rated dogs on trazodone as less stressed during the exam. Not every measure improved: stress hormone levels didn't change.
• Storms, fireworks and car trips. If your dog trembles during storms, our guide to why dogs shake covers the other causes your vet will want to rule out.
• Hospital stays. In an Ohio State study of 120 hospitalized dogs, those on trazodone showed less lip licking, panting and whining.

For event fear, your vet may instead choose gabapentin, another situational drug.

Crate rest after surgery

In a 2014 study of 36 dogs after orthopedic surgery, owners gave trazodone, mostly twice a day, for at least 4 weeks, and about 89% rated it moderately or extremely helpful for keeping their dog calm and confined.

Daily use for ongoing anxiety

Some dogs with separation anxiety, other anxiety disorders, fear aggression or compulsive behavior take trazodone every day, usually as an add-on: in a study of 56 dogs at a referral behavior clinic, it was added when other behavior drugs weren't enough and was well tolerated. One common approach is a daily "baseline" medicine such as fluoxetine, with trazodone for the hardest moments. Merck is clear that medication works best alongside behavior modification, not instead of it.

Trazodone Dosage Chart for Dogs

Every use below is extra-label, and published sources don't all agree, so where they differ we show both.

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.

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

Call now if your dog got more than prescribed, is very wobbly, very hard to wake, or shows any sign of serotonin syndrome (see below): call your vet, the ASPCA Animal Poison Control Center at (888) 426-4435, or the Pet Poison Helpline at (855) 764-7661. A consultation fee may apply.

What the chart can't show:

• Upper limits. Merck lists no more than 19.5 mg/kg (8.9 mg/lb) in 24 hours. A published limit from Gruen and Sherman 2008, as cited in Gilbert-Gregory 2016, is no more than 300 mg in one dose or 600 mg in 24 hours, and the calculator caps each dose at 300 mg.
• Big dogs hit that ceiling fast. For a 30 kg (66 lb) dog, 12 mg/kg would be 360 mg, above the 300 mg single-dose limit. One more reason the number should come from your vet.
• Vets usually start low. Veterinary behaviorists writing in Clinician's Brief generally start at 2 to 3 mg/kg and adjust to how the dog responds. The mg/lb figures are converted from the per-kg doses.

How to Give Trazodone to Your Dog

• Do a test dose first. When trazodone is new, specialists advise a test dose at home on a calm day with nothing scary planned. Note how long it takes to work, how long it lasts and any side effects, and tell your vet before the real event.
• Time it. For a planned event, give it 1 to 2 hours beforehand, or as your vet directs.
• Forms. Human trazodone comes as scored tablets (50, 100, 150 and 300 mg), so your vet can prescribe part of a tablet. They may also prescribe a compounded version when a dog needs a strength or form the tablets don't come in.
• Missed a dose? Call your vet's office. Usually you give it when you remember, or skip it if the next dose is close. Never give a double dose.
• Check the bottle. Trazodone and tramadol look alike on labels, and some dogs go home with both after surgery.
• Storage. Room temperature, 68 to 77°F (20 to 25°C), in a closed container away from light and moisture, out of reach of children and pets. If a person swallows it, call Poison Control at 800-222-1222.

Before a vet visit: a simple plan

1. Ask your vet ahead of time whether a pre-visit medicine makes sense for your dog.
2. Do the test dose at home on a calm day before the visit.
3. On the day, give it at the time your vet set. In the 2022 trial, dogs got it 90 minutes before the car ride.
4. Tell the clinic team your dog had trazodone, and tell your vet afterwards how it went.

Some clinics also train their teams in low-stress handling; see our article on Fear Free certification.

How Long Does Trazodone Take to Work and How Long Does It Last?

For a one-off dose, trazodone usually starts working within 1 to 2 hours (a median of 31 to 45 minutes in the post-surgery study). Effects usually last several hours (sources range from about 4 to 12). For daily use, the full benefit can take a few weeks. Timing also varies between dogs (in a study of six Beagles, blood levels peaked at very different times), which is exactly why the test dose is worth doing.

Side Effects of Trazodone in Dogs

Trazodone is generally well tolerated in the published dog studies, and most side effects are mild.

• Common: sleepiness, a "spacey" look, wobbliness (ataxia), vomiting, diarrhea or nausea.
• Less common: restlessness, more anxiety instead of less, aggression, a faster heart rate.
• Rare: liver injury and priapism (a persistent, painful erection) have been reported.

In the 36-dog post-surgery study, owners reported at least one side effect in 20 dogs, most often looking "drugged" or "spacey" (5 dogs), and no dog had to stop because of them.

Sedation can also hide pain, so tell your vet if your dog seems sore or "not right" while on it. And in a small number of dogs trazodone lowers their inhibitions instead of calming them: in the Ohio State hospital study, one dog was taken off it because of aggression. If your dog becomes more aggressive or fearful on it, call your vet before the next dose.

When to call:

• Mention at your next visit: mild sleepiness or wobbliness that wears off before the next dose.
• See your vet soon: your dog seems sedated or unsteady day after day, keeps vomiting or has diarrhea, eats less, becomes more anxious or snappy, or the medicine doesn't seem to help.
• Call now: your dog got more than prescribed, cannot stand or is very hard to wake, has a persistent erection, or shows signs of serotonin syndrome or an allergic reaction (facial swelling, hives, trouble breathing). Call your vet, the ASPCA Animal Poison Control Center or the Pet Poison Helpline (numbers above).

