Trazodone for dogs is a human antidepressant that vets prescribe off-label to take the edge off fear and stress. It's often used before vet visits, during fireworks or on crate rest after surgery. Most dogs handle it well, and sleepiness or an upset stomach are the usual side effects. It's prescription-only because your vet has to set the dose and check it against your dog's other medications.
If your dog's stress is mild and predictable, like a restless night or a short car ride, there are over-the-counter options worth raising with your vet, such as our melatonin drops for dogs.
What trazodone is and why vets use it off-label
Trazodone is a SARI, short for serotonin antagonist and reuptake inhibitor. It changes how serotonin works in the brain, and in dogs that tends to show up as calmer, sleepier behaviour.
In the US, the FDA has approved it for people only. When a vet prescribes it for a dog there, that's called extra-label or off-label use, which just means the drug was made for humans and borrowed for dogs. In the Philippines it's prescription-only too, and your vet will prescribe it under local rules.
It's one of a handful of calming meds vets use for dogs. It can be given only when needed, or daily as part of a longer plan.
When to call your vet right away
Call your vet, or an emergency vet clinic after hours, if your dog shows any of these after a dose:
- A racing heart, muscle tremors or stiff, rigid muscles
- Heavy panting with agitation, restlessness or disorientation
- Seizures
- Collapse, deep sluggishness or pauses in breathing
- Sudden aggression that's out of character
- In males, an erection that won't go away (rare, but reported)
The first three can point to serotonin syndrome, a reaction to too much serotonin activity. VCA Animal Hospitals notes its signs can appear within one to two hours of a dose. The risk goes up when trazodone is mixed with other drugs that affect serotonin.
For a double dose or a raided pill bottle, contact your vet or an emergency vet clinic right away. Poison specialists at the US-based ASPCA say overdose signs usually start within 30 to 60 minutes and most often last 10 to 12 hours, though they can last more than a day.
What vets prescribe trazodone for
The Merck Veterinary Manual lists anxiety disorders, fear aggression, compulsive disorders, sedation for vet care and post-surgical confinement. In practice, vets use it for separation anxiety in dogs, noise phobias around thunderstorms and fireworks, travel and clinic visits. It's also common during crate rest after orthopaedic surgery.
It's often an add-on rather than the whole plan, and vets frequently pair it with a daily behaviour medication.
Trazodone dosage for dogs: the ranges vets publish
What vet references publish
Your vet sets the dose, based on your dog's weight, health and other medications. What we can show you is the range vet references publish, so the number on your label makes sense.
The Merck Veterinary Manual lists 2 to 7.5 mg per kilogram of body weight, given by mouth. That dose can be repeated every 8 to 24 hours as needed. Merck also caps the total at 19.5 mg/kg in any 24-hour period. Clinician's Brief gives a wider range, 2 to 12 mg/kg. Its authors usually start low, at 2 to 3 mg/kg.
If you know your dog's weight in pounds, 1 kg is about 2.2 lb.
What Merck's range works out to by weight (illustration only, not a dosing chart)
The table runs Merck's published mg/kg range through four common weights, rounded. It shows how wide the range is. Don't use it to dose your dog.
| Dog weight | Approx. weight in lb | Merck's mg/kg range applied to this weight (not a dose) |
|---|---|---|
| 4.5 kg | 10 lb | 9 to 34 mg |
| 11.3 kg | 25 lb | 23 to 85 mg |
| 22.7 kg | 50 lb | 45 to 170 mg |
| 36.3 kg | 80 lb | 73 to 272 mg |
For a dog of about 22.7 kg (50 lb), the top of that range is nearly four times the bottom. Other references publish different ranges again. That's why your vet sets the actual dose, usually starting at the low end and adjusting after you report back.
Immediate-release tablets come in several strengths, from 50 mg up to 300 mg. If your dog's dose doesn't line up with a whole tablet, ask your vet or pharmacist how to give it.
Is 300 mg of trazodone a lot for a dog?
It depends on the dog. Against the Merck range, 300 mg in one dose sits just above the top end for a dog of about 36.3 kg (80 lb). For a 4.5 kg (10 lb) dog, it's many times the published range. Whatever the label says, never change the dose yourself. If it seems too strong or too weak, report back rather than adjusting it.
How long trazodone takes to work and how long it lasts
Most dogs feel trazodone within one to two hours, according to VCA and PetMD. That's why vets usually ask you to give it at least 90 minutes before you leave. In one post-surgery study, owners noticed it kicking in at around 30 to 45 minutes.
