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Home > Dogs > Can I Give My Dog Benadryl? Uses & Potential Side Effects

Can I Give My Dog Benadryl? Uses & Potential Side Effects

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Several over-the-counter medications formulated for humans can also be used for dogs. Benadryl is regularly used to treat several dog illnesses, like allergies and allergic reactions. Because it is safe for dogs in the correct dosage, it can be beneficial if used carefully. However, it should only be given to your dog when prescribed by a veterinarian.


When to Use Benadryl

Benadryl has many uses but most commonly is used to treat allergies under veterinary supervision.1 Other additional benefits are referred to as “off-label” uses. Your vet can prescribe Benadryl depending on the situation and will provide the dosing instructions for your particular pet.

Potential Side Effects

Like humans, dogs can experience side effects from medications. This is true for prescriptions they receive from the vet and over-the-counter meds like Benadryl. The most common signs are similar to those we experience from Benadryl, including:

  • Drowsiness
  • Dry mouth
  • Increased heart rate
  • Drooling

The good news is that these reactions often appear in the first hour after taking the medication and resolve fairly quickly. Because Benadryl must be dosed differently for dogs, it can easily be given incorrectly, causing an overdose and leading to several more severe reactions. If you notice any of the signs below, you should contact your vet immediately for guidance:

  • Dilated pupils
  • Rapid heartbeat
  • Constipation
  • Agitation
  • Seizures

Things to Consider

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Other Forms of Benadryl

An overdose can also happen using delayed-release Benadryl instead of regular tablets. A dog’s stomach digests food and medications differently, so a delayed-release pill may dissolve faster than the manufacturer intends. The tablet or capsule may also be changed if the dog chews it when administering it.

You should also avoid liquid forms of Benadryl because they often contain other ingredients that may be harmful or toxic, such as sodium or alcohol.

Allergy-Relief Alternatives

If your dog suffers from chronic allergies, you can ask your vet about Zyrtec or Claritin. These are over-the-counter allergy medications approved for humans that may have potential off-label usage for other species, as well.. They generally aren’t known to cause sleepiness, which is one of Benadryl’s most common side effects. The fast-acting formula of Benadryl should still be considered for allergic reactions, while Zyrtec and Claritin may be better options for long-term relief.

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Health Conditions

Benadryl is safe for most dogs as long as the medication doesn’t contain any other ingredients that could be harmful. However, it should be avoided if your pup is allergic to it or if they have other health conditions that the diphenhydramine would negatively affect. If your dog has any of the following health conditions or others, you should consult your veterinarian before giving them Benadryl:

  • Asthma
  • Heart disease
  • Hypothyroidism
  • Glaucoma
  • High blood pressure
  • Seizures
  • Pregnancy

Contact Your Vet

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Some allergic reactions cannot be resolved with Benadryl. For example, red and watery eyes could mean seasonal allergies or be a sign of glaucoma, in which case Benadryl would worsen matters. Unless your pup has a diagnosis that would confirm Benadryl is helpful or you’ve already spoken with their veterinarian about treating them with OTC medication, you should contact them before doing so.

divider-dog paw


Benadryl may be helpful for pets in certain situations. However, to use it safely you’ll need to begin by contacting your veterinarian first. Be sure to follow your vet’s recommendations and follow up with them if you have concerns about giving your dog Benadryl.

Featured Image Credit: A photographyy, Shutterstock

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