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Benadryl Dosage For Dogs Based On Weight and Severity



Reviewed By: Dr. Joel Robertson

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Benadryl is a commonly used medication for humans, but did you know it can be just as helpful when treating your dog?

Benadryl dosage for dogs is determined by weight and severity of the ailment. In this blog post, we will explain how to correctly dose your pup with Benadryl so that they get the relief they need without any harm coming to them.

We’ll also discuss the potential side-effects and adverse reactions that can occur with Benadryl, so you can make an educated decision about when and how to administer it.

So let’s dive in and learn more about Benadryl dosage for dogs based on weight and severity!

Key Takeaway

  • Benadryl for dogs is an antihistamine medication, not FDA-approved but commonly used, that helps to alleviate the symptoms of allergies, including mild itching, and can also act as a mild sedative.
  • The general rule of thumb for Benadryl dosage for dogs is 1 milligram (mg) per pound of body weight, given 2-3 times a day, but always consult with a veterinarian before administering any medication.
  • Potential side effects of Benadryl include drowsiness, dizziness, dry mouth, constipation, nausea, vomiting, loss of appetite, and in some cases, impaired coordination, low blood pressure, blurry vision, and even sedation.

What is Benadryl For Dogs?

Benadryl Dosage For Dogs Based On Weight and Severity

Benadryl for dogs is an over-the-counter antihistamine medication often used to alleviate symptoms related to allergies, such as itching, hives, and swelling.

Benadryl, also known by its generic name diphenhydramine, can be a useful tool in managing various conditions in dogs.

It’s primarily known for its efficacy in treating mild to moderate symptoms of allergies, including environmental allergies like pollen, mold, and house mites.

Seasonal and food allergies can also be managed with this medication.

Besides its use in tackling allergies, Benadryl can also be beneficial in dealing with motion sickness during travels with your dog.

Benadryl Dosage Calculator For Dogs

Enter your dog’s weight (in pounds) and the concentration of Benadryl (in mg/ml) to calculate the recommended dosage:

Benadryl Dosage For Dogs Based On Weight

Dog’s Weight (lbs/kg)Benadryl Dosage (mg)
5 lbs / 2.27 kg5
10 lbs / 4.54 kg10
15 lbs / 6.80 kg15
20 lbs / 9.07 kg20
25 lbs / 11.34 kg25
30 lbs / 13.61 kg30
35 lbs / 15.88 kg35
40 lbs / 18.14 kg40
45 lbs / 20.41 kg45
50 lbs / 22.68 kg50
55 lbs / 24.95 kg55
60 lbs / 27.21 kg60
65 lbs / 29.48 kg65
70 lbs / 31.75 kg70
75 lbs / 34.02 kg75
80 lbs / 36.29 kg80
85 lbs / 38.56 kg85
90 lbs / 40.82 kg90
95 lbs / 43.09 kg95
100 lbs / 45.36 kg100

Benadryl Dosage For Dogs Based On Severity of Symptoms

Condition/SymptomsUse of BenadrylFrequencyDosage
Mild Allergic ReactionsBenadryl may be used to help alleviate minor symptoms like itching or a runny nose.Once a day1 mg per pound of weight
Moderate Allergic ReactionsFor more persistent symptoms, such as continuous itching or mild skin inflammation, Benadryl may be administered more regularly, but still within the safe dosage limits.Twice a day1 mg per pound of weight
Severe Allergic ReactionsIn cases of severe allergic reactions, immediate veterinary care is required. While Benadryl might be used in some cases, it’s typically part of a larger treatment plan.Twice a day1 mg per pound of weight
Motion SicknessBenadryl is often used to treat motion sickness in dogs, but always consult with a vet for the right dosage.Once a day1 mg per pound of weight
AnxietySome vets recommend Benadryl for dogs who experience anxiety, particularly during thunderstorms or fireworks.Once a day1 mg per pound of weight

Benadryl Dosage For Dogs Based On Age

Age of DogGeneral Guideline
Puppies (Under 1 year)Generally, it’s not recommended to give puppies any kind of medication unless instructed by a vet. Their bodies are still developing, and they may not be able to handle the same dosages as adult dogs.
Adult Dogs (1-7 years)The usual dosage of Benadryl for dogs is 1 mg per pound of body weight, given 2-3 times a day. But it’s always best to consult with a vet first.
Senior Dogs (8 years and older)Senior dogs often have different health considerations than younger dogs, so it’s important to talk to a vet before giving them any new medication, including Benadryl.

