How Much Benadryl to Give a Dog | Dosage, Side Effects and so on

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Benadryl is a veterinarian drug, also called diphenhydramine. It's really common but hard for owners to know how much Benadryl to give a dog. You want the best for your pet, so you must know how to use it safely and how much Benadryl to give a dog. Let's start with us (Petscarehq) to know the best effective info.

Get this:

Some dogs can never use Benadryl in their lives, due to chronic conditions. Most people want to give over-the-counter products to their dogs without a veterinarian indication. It’s a bad decision.

 And you know what? Take a few minutes to read this, and you won’t risk making a mistake.

When we should not use Benadryl for dogs?

Will your dog tolerate Benadryl as a medication? Some conditions make it impossible for your pet to digest the drug, causing great harm. The best way is to consult a veterinarian, but in short, these are the conditions that don’t cope with the use of Benadryl:

  • Angle-closure glaucoma;
  • High blood pressure;
  • Cardiovascular Disease or heart failure;
  • Allergic lung disease;
  • Prostatic hypertrophy;
  • Seizures;
  • Pregnant dogs.

The presence of any of these above is a dangerous combination with the drug. Instead, ask a veterinarian what the best possible alternative to Benadryl is.

When to Give Benadryl?

Your dog isn’t included in the list above, and it’s probably safe to medicate it with Benadryl. The main problems that this medication is able to fight are listed below:

  • Seasonal allergies;
  • Allergies to food;
  • Varied environmental allergies, such as pollen;
  • Allergy to snake or insect bites;
  • Anxiety;
  • Treat Heartworm symptoms.

  • In case of allergies, they usually carry the following symptoms you may notice:

  • Red or itchy eyes;
  • Sneezing;
  • Runny nose;
  • Modifications on the skin.

  • Whenever these symptoms appear, it’s always a good idea to consult a veterinarian first. They are often related to allergies but can be due to some other disease. Then, you will make safer use of Benadryl.

    Which Type of Benadryl Should I Give to My Dog?

    Currently, the two common ways of giving Benadryl to your dog are the liquid and tablet forms. Some pet owners decided that liquid Benadryl for dogs is more comfortable to give. However, this doesn’t apply to every animal, and you should evaluate your own pet.

    With our charts, it will be very simple to medicate it. You only need to figure out first, what kind of Benadryl for dogs you want to use.

    Below, you will find the dog Benadryl dosage chart for the liquid version:



    30 lbs or Smaller


    30-50 lbs.


    50 lbs or Over


    With this chart based on the dog’s weight, it’s easier to find the right proportion to your pet. This dosage can be given 2-3x per day, at least 8 hours apart.

    Now, the dog Benadryl dosage chart mg based:



    30 lbs or Smaller

    10mg per dose

    30-50 lbs.

    25mg per dose

    50 lbs or Over

    50mg per dose

    An alternative to using this chart is to calculate 1mg of Benadryl x 1lb of the body weight. It’s the maximum safe dosage and higher than the first conservative dosage.

     It’s also essential to highlight the individuality of your dog. Whenever you give any kind of medication to it, watch closely for any symptoms. In case any severe secondary effect is noticed, take your dog to the veterinarian.

    Adverse Effects of Benadryl

    As with any other medication, the use of Benadryl in any of its types can have adverse effects. Among the secondary symptoms resulting from its use, you should expect:

    1. Common:

    Urinary retention;

    Dry mouth;

    Higher heart rate;


    Increase in salivation;

    Rapid breathing.

    2. Uncommon:

    Increased / decreases appetite;



    When experiencing a dog overdose on Benadryl symptoms aren’t hard to identify. Take your dog to a veterinarian immediately, if you notice any of the symptoms below:

    • Too much agitation (contrary to the sedation effect);
    • Seizures;
    • Rapid heart rate;
    • Constipation;
    • Dilated pupils.

    In such a case, the central nervous system of your dog is suffering from hyperstimulation. You shouldn’t wait for the outcome. However, sticking to the dog Benadryl dosage chart is a safer way to avoid such circumstances.

    Other Important Questions

    1. How long does it take for Benadryl to work for a dog?

    Benadryl is usually absorbed really quick and should start working after 30 minutes. It also depends on what you gave to your dog, to make it accept the medication.

    2. Will Benadryl make my dog sleepy?

    As it happens to us humans, antihistamine medications cause drowsiness and sedation. You should expect your dog to feel sleepy, and that’s normal. Many dog owners give Benadryl to their dogs to avoid car sickness, making them sleepy.

    3. Can I give my dog Benadryl for itching?

     Itching is usually related to allergies, which is the case for the use of Benadryl. However, if parasites or other diseases cause the itching, the symptoms may not cease.

    You are afraid that your dog suffers from allergies and other problems such as anxiety. Even so, giving any medication to your dog shouldn’t be a thoughtless decision. Medications that aren’t too hard on your pet, like Benadryl, also have side effects.

    Some dogs, due to chronic conditions, shouldn’t use the drug for any problem. In such cases, the treatment for the allergies or other problems should follow your veterinarian’s guidelines.

    Except for the cases mentioned above, Benadryl is very useful to calm down your dog or to treat an allergy. It’s essential, however, to always watch for side effects. Precaution comes first with our pets.

     Here are the main points to decide if you should and how much Benadryl to give a dog:


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      Really effective against allergies;
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      Quick effect (30 minutes);
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      Little to none adverse effects;
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      Diverse applicability (e.g., sedation).


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      Not suitable for every dog.

    With all this information, you are ready to decide about the suitability of this medication to your dog.

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