Is your favorite doggo down with a terrible headache? Or perhaps an endlessly runny nose? From travelling sickness to weather-induced anxiety, there are many situations when your dog might feel pain or physical discomfort.
And if you are looking for an easy, over-the-counter solution for your sick canine, look no further.
Benadryl is a readily available, vet-recommended solution to some of the most common dog health problems. In fact, with the right guidance, Benadryl can be a life saver for dogs & humans alike.
Here’s what you need to know to before using Benadryl to treat your dog!
What is Benadryl?
Benadryl is a common anti-histamine drug which contains an active ingredient called diphenhydramine. If your near-by pharmacy does not sell Benadryl, there is no need to panic. They are most likely to have other alternative brands which will contain the same active ingredient – and will do the job just as well.

Being an anti-histamine, Benadryl is a common drug treating symptoms of allergies, motion sickness and hay fever in humans.
For more on the chemical mechanism of How Benadryl Works, see below.
Benadryl for Dogs
Generally speaking, pet-owners should always resist the temptation of running over the medicine cabinet to treat their pets if they show signs of sickness. In medical terms, doing this is important because humans and animals have vastly different ways of reacting to drugs.
Lucky for you, in the case of Benadryl – you are pretty much good to go. Although not FDA-approved for dogs, administering Benadryl to cats & dogs is a fairly common veterinary practice across the world.
For dogs in particular, Benadryl can be used to treat a range of allergies. Including seasonal or environmental as well as food allergies. It can also be used to relieve allergic reactions to a snake or insect bite.
Symptoms Treatable through the Use of Benadryl
When it comes to dogs, Benadryl is definitely the magical anti-dote you have been looking for!
Here’s are some of symptoms you can treat using Benadryl:
- Hives
- Itchy skin
- Facial swelling and inflammation
- Runny nose and eyes
- Coughing
- Sneezing
- Anaphylactic reaction
- Itchy skin
- Irritated skin
- Dog eye allergies
- Car sickness
- Insomnia
- Anxiety
- Insect or flea bites
- Bee stings
- Reaction to vaccines
- Asthma
Benadryl Dosage for Dogs
When it comes to Benadryl and dogs, the right dosage is key.
As a rule of thumb, the recommend dosage of Benadryl for dogs is 1mg for every 1lb of your dog’s body weight.
In most cases, the dosage is administered given 2 or 3 times per day.
However, according to the Merck Veterinary Manual, this standard dosage may fall anywhere between 0.9-1.8 milligrams (mg) of Benadryl per pound.
Size, breed, and age are important factors to consider before using Benadryl to treat a sick dog. Remember! These factors can change the standard guidelines for dosage. To be on the safe side, always seek your vet’s advice for help.
For smaller dogs and puppies, it is more common to use children Benadryl as it contains a lower dosage of diphenhydramine.
Here’s a helpful dosage chart you can use to determine how much Benadryl is needed:
- 30 lbs and smaller –10 mg per dose
- 30-50 lbs –25 mg per dose
- 50 lbs and over –50 mg per dose
How Long It Take for Benadryl to Kick In For Dogs:
Generally speaking, Benadryl has a fast absorption rate.
In most cases, it will take up to 30 to 60 minutes for Benadryl to kick in for your dog.
Did You Know?
The active ingredient in Benadryl (Diphenhydramine) is chemically similar to the active in Dramamine (a motion sickness drug). This mean Benadryl can be used to treat nausea and motion sickness when traveling. So if you’re planning a road trip with your furry friend, remember to keep a few tablets handy just in case.
How Does Benadryl Work?
Wondering how this magic drug works? Let us walk you through the chemical mechanism of Benadryl in five simple steps:
- An allergic reaction leads to the release of histamine in a dog’s body.
- Histamine can attach itself to H-1 receptors present in specific cells.
- Benadryl works by blocking H-1 receptors.
- Blocking h-1 receptors reverses the effects of histamine in capillaries.
- Reversing histamine action reduces allergic symptoms in your dog.
Side Effects of Using Benadryl in Dogs
Like most other medical drugs, Benadryl can have mild side effects. One of the most common side effects is causing drowsiness. So if the goal is to get your hyperactive doggo a little dose of calm – Benadryl can act as a good sedative!
Other common side effects include:
- Sedation of the central nervous system
- Dry mouth
- Urinary retention
- Hypersalivation
- Rapid heart rate
- Rapid breathing or difficulty breathing
Precautions when using Benadryl for Dogs:
- Avoid liquid Benadryl as dogs may find it hard to metabolize the drug in its liquid form. Instead, use tablets.
- If your dog doesn’t fancy the taste, you can always mix chunks of the medicine in dog food. Trust me, they would never know!
- Keep in mind that if your dog is suffering from pre-existing health conditions (say, glaucoma or pregnancy) – it is better to check with your vet before giving them a dose.
- Do not exceed recommended dosage without asking your vet. In case of extreme allergic reaction, your vet may decide to give a Benadryl injection.
In a nutshell…
Although Benadryl is a relatively harmless drug, there are a few caveats you need to look out for. From following the right dosage guidelines to knowing when to avoid the use of the medicine altogether – there are a number of factors to consider.
To make sure you are administering Benadryl in the right amount and manner, it is always best to check with a professional beforehand. Like they say, better safe than sorry!