Benadryl Dosage For Dogs Based On Frequency

FrequencyGeneral Guideline
Single DoseA single dose might be given for mild symptoms such as a minor allergic reaction.
Twice DailyIf symptoms persist, the vet may recommend giving Benadryl twice a day – once in the morning and once in the evening.
Three Times DailyFor more severe or persistent symptoms, it may be necessary to give Benadryl three times a day. However, this should only be done under the guidance of a vet.

Benadryl Dosage For Dogs With Mast Cell Tumors

ConditionGeneral Guideline
Mast Cell Tumors (Without Symptoms)If the dog isn’t showing any symptoms, the vet might not recommend Benadryl.
Mast Cell Tumors (With Mild Symptoms)For mild symptoms like localized itching or redness, the usual dosage of Benadryl might be recommended (1 mg per pound of body weight, up to 2-3 times a day).
Mast Cell Tumors (With Severe Symptoms)For severe allergic reactions or other significant symptoms, the vet might recommend a higher dosage of Benadryl or other medications as part of a more comprehensive treatment plan.

Benadryl Dosage For Dogs To Calm Down

ConditionGeneral Guideline
Mild AnxietyFor mild anxiety, the usual dosage of Benadryl might be recommended (1 mg per pound of body weight). This should not be given more than 2-3 times a day.
Severe AnxietyFor severe anxiety, a vet might recommend a higher dosage or a different medication altogether. Benadryl is not a long-term solution for severe anxiety issues.
Frequent UseIf your dog needs to be calmed frequently (like daily), it’s important to talk to a vet about other options. Regular use of Benadryl might not be the best solution and could lead to side effects.

What Kind of Benadryl Should I Give My Dog?

The type of Benadryl you should give your dog is the plain, oral form that contains only the active ingredient diphenhydramine.

Benadryl comes in several forms, but the most appropriate for dogs is the simple, oral tablet or liquid form that contains only diphenhydramine as its active ingredient.

It’s crucial to avoid versions of the medication that include other ingredients like pseudoephedrine, acetaminophen, or alcohol, which can be harmful or even fatal to dogs.

The tablets are available in 25mg and 50mg strengths, but the 25mg size is generally the most suitable for pets.

Liquid Benadryl is also an option for dogs who might have difficulty swallowing pills. However, the dosage can be tricky because it’s typically formulated for humans.

Potential Side Effects of Benadryl In Dogs

The potential side effects of Benadryl in dogs can range from mild symptoms like drowsiness and dry mouth to more severe reactions such as urinary retention, rapid breathing, and increased heart rate, with rare occurrences of aggression, severe lethargy, abnormal heart rate, and even symptoms of poisoning like depression, drooling, and loss of appetite.


Just like in humans, one of the most common side effects of Benadryl in dogs is drowsiness or sleepiness. This is due to the sedative properties of the drug, which can cause your pet to feel tired or sluggish.

Dry Mouth

Dry mouth, also known as xerostomia, is another common side effect. This occurs when the salivary glands do not make enough saliva to keep the mouth wet. This can make your dog thirsty and potentially lead to dehydration if not properly managed.

Urinary Retention

Urinary retention, the inability to completely empty the bladder, can also occur in some dogs taking Benadryl. This can lead to discomfort and potential urinary tract issues if left untreated.

Increased Heart Rate and Rapid Breathing

Some dogs may experience a faster heart rate and rapid breathing as a side effect of Benadryl. It’s important to monitor your dog for these symptoms, as they could indicate a more serious reaction to the medication.

Rare Side Effects

In rare cases, dogs may exhibit signs of aggression or severe lethargy as a result of Benadryl overdose. Abnormal heart rate and symptoms of poisoning, such as depression, drooling, lack of appetite, and extreme excitability, could also occur.

How To Spot a Benadryl Overdose In Dogs

To spot a Benadryl overdose in dogs, look for key symptoms such as agitation, constipation, depression or hyperactivity, excessive salivating, dilated pupils, rapid heartbeat, rapid breathing, and in severe cases, neuromotor excitement or muscle tremors.