Serotonin Syndrome and Drug Interactions

Serotonin syndrome happens when too much serotonin activity builds up in the nervous system. With trazodone it is rare, and the risk mostly comes from combining it with other serotonin-raising drugs.

Signs to watch for: vomiting or diarrhea, disorientation, vocalizing, drooling, dilated pupils, tremors, a racing heart, trouble breathing, weakness or wobbliness, seizures. Any of these after a new medicine or a dose change = call now. Vets treat it in the hospital, sometimes with a serotonin-blocking drug called cyproheptadine.

Tell your vet about everything your dog gets, including supplements, herbal products and CBD.

Never combine trazodone with MAOI drugs such as selegiline, or give it within 4 weeks of stopping one.

Only if your vet plans it:

• Fluoxetine, clomipramine and other antidepressants. Vets combine these with trazodone on purpose, and veterinary behaviorists consider that generally safe at appropriate doses. The danger is adding one yourself, including a family member's prescription.
• Tramadol. Often prescribed with trazodone after surgery. In the crate-rest study, trazodone started at half the later dose while dogs were on tramadol, because tramadol also raises serotonin.
• Other medicines listed as interactions include mirtazapine, the anti-nausea drugs metoclopramide and ondansetron, and some antibiotics and antifungals such as ketoconazole that slow how the body clears trazodone.
• Pain relievers. In people, trazodone can add to the bleeding risk of aspirin and NSAIDs; in the dog post-surgery study it was well tolerated alongside NSAIDs.

Dogs That Need Extra Care

Trazodone is used with caution, or not at all, in dogs that:

• have had a reaction to trazodone before;
• have heart disease, liver disease or kidney disease;
• have angle-closure glaucoma;
• are working or assistance dogs, since sleepiness can dull their focus.

Before starting any behavior medicine, Merck advises vets to rule out medical causes, often with blood and urine tests.

Stopping Trazodone

If your dog only gets trazodone now and then before events, there is no ongoing course to stop: you simply don't give it next time.

If your dog takes it every day, especially alongside other behavior medicines, ask your vet before stopping. Withdrawal effects haven't been reliably shown in dogs, according to veterinary behaviorists, but the human label advises reducing the dose gradually rather than stopping abruptly whenever possible, and stopping one drug in a combination changes the whole plan. Your vet will tell you whether to step the dose down.

Alternatives and Add-ons to Trazodone

Medicine works best as one part of a plan. Your vet may suggest:

• Behavior modification, ideally with a veterinary behaviorist or qualified trainer.
• A calmer home during scary events: a safe retreat spot, white noise during storms, puzzle toys for distraction. Some owners also try a pressure wrap; see our review of Thundershirts for dogs.

Thinking about CBD or another calming supplement? Tell your vet first.

Quick Answers

Can puppies take trazodone? Whether a puppy should take it, and how much, is your vet's decision.

Can I give my dog my own trazodone? No. The strength may be wrong, and your vet needs to check your dog's other medicines first.

What if my dog ate a whole bottle? Treat it as an emergency and call your vet or a poison line now. Overdose can cause heavy sedation, wobbliness and vomiting, and serotonin syndrome if other serotonin drugs are involved.

Summary

Trazodone helps many dogs through vet visits, storms and crate rest, with sleepiness, wobbliness and an upset stomach as the usual trade-offs. Use the chart to understand what your vet prescribed, not to choose a dose yourself. Do a test dose before the big day, never add tramadol or an antidepressant on your own, and call right away if your dog can't stand, is hard to wake or shows signs of serotonin syndrome.

Originally written by Dr. Catharina Hjorth. Updated by the I Love Veterinary editorial team.

Sources

• Merck Veterinary Manual: Common Drugs Used to Treat Behavior Problems in Dogs
• Merck Veterinary Manual: Treatment of Behavioral Problems
• Gruen ME et al. (2014): The Use of Trazodone to Facilitate Post-Surgical Confinement in Dogs (JAVMA)
• Gilbert-Gregory SE et al. (2016): Effects of trazodone on behavioral signs of stress in hospitalized dogs (JAVMA; also cites the Gruen and Sherman 2008 and Herron and Shreyer 2014 dose ranges)
• Gruen ME, Sherman BL (2008): Use of trazodone as an adjunctive agent in the treatment of canine anxiety disorders: 56 cases (JAVMA)
• Kim SA et al. (2022): Effects of trazodone on behavioral and physiological signs of stress in dogs during veterinary visits (JAVMA)
• Jay AR et al. (2013): Pharmacokinetics, bioavailability, and hemodynamic effects of trazodone in dogs (American Journal of Veterinary Research)
• Weng HY et al. (2025): Real-world data on behavioral practices for dogs in US primary care veterinary hospitals (JAVMA)
• Clinician's Brief: Trazodone for Dogs and Cats: Indications, Dosage, and Effects
• PetMD: Trazodone for Dogs
• MedVet: Trazodone for Dogs, A Guide for Pet Owners
• U.S. National Library of Medicine, DailyMed: Trazodone hydrochloride tablets (human prescribing information)
• ASPCA Animal Poison Control Center

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