Giving Benadryl to Your Dog — The Complete Guide

Giving Benadryl to your dog: should you do it?

Is it helpful and harmless?

Or is it dangerous and a bad idea?

Used properly, in the right situations, Benadryl can be a lifesaver—preventing headaches and alleviating discomfort for your dog.

Before we get started, a disclaimer: it’s always a good idea to talk to your vet about giving medication to your dog. If you can’t make it in for an appointment, try just giving your vet a call to ask their opinion if you’re worried about giving your dog Benadryl.

What Is Benadryl & Where Can You Get It?

Benadryl is a common over-the-counter antihistamine that you can buy at any drug store, pharmacy, or grocery store.

Like other antihistamines, its primary use is to help reduce symptoms associated with allergies such as sneezing and runny nose.

Keep in mind that Benadryl is the brand name for the active ingredient called diphenhydramine. So even if your store doesn’t sell Benadryl, they almost certainly offer a different brand with the same active ingredient. Check the “Drug Facts” on the back of the label and look for diphenhydramine as the Active Ingredient.

Benadryl’s Uses for Dogs

Benadryl absorbs very quickly and usually begins to take effect after about 30 minutes. Benadryl can be helpful if your dog has any of these symptoms:

  • Itchy skin
  • Irritated skin
  • Nausea
  • Car sickness
  • Insomnia
  • Anxiety
  • Insect or flea bites
  • Bee stings
  • Reaction to vaccines
  • Hay fever, sneezing, or coughing
  • Stuffy or runny nose
  • Asthma
  • Allergies

Is Benadryl Safe for Pets?

Generally speaking, yes.

Benadryl is a relatively harmless drug that should be totally safe for your dog.

But there are a few caveats:

Benadryl might not be safe for puppies. If your dog is a little pup, ask your vet first. Just as you have to be careful giving medications to human babies, you have to be careful with what you give a puppy. They’re small and may not have fully developed

Avoid combination Cold/Sinus medications. Diphenhydramine is safe for dogs—but many of the other cold and sinus ingredients (including fever reducers, decongestants, and expectorants) may not be. Make sure diphenhydramine is the ONLY active ingredient listed on the label.

Steer clear of liquid Benadryl. In liquid form, Benadryl has high alcohol content that will be unsafe for your pet.

It’s counter-indicated with some conditions. If your dog has prostatic disease, glaucoma, cardiovascular disease, or hyperthyroidism, definitely check with your vet to make sure Benadryl is safe for your pet.

Watch for formulas containing sodium. Some Benadryl formulas (such as children’s versions) contain sodium, which could be problematic for dogs with certain health conditions who are taking medications. To be on the safe side, look for a form of Benadryl that does not contain sodium.

Do not exceed the recommended dosage. More details on this below.

Getting the Dosage Right (How Much Benadryl Does Your Dog Need?)

The amount of Benadryl your dog needs depends on its size.

The easy (and less precise) way to determine this is to put your dog into one of three categories:

  • 30 lbs and smaller – give 10 mg per dose
  • 30-50 lbs – give 25 mg per dose
  • 50 lbs and over – give 50 mg per dose

That should give you a fairly accurate dosage.

If you want to be more precise, the formula to do that is to give your dog 1 mg of Benadryl for every 1 lb of body weight.

So a 35-pound dog should get 35 mg of Benadryl per dose. The Benadryl dose for 16 lb dog would be 16mg.

Ask your vet for more help with dosing frequency, but the typical dose is 3 times a day, every 8 hours apart.

Potential Side Effects of Benadryl

Being a safe medication, Benadryl’s side effects are on the mild side.

The most commonly reported side effect is drowsiness. This is so common that many people give Benadryl to their dogs to help them calm down. (Diphenhydramine is even marketed and used as a sleep-aid by many people.)

The second most common side effect is mild disorientation. We recommend paying attention to your dog’s behavior after giving them Benadryl to make sure they don’t experience this before giving them a second dose.