Agitation is one of the signs that your dog may have overdosed on Benadryl. This could manifest as restlessness, anxiety, or unusual excitement.


Overdose of Benadryl can also cause constipation in dogs. If your dog is having difficulty defecating or hasn’t had a bowel movement for a prolonged period, it may be a sign of an overdose.

Depression or Hyperactivity

Changes in mood or behavior are other potential signs of a Benadryl overdose. This could range from showing signs of depression, such as lethargy and disinterest in usual activities, to hyperactivity and increased energy levels.

Excessive Salivating

Excessive salivation or drooling can be another symptom of an overdose. If your dog is drooling more than usual, it’s a good idea to check with your vet.

Dilated Pupils

Dilated pupils can be another sign of a Benadryl overdose in dogs. If you notice that your dog’s pupils are larger than usual, it could be a symptom of an overdose.

Rapid Heartbeat

A rapid or irregular heartbeat is a serious sign of a potential overdose. If your dog’s heart is beating faster than normal or if the rhythm is irregular, seek veterinary care immediately.

Rapid Breathing

Rapid breathing can also indicate a Benadryl overdose. If your dog is panting excessively or seems to be struggling to catch their breath, get them to the vet.

Severe Symptoms

In severe cases of overdose, dogs may experience neuromotor excitement, which could manifest as muscle tremors or seizures. If you observe any of these severe symptoms, seek immediate veterinary assistance.

Alternatives To Benadryl For Dogs

Alternatives to Benadryl for dogs include other over-the-counter antihistamines like cetirizine (Zyrtec), loratadine (Claritin), hydroxyzine, and natural remedies such as EASE.

Cetirizine (Zyrtec)

Cetirizine, commonly sold under the brand name Zyrtec, is an effective antihistamine that doesn’t typically cause drowsiness in dogs. It can be used to relieve allergy symptoms and does not have the sedative effects often associated with Benadryl.

Loratadine (Claritin)

Loratadine, known by the brand name Claritin, is another safe antihistamine for dogs. It provides relief from allergy symptoms and is less likely to cause sedation compared to Benadryl.


Hydroxyzine is another OTC antihistamine that can be used as an alternative to Benadryl for dogs. It is primarily used to treat allergic skin reactions in dogs and can be a good option if your pet is dealing with skin allergies.

Natural Remedies – EASE

Natural alternatives like EASE can also be considered. EASE is a mixture of natural ingredients including frankincense and turmeric, which are known for their anti-inflammatory and immune-supportive properties. This can be a great option if you’re looking for a natural approach to managing your dog’s allergies.


Q: Can I give my dog Benadryl?

A: Yes, you can give your dog Benadryl, but it is important to consult with your vet first.

Q: Is Benadryl safe for dogs?

A: Yes, Benadryl is generally considered to be safe for dogs when given in the appropriate dosage. However, it is always recommended to consult with your vet before administering any medication to your pet.

Q: Are there any side effects of Benadryl in dogs?

A: While Benadryl is generally safe for dogs, some possible side effects may include drowsiness, dry mouth, and urinary retention. If you notice any concerning side effects, it is important to contact your vet.

Q: Can I use liquid Benadryl for my dog?

A: Yes, you can use liquid Benadryl for your dog. It is important to ensure that the liquid Benadryl does not contain any other ingredients that are harmful to dogs.

Q: Can I give Benadryl to my dog for motion sickness?

A: Yes, Benadryl can be used to help alleviate motion sickness in dogs. However, it is best to consult with your vet for the appropriate dosage and to determine if Benadryl is the best option for your dog’s motion sickness.

Q: What should I do if my dog accidentally overdoses on Benadryl?

A: If you suspect that your dog has overdosed on Benadryl, it is crucial to seek immediate veterinary care. Symptoms of Benadryl overdose may include extreme drowsiness, rapid heart rate, seizures, and difficulty breathing.

Conclusion and final thoughts

In conclusion, Benadryl is a great choice for treating dogs with allergies or other issues.

It is important to understand the correct dosage of Benadryl based on the weight and severity of your dog’s condition.

You should always consult with your veterinarian before administering any medication.

With proper usage, Benadryl can be a life-saver for your pup and help relieve them from their symptoms so they can enjoy life to the fullest.

Please take the time and leave a comment below if this article helped you, or you have any additional questions.

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