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If your dog suffers from anxiety, you might find online articles about different types of medications you can try. Trazodone and Benadryl are two medications used to treat anxiety in dogs. However, they're not the same. Trazodone is a prescription medication that produces a sedative effect, while Benadryl is an antihistamine that can make dogs drowsy.

Figuring out which medication is right for your anxious dog is crucial. Some pet parents may use Benadryl to help their dogs sleep during stressful situations like thunderstorms, fireworks, and vet visits. However, there are currently no clinical studies demonstrating its efficacy in treating anxiety in dogs. On the other hand, trazodone is a proven effective treatment for mild to severe anxiety in dogs, and it's a fast-acting short-lived medication that can help with various types of dog anxiety.

When comparing Benadryl vs. trazodone for dog anxiety, you should talk to your vet or a veterinary behaviorist who can help you learn more about your dog's anxiety or behavioral issues and find the best solution. This article will discuss everything you need to know about trazodone vs. Benadryl for dogs to help calm your anxious pup.

What Is Trazodone?

Trazodone is an anti-anxiety medication for dogs and cats. As a serotonin antagonist reuptake inhibitor (SARI) medication,1 it's used to treat a variety of behavioral issues in dogs, including separation anxiety, noise phobias, and situational anxiety. Trazodone is a human medication prescribed off-label for dogs and can help keep them calm in stressful situations.

Typically, trazodone is used as a short-term medication for predictable situational anxiety. For example, if your dog suffers from separation anxiety or fears the vet, you'll give them the proper trazodone dosage a few hours before the stressful event.

Unlike Benadryl, there has been comprehensive research on the effectiveness of trazodone in keeping dogs calm and treating dog anxiety. A recent study found that in dogs with anxiety given trazodone daily, 72.5% of pet parents stated that the medication was very effective.3


The most common use of trazodone for dogs is for short-term stress relief. However, since trazodone can take up to two hours or more to start working, you must be able to predict the stressful event. Unfortunately, if there's a storm you didn't know about, and your dog is afraid of thunder, giving them trazodone at the beginning of the storm won't quell their anxiety because the medication takes a few hours to kick in.

In a recent study on the use of trazodone in dogs after surgery, pet parents reported a median onset of 41 to 45 minutes.2 However, every dog is different, and it can take your dog much longer to start feeling the effects.

Since trazodone has a half-life of 2 to 3 hours,2 the effects only last around 6 to 12 hours. But remember, every dog is different. Therefore, it's crucial to monitor your dog when they first take trazodone to help you determine the onset and duration for your particular pet. For example, one dog might experience onset within an hour and have a duration of 10 hours, while another dog might experience onset within two hours with a duration of only six hours.

Additionally, some dogs might require daily trazodone, depending on their type and level of anxiety. If your vet determines your dog should be on trazodone daily, it can take several weeks to observe the full effects, similar to other anti-anxiety medications.

The main purpose of trazodone is to treat dog anxiety with a sedative effect, reducing systems such as:

Remember, trazodone can take a few hours to kick in, and the effects are short-lived, so it primarily benefits dogs who suffer from predictable situational anxiety or those with triggers. A few examples of when trazodone might be right for your dog include the following:

  • Separation anxiety: If your dog engages in destructive behavior, excessive vocalization like howling, or any other signs of anxiety while you're away, they may suffer from separation anxiety. Trazodone can reduce your dog's anxiety to help them feel calmer while you're away, also reducing their symptoms to prevent undesirable behaviors.
  • Fear of the vet: If your dog is afraid of the vet, trazodone can help your dog stay calm while being examined to ensure they get the treatment they need when needed.
  • Noise phobias: Thunderstorms and fireworks are two of the most common noise phobias in dogs. Luckily, they're both predictable. For example, you know your city will probably do fireworks on the Fourth of July, so you can ensure your dog takes trazodone a few hours before they begin to help them stay calm.
  • Travel anxiety: If your dog gets anxious while riding in the car, trazodone can help them stay calm and prevent them from trying to escape, vocalizing, or jumping onto you. Of course, we also recommend having a dog seat belt to keep them safe and prevent them from being able to move around the car while you're driving.
  • Holidays: The holidays can be stressful for dogs, especially if you're traveling or having company. Even holidays as seemingly innocent as Halloween can cause anxiety in dogs because of unknown sights, sounds, and smells. Trazodone may reduce symptoms of dog anxiety during these times.

