Yes, trazodone can cause shaking in dogs. Tremors are a recognized side effect, though not one of the most common ones. In a clinical study of 59 dogs given trazodone, about 10% developed new trembling that wasn’t present before the medication. Shaking can also signal something more serious, like serotonin toxicity, so the context matters.
How Trazodone Can Trigger Shaking
Trazodone works by increasing serotonin activity in the brain. Serotonin helps regulate mood and anxiety, which is why the drug is prescribed as a sedative and anti-anxiety medication for dogs. But serotonin also plays a role in muscle control and body temperature regulation. When serotonin levels shift, some dogs respond with muscle tremors, fasciculations (small involuntary twitches), or full-body shaking.
This is similar to what’s seen in horses given trazodone, where muscle fasciculations and excessive sedation are documented side effects. The shaking is typically mild and resolves as the drug clears the body.
Common Side Effects vs. Serious Reactions
The more frequently reported side effects of trazodone in dogs are sedation, gastrointestinal issues (soft stool, vomiting, constipation), excessive thirst, panting, and occasionally increased agitation or anxiety. Some dogs experience the opposite of what you’d expect from a calming drug, becoming more restless or vocal.
Mild trembling falls into a gray area. In the clinical study mentioned above, trazodone actually reduced trembling in 8% of dogs (likely by easing their anxiety) while increasing it in 10%. So shaking can go either direction depending on the individual dog. A small amount of trembling that passes within a few hours is generally a mild side effect.
More concerning signs from trazodone toxicity include loss of coordination, disorientation, changes in heart rate (either unusually slow or fast), low or high blood pressure, urinary incontinence, slowed breathing, and seizures. The ASPCA lists tremors alongside seizures as signs that may appear with trazodone toxicosis, particularly at higher doses or in sensitive dogs.
Serotonin Syndrome: The Bigger Risk
The most dangerous cause of shaking in a dog on trazodone is serotonin syndrome, a condition where serotonin levels in the brain become dangerously high. This is rare with trazodone alone but becomes a real concern when trazodone is combined with other medications that also boost serotonin.
Drugs that raise the risk include SSRIs (like fluoxetine, commonly prescribed for dog anxiety), tramadol (a pain medication), and monoamine oxidase inhibitors. If your dog takes any of these alongside trazodone, the combination can push serotonin to toxic levels. Signs of serotonin syndrome include shivering or tremors, fever, rapid heart rate, diarrhea, confusion, and seizures. This is a veterinary emergency.
Other medications that require caution with trazodone include acepromazine, certain antibiotics (macrolides and fluoroquinolones), azole antifungals, NSAIDs, aspirin, and the anti-nausea drug ondansetron.
Dose and Timing
Trazodone is typically prescribed at a wide range, from about 1.7 to 19.5 mg per kilogram of body weight per day. When it’s used alongside another serotonin-affecting medication, vets usually start at a lower dose (2 to 5 mg/kg) and cap it at 14 mg/kg per day. Shaking is more likely at higher doses or when a dog first starts the medication and hasn’t adjusted yet.
Trazodone takes effect relatively quickly in dogs, usually within one to two hours. If shaking is going to happen as a simple side effect, you’ll typically notice it during that window. Sedation and related effects can last up to several hours. If trembling appears, stays mild, and fades as the drug wears off, it’s likely a straightforward side effect rather than something dangerous.
What to Watch For
Mild, brief trembling in an otherwise calm and responsive dog is the least worrisome scenario. Your dog may simply be sensitive to the serotonin shift, and the shaking should pass.
The picture changes if shaking comes with other symptoms. A dog that is trembling and also seems disoriented, uncoordinated, feverish, breathing abnormally, or has a racing heart needs immediate veterinary attention. Seizures alongside tremors are an emergency. If your dog is on multiple medications and develops shaking after starting or increasing trazodone, serotonin syndrome should be ruled out quickly.
Even without alarming symptoms, persistent shaking that doesn’t resolve within a few hours, or shaking that happens every time your dog takes trazodone, is worth discussing with your vet. A dose adjustment or switching to a different medication can often solve the problem.