How long it lasts is less tidy. Owners in that study reported effects of four hours or more. PetMD puts it at about 8 to 12 hours. VCA says this short-acting drug should stop working within a day, though dogs with liver or kidney disease can feel it longer.
| When | A vet-visit day on trazodone |
|---|---|
| A quiet day beforehand | Give a test dose at home and watch how your dog reacts |
| About 90 minutes to 2 hours before you leave | Give the dose exactly as your vet directed |
| 30 minutes to 2 hours after the dose | It kicks in, and your dog may look calmer, sleepier or a bit wobbly |
| The next several hours | Sleepy but still responsive, for roughly 4 to 12 hours depending on the source |
| Within 24 hours | It should have worn off, unless your dog has liver or kidney disease |
Clinician's Brief recommends a test dose at home on a calm day, so you don't first see your dog's reaction on appointment morning. The same goes for car-ride stress: try any new calming plan on a quiet weekend before the long drive.
You can give it with or without food, though VCA suggests a meal or small treat if your dog vomits on an empty stomach. With daily use, the full effect can take a few weeks.
Trazodone side effects most dogs actually have
Sedation is the side effect you're after, up to a point. A dog who naps through the afternoon or looks a little drunk on their feet is usually just feeling the drug do its job.
The common ones are sleepiness, vomiting, nausea, diarrhoea and wobbliness (vets call it ataxia). Less often, dogs get a faster heart rate or more anxiety rather than less. VCA also lists dilated pupils and a bigger appetite.
A few dogs have a paradoxical reaction and become agitated or even aggressive. In a 2016 hospital study, one dog turned aggressive about an hour after its dose, and it happened again when the dose was repeated. If your dog reacts this way, hold off on the next dose and report the reaction before giving more.
VCA advises against trazodone for dogs with angle-closure glaucoma or a known sensitivity to the drug. It also calls for care in dogs with severe heart disease, liver or kidney problems, and in pregnant dogs.
Drug interactions to tell your vet about
Tell your vet everything your dog takes, including supplements and flea and tick products. These matter most:
- MAO inhibitors, including selegiline and amitraz tick collars. They shouldn't be combined with trazodone, and sources disagree on how long to wait after stopping one, from 2 to 4 weeks.
- SSRIs such as fluoxetine, tricyclic antidepressants and tramadol for dogs. Vets do combine some of these with trazodone, but only under close supervision, because the mix raises the risk of serotonin syndrome.
- Azole antifungals and macrolide antibiotics, which can strengthen trazodone's effects.
- Other sedatives, including acepromazine.
- Aspirin and NSAIDs like meloxicam, which are on VCA's interaction list.
- Some blood pressure and stomach medications, including diuretics, ondansetron and metoclopramide.
VCA's behaviour specialists point out that interactions can happen even with non-prescription products. So ask your vet before adding melatonin or any calming supplement on top of trazodone.
Missed doses, daily use and stopping
Missed a dose? Give it when you remember, unless the next one is nearly due, in which case skip it. Never give two doses at once. That's how a calm dog turns into a stumbling one.
Can my dog take trazodone every day?
Yes, if your vet prescribes it that way. VCA says no specific monitoring is required, though your vet may want check-ins, especially for older dogs and dogs with liver or kidney issues. For older dogs with restless nights, our guide to melatonin for senior dogs covers what to ask the vet.
Stopping trazodone
If your dog takes it daily, ask your vet before stopping, and whether to taper the dose down.
What the research actually shows
The research is thinner than you'd expect. Most studies are small, and several had no placebo group.
| Study | Dogs | What it found | The catch |
|---|---|---|---|
| 2008 behaviour clinic case series | 56 dogs with anxiety disorders | Added to other behaviour drugs, it was generally well tolerated and helped calming | Looked back at records, with no controls and no figures on improvement |
| 2013 dosing study | 6 Beagles | The oral dose was absorbed well and well tolerated | Measured how the drug moves through the body, not behaviour |
| 2014 post-surgery trial | 36 dogs completed | About 90% of owners reported better calm and crate tolerance | No placebo group |
| 2016 hospital study | 117 dogs analysed | Fewer stress signs such as lip licking, panting and whining; after adjustment, panting and frantic behaviour stood out | Compared with matched untreated dogs, not a placebo |
| 2017 post-surgery trial | 29 dogs analysed | No better than placebo | Small |
| 2022 vet-visit trial | Each dog tried both trazodone and placebo | Owners and video reviewers scored stress lower | Investigators saw no difference, and heart rate was higher |
The two post-surgery studies tell the story. In 2014, about nine in ten owners liked what they saw, but everyone knew their dog was on the drug. When a team led by the same researcher ran a placebo-controlled trial in 2017, owners rated the placebo about as helpful. A 2023 Veterinary Evidence review called the overall support weak.