Side effects of trazodone

Side Effects

Trazodone is a prescription anxiety medication for dogs. Unfortunately, while it's clinically proven to reduce anxiety symptoms in pets, every medication has potential side effects.

The most common side effect of trazodone for dogs is sedation, which is often the desired effect. The sedation can help your dog remain calm in stressful situations. A study on the use of trazodone for treating anxiety disorders in dogs found that most dogs tolerated it well, with 80% of dogs having zero adverse side effects.2

80% of dogs experience zero side effects when taking trazodone

Other possible side effects include GI upset, such as diarrhea, vomiting, and loss of appetite.4 However, these symptoms should subside after the trazodone has left their system. If your dog experiences side effects, consult your vet immediately for guidance.


Trazodone comes in 50, 100, 150, and 300-milligram tablets.5 The recommended dosage is determined by your dog's weight and level of anxiety.

For example, depending on your dog's symptoms, they might recommend a higher dose for vet visits and a lower dose for separation anxiety. In most cases, your vet will start your dog on a low dose and ask that you report back on their anxiety and any side effects to ensure the treatment is safe and effective. From there, your vet might keep the same dosage or continue increasing it to find the best one for your dog.

What Is Benadryl?

Benadryl, also known by its generic name diphenhydramine, is an antihistamine sold over the counter. It's most commonly used in people and pets to treat allergic reactions associated with seasonal allergies, bug bites, bee stings, and skin allergies. If you've ever taken Benadryl, you know it can make you drowsy, which is why it's a common anxiety treatment in dogs.

While this medication can make your dog tired, it's not considered an effective anxiety treatment, especially for dogs that suffer from mild to severe anxiety. Unfortunately, the sedative effects of Benadryl are too mild to help with most types of anxiety.6


As an antihistamine, Benadryl works the same in dogs as in humans, treating a wide range of allergic reactions from seasonal, environmental, and skin allergies.7 The most common uses of Benadryl for dogs include:

  • Swelling and inflammation
  • Hives and rashes
  • Runny nose and watery eyes
  • Coughing
  • Sneezing
  • Anaphylactic reactions7

Benadryl causes drowsiness, which may help with circumstantial anxiety in dogs caused by stressful events. It may reduce the symptoms of anxiety in dogs with mild anxiety. However, it's not ideal for dogs struggling with phobias, separation anxiety, fear-based anxiety, or any other type of mild to severe anxiety.6 That said, if your dog experiences anxiety in the car or during thunderstorms, it may help them stay calm because they'll feel tired. However, it's not an effective treatment for most types of anxiety in dogs.

Instead, prescription medications like trazodone are typically much more effective and can help sedate the dog while actively addressing anxiety symptoms.

In a recent study evaluating diphenhydramine as a sedative for dogs, researchers gave dogs diphenhydramine, saline, and acepromazine, a known prescription sedative for dogs. They assessed the dogs' levels of sedation with observation and interaction. Dogs in the acepromazine group experienced much higher levels of sedation than dogs in the saline or diphenhydramine groups.

Additionally, dogs given Benadryl didn't experience significantly different sedation from the dogs in the saline group. The results were that diphenhydramine didn't cause significant sedation in dogs, so it's not a suitable sedative for anxiety management.8

So can Benadryl relieve dog anxiety? Many people theorize that making dogs drowsy can help them stay calm. However, it's not an effective treatment for anxiety disorders in dogs because it doesn't have a significant anti-anxiety effect like other medications. It's possible Benadryl can help your dog stay calm in some situations, but you should always discuss all your options with your vet to ensure that it's the best course of treatment for their anxiety.

