Several human medications are used safely in dogs for anxiety, but almost all of them require a veterinarian to determine the correct dose for your specific dog. The one true over-the-counter option, diphenhydramine (Benadryl), is generally safe but not very effective for anxiety. The medications that actually work, like trazodone, gabapentin, fluoxetine, and alprazolam, are prescription drugs that vets routinely prescribe for dogs using human formulations. Here’s what each one does and when it’s appropriate.
Benadryl: Safe but Not Very Effective
Diphenhydramine (Benadryl) is the most commonly discussed over-the-counter option. The standard dose is about 1 mg per pound of body weight, given two to three times a day. It’s safe for most dogs, and you’ll find it recommended everywhere online for travel anxiety or noise phobias.
The problem is that it doesn’t really work for anxiety. Benadryl may make your dog drowsy and a bit sluggish, but it does nothing for the underlying fear or stress driving their behavior. A sedated dog that’s still terrified isn’t a calm dog. Some dogs even have a paradoxical reaction, becoming more hyperactive instead of sleepy. If your dog has mild travel jitters, it might take the edge off. For thunderstorm panic, separation anxiety, or vet visit fear, you need something that actually targets anxiety rather than just causing drowsiness.
Trazodone: The Go-To for Situational Anxiety
Trazodone is a human antidepressant that has become one of the most widely prescribed medications for short-term canine anxiety. Vets use it for stressful events like vet visits, car rides, boarding stays, thunderstorms, and post-surgery confinement. It works by increasing serotonin activity in the brain, which produces both a calming and mildly sedating effect.
For a single stressful event, trazodone works best when given about 90 minutes beforehand. Veterinary doses typically range from about 1.5 to 5 mg per pound, depending on the situation and the dog. Some dogs need it every 8 to 12 hours during prolonged stressful periods like hospitalization or recovery from surgery. The most common side effects are mild sedation and some unsteadiness, which is generally what you want in an acutely anxious dog. This is a prescription medication, so you’ll need your vet to determine the right dose.
Gabapentin: Calming Without Heavy Sedation
Gabapentin was originally developed for nerve pain and seizures in humans, but veterinary specialists now use it widely for situational anxiety in dogs. It dampens the nervous system’s overreaction to stressful stimuli, producing a calmer state without the heavy sedation of some other options.
For anxiety around vet visits, it’s often given the night before and again the morning of the appointment, about two to three hours before arrival. Some protocols start it two to three days before a known stressful event. Gabapentin pairs well with trazodone for dogs that need more help than either drug provides alone. Despite its widespread use among veterinary behaviorists, there are no published clinical studies specifically on gabapentin for situational anxiety in dogs. Its use is based on clinical experience and its known effects on the nervous system. Your vet can tailor the dose to your dog’s weight and anxiety level.
Fluoxetine and Clomipramine: For Ongoing Anxiety
If your dog has chronic anxiety, like separation anxiety that happens every time you leave the house, the medications above are band-aids. Two human antidepressants, fluoxetine (Prozac) and clomipramine (Clomicalm), are the only drugs FDA-approved in the United States specifically for treating canine separation anxiety. Both work by changing serotonin levels in the brain over time.
These aren’t quick fixes. They take several weeks of daily dosing before you’ll see behavioral changes, and they work best when combined with behavior modification training. In one study, 71% of dogs showed large or moderate improvement in separation-related problems when fluoxetine was combined with behavioral guidance. Clomipramine has been shown to reduce pacing, scratching, and whining in dogs left alone, while increasing calm, passive behavior. Both medications require a prescription, and your vet will likely recommend a gradual withdrawal once your dog’s behavior improves, since the goal is to use them as a bridge while training takes hold.
Alprazolam: For Panic and Phobias
Alprazolam (Xanax) is a benzodiazepine that works fast, making it useful for acute panic situations like thunderstorms, fireworks, or extreme vet visit fear. It can be given 30 to 60 minutes before an anticipated stressful event, or in the moment when a dog becomes severely distressed. For storm phobias, it’s typically given about an hour before the expected storm and repeated every four hours as needed.
Some vets also prescribe it over two to three days leading up to a known event to reduce anticipatory anxiety. Alprazolam is a controlled substance, so getting a prescription requires a veterinary visit and an established relationship with your vet. It’s effective for true panic reactions but isn’t appropriate for daily, long-term use.
Buspirone: For Generalized, Low-Grade Anxiety
Buspirone (BuSpar) is a human anti-anxiety medication that works well for dogs with generalized, ongoing nervousness rather than acute fear. Think of the dog that seems perpetually on edge around strangers or other animals, not the dog that panics during fireworks. It’s given two to three times daily and takes several weeks of consistent dosing to reach its full effect. A single dose won’t do anything noticeable. It’s not useful for panic-type reactions like thunderstorm phobias in either dogs or humans.
Melatonin: A Supplement Worth Considering
Melatonin is available over the counter and some owners find it helpful for mild anxiety, particularly around noise phobias like fireworks. For phobia-related use, a fast-acting oral form is typically given a couple of hours before the anticipated stressful event. It’s generally considered safe, but there’s one critical warning: some human melatonin products, especially gummies and chewables, contain xylitol (sometimes labeled as “birch sugar” or “sugar alcohol”), which is extremely toxic to dogs. Always check the ingredient list before giving your dog any human supplement.
Because melatonin supplements aren’t FDA-regulated, purity and potency can vary between brands. Your vet can recommend a trusted product and appropriate dose based on your dog’s size.
Hidden Dangers in Human Formulations
Even when a medication itself is safe for dogs, the human version may contain ingredients that aren’t. Xylitol is the biggest concern. It shows up in liquid medications, cough syrups, chewable tablets, mouthwash, and flavored supplements. In dogs, xylitol causes a rapid, dangerous drop in blood sugar and can lead to liver failure.
Liquid formulations of human medications are particularly risky because they often contain sweeteners or flavorings not listed prominently on the label. If your vet prescribes a human medication for your dog, ask specifically whether the tablet or liquid form is appropriate, and double-check for xylitol and other artificial sweeteners before administering anything.
Signs of Medication Toxicity
If your dog accidentally ingests too much of any anxiety medication, or has a bad reaction to a proper dose, the warning signs typically involve the gut, the heart, or the brain. Early signs include heavy drooling and vomiting. As toxicity progresses, you may see an abnormal heart rate, tremors, seizures, agitation, or unusual drowsiness. Fever, disorientation, and vocalization are especially common with serotonin syndrome, which can happen when serotonin-boosting medications are given at too high a dose or combined improperly. If you notice any of these signs, contact an emergency veterinary clinic or the ASPCA Animal Poison Control Center immediately.