Still, it's generally well tolerated, and the 2016 hospital study is encouraging. Results vary, so your own dog's response is the evidence that matters most.
When trazodone doesn't seem to work
If the dose seemed to do nothing, timing is the usual suspect. Given too late, it's still being absorbed when the stress hits, and a dog who's already worked up is much harder to settle.
The dose may also be at the low end, where vets start on purpose. VCA notes that finding the right dose can take trial and error. Sometimes trazodone is simply the wrong tool.
Tell your vet when you gave it and what your dog did. Medication works best alongside behaviour work, and our complete calming guide covers the training and home changes that help. For the low-key nights in between, some owners keep a bottle of melatonin drops for dogs on the shelf, with their vet's OK.
Trazodone and gabapentin together
Vets sometimes pair trazodone with gabapentin for dogs before vet visits, but the evidence is thin. The only study we found is an unpublished conference poster comparing the combination with placebo, and no score differed significantly. Sedation was the most common side effect.
Try it only under your vet's guidance, never from leftover prescriptions. Our comparison of CBD versus gabapentin covers a related question.
Human trazodone vs dog trazodone
It's the same molecule, and in the US there's no veterinary-labelled version. That doesn't make your own pills fair game: your dose was set for you, and one human tablet can be far above a small dog's range.
Why Pure Majesty Pets Melatonin Drops for the milder days
A lot of everyday stress is smaller than what trazodone is for, like a dog who paces at bedtime. For those milder, predictable moments, some owners ask their vet about a non-prescription option. It's support for a calm routine, not a treatment, and never a replacement for a prescription.
Pure Majesty Pets Melatonin for Dogs is a xylitol-free liquid with 3 mg of melatonin per mL. Every active is listed by the exact amount per mL, with no proprietary blend, so your vet can see exactly what your dog would get. Each mL contains:
- Melatonin, 3 mg. VCA notes it's used in dogs for sleep and behaviour problems and usually takes effect in one to two hours.
- L-theanine, 50 mg. One small open-label study in storm-sensitive dogs reported improvements, but with no placebo group it's early evidence at best.
- Alpha-casozepine, 25 mg. A Veterinary Evidence review found no evidence that it helps when given shortly before a stressful event, and only limited, weak evidence for longer daily use.
- The rest of the formula is water-soluble chamomile extract (25 mg) and elemental magnesium (5 mg). It also contains vitamin B6 as P5P (0.5 mg). There's no dog research showing chamomile, magnesium or B6 calm dogs.
The xylitol-free part matters. VCA warns that human melatonin products may contain xylitol, which is toxic to dogs. It also advises caution with melatonin in young dogs, dogs that are pregnant, nursing or used for breeding, and dogs with severe liver disease.
Our drops are made in North America under GMP standards, and every batch comes with a certificate of analysis. Because it's a liquid, your vet can set small amounts for a small dog without anyone splitting tablets. A bottle is ₱2,100.00.
If your dog is already on trazodone, check with your vet before adding the drops, since no vet source we found says the two are fine together. For a side-by-side look, read our breakdown of melatonin vs trazodone for dogs. Our melatonin dosage chart lays out amounts by weight, and our roundup of over-the-counter options covers the rest.
If your vet agrees it fits your dog's milder days, you can find our calming and sleep drops here, with free worldwide shipping. It ships DDP, so duties and taxes are already paid and there's nothing extra to pay on delivery.
Trazodone for dogs: frequently asked questions
How long does trazodone last in dogs?
Sources differ. Owners in one post-surgery study reported effects lasting four hours or more. PetMD puts it at about 8 to 12 hours, and VCA says it should stop working within a day. Dogs with liver or kidney disease may feel it longer.
How fast does trazodone kick in for dogs?
Most dogs start to feel it within one to two hours. That's why vets usually ask you to give it at least 90 minutes before a trigger like a vet visit or fireworks. Giving it late is a common reason it seems not to work.
Is trazodone safe for dogs?
Most dogs tolerate it well when it's prescribed by a vet who knows their health and other medications. Dogs on MAO inhibitors or with angle-closure glaucoma shouldn't take it, and dogs with heart, liver or kidney disease need extra care. Never give it without a prescription.
What is the biggest side effect of trazodone in dogs?
Sleepiness is the most noticeable one, and it's partly the point. Vomiting, nausea and diarrhoea are also common. Watch for a paradoxical reaction, where a dog becomes agitated or aggressive instead of calmer. A fast heart rate, tremors or rigid muscles need a vet right away.
Can trazodone cause diarrhoea in dogs?
Yes. Diarrhoea is one of the more common side effects, along with vomiting and nausea, and it's usually mild. If your dog seems queasy on an empty stomach, VCA suggests giving the next dose with a meal or a small treat. If it's severe or comes with tremors or agitation, call your vet.