Side effects of Benadryl

Side Effects

The side effects of Benadryl for dogs are similar to those for humans. The most significant side effect is drowsiness. After the Benadryl starts working, you may see a reduction in your dog's allergy symptoms, but they'll probably nap more than usual.7 That said, your dog will still be able to go for walks and enjoy their favorite activities. If your dog is highly sedated, consult your vet immediately because it might indicate an overdose.

Other common side effects of Benadryl in dogs include:

  • Dry mouth
  • Urinary retention
  • Increased heart rate
  • Rapid breathing
  • Hypersalivation7

Some dogs shouldn't take Benadryl. While this medication is something you can buy over the counter at any drugstore, you should always consult your vet before administering it to your dog.


The recommended Benadryl dosage for dogs depends on their health and weight, and should only be used under the guidance of your vetWhile this medication is considered safe for dogs if you follow the recommended dosage, you should stop giving it to them and contact your vet as soon as possible if you notice any side effects. In addition, you should avoid giving Benadryl to puppies that can be more sensitive to some medications.7

Benadryl usually takes around a half hour to begin working. If you're using it for allergies, you may notice your dog scratching less or sleeping more because they're drowsy. The effects can last anywhere between eight and 12 hours. However, every dog is different. When you first start administering it to your dog, you can monitor them to determine onset and duration. You should report your findings back to your vet to help them create an effective treatment plan for your dog to prevent allergy symptoms from causing discomfort.

Always consult your vet if you're trying to use Benadryl to alleviate anxiety. It's unlikely they'll use Benadryl to treat your dog's anxiety because there are much more effective medications for mild to severe dog anxiety. However, if your vet chooses to use Benadryl, you should report any changes in behavior or side effects to ensure the medication is safe and effective.

It's crucial to pay close attention to the dosage to prevent potential Benadryl overdose. While rare, an overdose can cause dilated pupils, agitation, rapid heartbeat, constipation, and seizures.9 If you believe your dog has ingested too much Benadryl, contact your vet as soon as possible or call the Pet Poison Helpline at 855-764-7661 for guidance.

Never give your dog Benadryl without first consulting your vet. As we've mentioned, some dogs shouldn't have Benadryl because of pre-existing health conditions and medications.

Comparing Trazodone Vs. Benadryl

Chart comparing the class, uses, medication type, and side effects of trazodone vs. Benadryl

When comparing Benadryl vs. trazodone, you have to remember they're two completely different medications with different uses. However, one thing they have in common is that they've been used to treat anxiety. Unfortunately, there's no scientific evidence that Benadryl causes enough of an anti-anxiety effect to relieve anxiety symptoms in dogs. Instead, it mostly makes them drowsy, and a tired dog is less likely to be anxious. However, trazodone has been clinically proven to be an effective treatment for dog anxiety.

So what makes them so different? Trazodone is a prescription medication designed to treat depression and anxiety in people. It's used off-label for pets to treat various behavioral and anxiety disorders, including separation anxiety and fearful behavior. Meanwhile, Benadryl is an over-the-counter antihistamine designed for use in humans to treat allergic reactions. However, since one of the main side effects is drowsiness, it stands to reason that it may help dogs stay calm in stressful situations. That said, Benadryl hasn't been proven effective at treating dog anxiety.

Which is best for your dog? Ultimately, it depends on their type and level of anxiety. If you're looking for an effective allergy medicine for your dog to prevent them from scratching, choose Benadryl. However, trazodone is best if you're looking for a medication to help treat their anxiety.

Treating Anxiety In Dogs

Some pet parents use Benadryl to calm their dogs during travel, vet visits, and other events. However, anecdotal evidence can't paint a clear picture of just how effective Benadryl truly is. While this medication can make your dog drowsy, it can't necessarily calm them down if they feel intense anxiety. Instead, they'll be drowsy and anxious.