Other, less common side effects include:

  • Dry mouth
  • Breathing problems
  • Diarrhea
  • Lack of appetite
  • Vomiting
  • Agitation
  • Rapid heartbeat
  • Urinary retention (not peeing)

If you think your dog is experiencing any of these side effects, give your vet a call.

Tips for Giving Benadryl to Your Dog

Test it first. Instead of giving your dog a full dose right off the bat, try giving them a small amount of Benadryl and waiting for a few hours. Watch your dog for any signs of side effects or reactions.

Always give it with food. One way to avoid some of Benadryl’s side effects (such as nausea and lack of appetite) is to give it to your dog with a meal or a dog treat.

Break up tablets and put it into a piece of meat. Most dogs are less than eager to swallow a whole pill. But if you break the pill up into chunks and place them inside a piece of meat, your dog will wolf it down without ever knowing there was a pill inside.

Mix liquid gel Benadryl with wet food. If you have a liquid gelcap, try breaking it open and mixing it with some wet food containing gravy. Your dog will never taste the Benadryl (and they’ll love the gravy).



  • Heather

    Can bullymax help with skin irritation? My pitbull (6months) stays inside but goes out to use the bathroom, so we have to bath him quiet regularly. He had also had itchy, red, irritated skin. I use special veterinary hot spot shampoo but it only helps some.

  • kathy barrow

    My brother left the benadryl down and ou dog are 14 benadryl is it going to hurt her

    • We would recommend contacting your veterinarian immediately.


    I have a 145 pound Saint Bernard mix who is having an allergic reaction right now. The vet told me this afternoon to give him prednesone 2x a day and 300mg (!) of bennedryl 3x a day (!)

    I have him 12 25s around 3pm and then another 12 around 10pm… I think the dose was too much! He actually seems to be in less discomfort now, but appears kind of high or drunk.. maybe I’m just projecting what I would expect.. is 900mg/day a safe dose ever??

    • With any medical emergency, we always recommend taking your vet’s advice. In certain situations (such as a snake bite), veterinarians normally recommend 2 mgs per pound of body weight. So the 300mg recommendation makes sense in some cases.

  • Leo

    What about a dog with a cold/runny nose will Benadryl help? At least stop the runny nose? or is there an over the counter medication for dogs with colds/runny nose. ( like at a pet store ) At this time, I cannot afford to take him to a Vet. Looking for a home remedy or an over the counter medication for dogs… Thanks so much for answering.

    • JoJo

      I read some where you can give them robitussin for cough, Pepto/Keopetate for diarrhea, and Dramamine for car sickness. That’s all the “human” meds I can recall.

      • Leo

        Hi JoJo,
        Thank you for replying, after I left that msg/question I continued to do my own research, and found Vibactra !!! All Natural Herbal Antibiotic I will be placing an order. It’s EXACTLY what I was looking for YAY!

  • Melissa granger

    Our dog is a little dog and has the collapsed trachea…so the vet said give him benadryl….he is only 12.5 lbs…can I give it to him everyday? Or is that too much? He wakes up in the middle of the night hacking and kinda sounds like a

    • CrowMeris

      Ask your vet to be certain, but generally yes – you can give it every day, but only as long as he really needs it. Start on half the recommended dose (twelve milligrams/dose for a twelve pound dog) and see if that works (that would be six milligrams/dose or one-quarter of a 25 milligram tablet).

    • Brtall

      That depends on what form you are givng. Liquid or pill. The pill of often 25mg, enough for a 25lb dog. Your dog being 12.5lb’s would need about half the pill, and you can give it to him twice a day. If you have teh liquid form, check how many mg of drug is in a 5ml dose.

      If giving the correct size dose, you should be able to give it to your dog 2 – 3 times a day.

      • Tausha Barker

        Brtall the article above said do not give them liquid Benadryl because it has sodium in it.