Is trazodone a painkiller for dogs?
No. Trazodone is used for fear, anxiety and sedation, not pain. Vets often prescribe it after surgery, but its job there is to help keep a dog calm during crate rest. Pain relief is a separate question for your vet.
Is trazodone approved for dogs?
In the US, no. The FDA has approved trazodone for people only, and vets there prescribe it for dogs extra-label, also called off-label, which is common in veterinary medicine. In the Philippines it's prescription-only, and your vet decides the dose based on your dog's weight and health.
Can I give my dog my own trazodone?
No. It's the same drug, but your dose was set for you, and a single human tablet can be far above the published range for a small dog. If your dog swallowed some of yours, contact your vet or an emergency vet clinic right away.
Sources
- Merck Veterinary Manual. Common Drugs Used to Treat Behavior Problems in Dogs (table). merckvetmanual.com
- Forsythe LR, Gollakner R. Trazodone. VCA Animal Hospitals, 2024. vcahospitals.com
- Williams K. Pre-Visit Pharmaceuticals for Dogs. VCA Animal Hospitals, 2024. vcahospitals.com
- Weir M, Barnette C. Serotonin Syndrome. VCA Animal Hospitals, 2025. vcahospitals.com
- Forsythe LR, Gollakner R. Selegiline. VCA Animal Hospitals, 2025. vcahospitals.com
- Hamilton A, Gollakner R. Melatonin. VCA Animal Hospitals, 2026. vcahospitals.com
- Lindell E, Horwitz D, Landsberg G. Behavior Counseling: Complementary Treatments. VCA Animal Hospitals, 2025. vcahospitals.com
- Howe S. Trazodone for Dogs. PetMD, updated September 2025.
- Sueda K, Cho J (updated by Gibson BR, Haug LI). Trazodone for Dogs & Cats. Clinician's Brief, 2016, modified 2025. cliniciansbrief.com
- Foss T. Trazodone in Veterinary Medicine. Today's Veterinary Nurse, 2017. todaysveterinarynurse.com
- ASPCApro. Understanding Trazodone Toxicosis. 2016, modified 2025. aspcapro.org
- Use of trazodone as an adjunctive agent in the treatment of canine anxiety disorders: 56 cases (1995-2007). J Am Vet Med Assoc. 2008;233(12):1902-1907. PubMed
- Gruen ME, Roe SC, Griffith E, Hamilton A, Sherman BL. Use of trazodone to facilitate postsurgical confinement in dogs. J Am Vet Med Assoc. 2014;245(3):296-301. PubMed Central
- Gilbert-Gregory SE, Stull JW, Rice MR, Herron ME. Effects of trazodone on behavioral signs of stress in hospitalized dogs. J Am Vet Med Assoc. 2016;249(11):1281-1291. Ohio State University (PDF)
- Sueda K. Trazodone to Reduce Stress in Hospitalized Dogs. Clinician's Brief, 2017. cliniciansbrief.com
- Jay AR, Krotscheck U, Parsley E, et al. Pharmacokinetics, bioavailability, and hemodynamic effects of trazodone after intravenous and oral administration of a single dose to dogs. Am J Vet Res. 2013;74(11):1450-1456. AGRIS (FAO)
- Clinician's Brief. Trazodone & Veterinary Examination Stress in Dogs (summary of Kim S-A, et al. J Am Vet Med Assoc. 2022;260(8):876-883). cliniciansbrief.com
- Dillon L. The efficacy of trazodone in reducing stress related behaviours in hospitalised dogs or dogs confined postsurgery. Veterinary Evidence. 2023;8(2). Includes data from Gruen ME, et al. J Vet Behav. 2017;22:41-45. veterinaryevidence.org
- Doenges R, Calder C. Use of trazodone and gabapentin to reduce fear, anxiety and stress during veterinary visits in client-owned dogs. Poster abstract, Mississippi State University.
- Branam E. Journal Club: Focus on Canine Noise-Induced Fear (includes Pike AL, Horwitz DF, Lobprise H. J Vet Behav. 2015;10(4):324-331). Today's Veterinary Practice, 2016. todaysveterinarypractice.com
- Buckley LA. Is Alpha-casozepine Efficacious at Reducing Anxiety in Dogs? Veterinary Evidence. 2017;2(3). doi:10.18849/ve.v2i3.67. veterinaryevidence.org
This article is for general information only and isn't a substitute for advice from your veterinarian. Trazodone is a prescription medication, and only your vet can decide whether it suits your dog and what dose to give. If you think your dog has had too much, or shows signs like tremors, a racing heart or seizures, contact your vet or an emergency clinic right away.