Finding the best anxiety treatment for your dog is crucial. There are so many different types of dog anxiety that can affect their quality of life, so you must consult a vet to help you find the best solution for your pet. For example, many dogs benefit from behavioral training to help them feel more confident in new situations and environments. Meanwhile, some dogs are naturally more anxious due to a history of abuse or negligence and may have to be on anxiety medication for their entire lives.

Finding the best treatment can help your dog live a happy, healthy life without debilitating anxiety that prevents them from enjoying their favorite activities. Working with a vet or veterinary behaviorist can help reduce your dog's anxiety, improve their quality of life, and help them cope with stress more easily.


What works better – trazodone or benadryl?

Trazodone is a proven anxiety medication for dogs, while Benadryl is an antihistamine that can treat allergies and cause drowsiness. While some pet parents report that Benadryl has helped their dogs through stressful situations, there's not enough clinical evidence to prove that this allergy medicine is an effective anxiety treatment.

Instead, if you want to help your dog's anxiety, most vets recommend trazodone because it's effective and fast-acting. That said, several other anxiety treatments are available, so it's best to discuss your dog's situation with your vet to find the best solution.

Is trazodone the same as Benadryl?

No, trazodone is not the same as Benadryl. Trazodone is a prescription anxiety medication for dogs, while Benadryl is an over-the-counter antihistamine. There are no studies demonstrating the effectiveness of Benadryl for treating dog anxiety, but because it induces drowsiness, it may help dogs fall asleep faster and stay relaxed in stressful situations.

Always consult your vet before giving your dog any medication. There are some dogs that shouldn't take Benadryl or trazodone. In addition, when you talk to your vet, be sure to discuss any other medications, supplements, or vitamins your dog takes to ensure there won't be any potentially dangerous interactions.

How long will trazodone keep my dog calm?

Trazodone can take two or more hours to work in some dogs. However, its effects can last anywhere from six to 12 hours. Ultimately, you won't know how long Trazodone will keep your dog calm until your vet gives you a treatment plan. Then, they'll most likely have you monitor your dog to determine onset and duration and tweak the dosage accordingly.

Young Black woman smiling while holding her terrier on the living room floor

Final Notes

Trazodone and Benadryl have both been used to help calm dogs. However, no clinical studies currently prove that benadryl is effective in treating anxiety in dogs. On the other hand, trazodone has been proven effective, and many pet parents use it to help their dogs stay calm in a variety of situations.

Considering trazodone vs. Benadryl for dogs? Consult a Dutch vet today. We specialize in behavior issues and anxiety to help you find the best treatment plan for your dog based on their health, type of anxiety, and fear levels. If appropriate, we can give you a trazodone prescription online to reduce your dog's anxiety. Try Dutch today.



  1. Shin, Justin J, and Abdolreza Saadabadi. Trazodone . 10 July 2022,

  2. Gruen, Margaret E, et al. "Use of Trazodone to Facilitate Postsurgical Confinement in Dogs." Journal of the American Veterinary Medical Association, U.S. National Library of Medicine, 1 Aug. 2014,

  3. Gruen, Margaret E., and Barbara L. Sherman. "Use of Trazodone as an Adjunctive Agent in the Treatment of Canine Anxiety Disorders: 56 Cases (1995–2007)." AVMA, 

  4. Maharaj, Nandini. “When Should Your Vet Use Trazodone for Your Dog?” American Kennel Club, 21 Mar. 2023,

  5. “Table: Drug Dosages for Behavioral Therapy in Dogs and Cats.” Merck Veterinary Manual

  6. “Can Benadryl Help with Dog Anxiety?” PetMD

  7. Burke, Anna. “Benadryl for Dogs.” American Kennel Club, 21 Sept. 2021,

  8. Hofmeister, Erik H, and Christine M Egger. “Evaluation of Diphenhydramine as a Sedative for Dogs.” Journal of the American Veterinary Medical Association, U.S. National Library of Medicine,

  9. “Benadryl Overdose in Dogs.” PetMD

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