  • Debbie Sidell

    I bought a quickfinder nail clipper because my dog’s nails are ridiculously long and when I tried to clip her nails I didn’t even get near the nail and she bit me. I was wondering if I could give her enough Benadryl to knock her out so I could clip her nails? Any experience or any advice would be really helpful. Thanks!

    • I would not recommend using benadryl as a sedative. Walking your dog on a concrete will do the trick.

  • Amanda

    My dog had reacted to the vaccines about 2 days ago and had a high dosage of benadryl to counteract the swelling in her face. She’s been good now but had started to have diarrhea two days later. Is this normal?

  • Tiffeny

    My dog is having an allergic reaction right now. Shes having a reaction to her rabies vaccination. Within an hour she broke out in hives and has swollen eyes and mouth. Her first dose of benadryl was liquid about 30ml, it helped quickly and she slept for a couple hours. 5hrs later she became itchy and swollen again. I have her another dose, This time chewable tabs ( she fought me with the liquid and I couldn’t get it in her again, plus I read to avoid liquid) it does not seem to be helping as effectively this time, plus she is shaking her head alot. Should I continue with benadryl in another 4 hours? I plan to call vet in the am but I don’t know what to do for the rest of the night. I have a 4yr old female pitbull , she’s about 50 lbs.

    • If the Benadryl isn’t working, I would recommend contacting an emergency vet that’s open 24 hours.

  • Sarah` White

    My bichon has skin allergies. How long can Benedryl be used in this case. Is it dangerous to give it to her indefinitely….can it harm her if taken over a prolonged time?

  • Renee

    Hi guys, I have an Aussie bulldog (sorry not a pit bull) but he is terrified in storms, so much that no matter where he is, he escapes and runs away. Due to current circumstances I am unable to have him inside in a storm, especially when they hit during the day.. what is recommend to knock him out enough so that he doesn’t climb out of his enclosure?

  • Ari

    I have a Chihuahua mix and last time he was weighed he was 15 pounds but I believe he is not about 20 pounds. I have been giving him half a tablet of 25mg. At first every 24 hours and now at the moment every 12 hours. He has bad environment allergies.
    Do you think I can give him an entire tablet of Benadryl every 24 hours?
    Or should I just give him half the tablet every 8 hours? Though it’s not easy as I’m away from home 7am to 5:30pm. But I can start I can give it to him tonight and then have someone give it to him on Friday when I’m not home. And then I’ll be home Saturday and Sunday.
    I plan on starting him on fish oil. And I am currently spraying spraying him with a dog itch relief tea tree. And will buy him GNC itch relief shampoo.

  • Sondra

    Gave our 4yr old 17lb yorkie bath with medicated shampoo (we never use this ) she broke out in hives pea and dime size…we have given about 5ml of children’s liquid …they haven’t gotten worse but haven’t gotten better either …any suggestions? ??

  • Tricia Martin

    For those that are giving their pets Benadryl on a regular basis because of skin allergies or something of the sort, I would recommend trying to find thine source of the allergy, dryness, irritation, or whatever and treating that. Speaking from personal experience, I because allergic to antihistamine from taking it so much because of allergies. I still have allergies but now can’t take antihistamine so I have learned to find and eliminate causes as much as possible or find more natural ways to treat the symptoms. I’m not saying not to use this, but maybe sparingly is better. I’m not a vet though. Just someone with personal experience. I have been able to change the condition of my pets’ skin by changing what they eat and what I bath them with.

  • adam

    The recommended dosage makes no sense at all. If this theory was applied to humans, a two hundred pound man would take 200mg of Benadryl. It’s strange to see such advice given by professionals. Dogs 20 pounds and under should get a children benadryl at 12.5 mg. Dogs 20 – 40 pounds should get a 25 mg dosage and dogs 40 pounds and above should get 25-50 mg dosage dependent upon ailment. Most people are absent of the fact that 50 mg of Benadryl is actually used as a sleeping aid for humans. I can’t imagine any dog ever needing more than 50 mg of benadryl at one time.