Around 60% of dog owners in the United States use Benadryl (diphenhydramine HCl) for the treatment of, Seasonal allergies, skin allergies, food allergies, environmental allergies, insect bites allergies, anxiety, and motion sickness.
Benadryl is not an FDA-approved medicine for dogs; however, veterinarians legally prescribe the medicine off-label across the country.
Remember that the use of this ethanolamine-derivative antihistamine medicine for canines is effective but can be toxic for your pet at the same time.
Therefore this is essential for you to be aware of the possible side effects, safe dosage, safety precautions, and safe serving ideas of the medicine for your pet.

Benadryl Dosage For Dogs
The safe Benadryl dosage for dogs is 2-4 mg/kg (0.9-1.8 mg/lb) two to three times a day. The ideal form of Benadryl for dogs is the children’s chewable pills that usually come in strength of 12.5 mg.
The dose of diphenhydramine HCl can be increased or decreased depending on the severity of the problem, size, weight, breed, and overall health of your pet.

If you are using Benadryl tablets for your pet, make sure to cut and divide the tablets according to your pup’s body weight.
Never overdose your canine on the medicine, and also avoid giving the capsule and liquid Benadryl that contain sodium chloride or xylitol.
Such forms of medicine may harm more than benefit.
Dosage Calculator:
Benadryl Dosage Chart For Dogs By Weight
Dog Weight in kg | Dog Weight in lbs | Benadryl Dosage 2-4 mg/kg (0.9-1.8 mg/lb) |
---|---|---|
3 kg | 7 lbs | 6-12 mg |
5 kg | 11 lbs | 10-20 mg |
10 kg | 22 lbs | 20-40 mg |
15 kg | 33 lbs | 30-60 mg |
20 kg | 44 lbs | 40-80 mg |
25 kg | 55 lbs | 50-100 mg |
30 kg | 66 lbs | 60-120 mg |
35 kg | 77 lbs | 70-140 mg |
40 kg | 88 lbs | 80-160 mg |
50 kg | 110 lbs | 100-200 mg |
kg Dog Weight | Benadryl 25mg for dogs Dosage (2-4 mg/kg) |
---|---|
3 kg | 1/4 Tablet |
5 kg | 1/2 Tablet |
10 kg | 1 Tablet |
15 kg | 1, 1/4 Tablets |
20 kg | 1, 1/2 Tablets |
25 kg | 2 Tablets |
30 kg | 2, 1/4 Tablets |
35 kg | 2, 1/2 Tablets |
40 kg | 3 Tablets |
50 kg | 4 Tablets |
Dog Weight | Children 12.5 mg Benadryl Chewable pills (2-4 mg/kg) |
---|---|
3 kg | 1/2 Tablet |
5 kg | 1 Tablet |
10 kg | 1, 1/2 Tablet |
15 kg | 2 Tablets |
20 kg | 3 Tablets |
For safety precautions and to avoid any toxic reaction, we suggest you go with the minimum dose and only increase the amount with the vet’s advice.
How does Benadryl work?
Benadryl is an antihistamine drug that contains diphenhydramine HCl that works by blocking histamine, which is a natural substance created by the body during an allergic reaction.
Use of Benadryl in Dogs
Benadryl is commonly used for the treatment of symptoms associated with allergies, motion sickness, travel, fireworks anxiety, and thunderstorm anxiety.
The common uses of Benadryl (diphenhydramine HCl) in dogs are:
- Rashes
- Itching
- Runny nose
- Watery eyes
- Cough
- Sneezing
- Hives
- Anaphylactic reaction
- Mild sedation.
- Heartworm treatment
- Swelling and inflammation
- Mast cell tumors
Benadryl Side Effects in Dogs
The side effects of Benadryl in canines can be minor or severe.
Minor side effects:
- Vomiting
- Diarrhea
- Drowsiness
- Dry mouth
- Decreased appetite
- Increased appetite
Severe side effects:
- Urinary retention
- Hypersalivation
- Increased heart rate
- Rapid breathing
Benadryl Overdose in Dogs
The symptoms of Benadryl overdose or any other related side effects usually appear within 30 minutes to 1 hour after administering the medicine.
Keep a close eye on your pet after giving the pills and contact your vet immediately if symptoms such as:
Benadryl overdose Symptoms are:
- Increase heart rate
- Dilated pupils
- Difficulty Breathing
- Extreme Restlessness
- Growling
- Agitation
- Seizures
- Loss control on urination
- Pale gums
- Dilated pupils
Can I give liquid Benadryl to my dog?

Liquid Benadryl, which only contains diphenhydramine, is safe for dogs and is the best choice for small puppies.
However, the liquid Benadryl usually contains toxic ingredients such as sodium, xylitol, alcohol and other toxic artificial flavors that can harm your dog; such children’s liquid Benadryl should be avoided for giving to your puppy.
Which dogs should not take Benadryl?

Benadryl is not safe for all dogs. Canines hypersensitive to the medicine or having health issues such as heart issues, kidney and liver issues, Glaucoma, Hypothyroidism, Hypertension, lung illnesses, and seizures should not take Benadryl.
Pregnant pets and pets aged less than 2 months should not take Benadryl without a veterinarian prescription.
How to give Benadryl to dogs?
- Never give medicine to your pooch without a vet’s prescription.
- Choose the safe form of Benadryl for your dog and select the product that only contains the active ingredient diphenhydramine and avoid the product that contains any other additional ingredients.
- The best way of giving the medicine is to hide the pill from in best canine diet or to mix the liquid form in the food.
- Never overdose your pet on Benadryl. It is toxic and can even be fatal.
- Keep a gap of at least 12 hours if following b.i.d and at least 8 hours if you are following t.i.d.
- Never give two doses at a time.
- Keep the medicine out of the reach of children and your pet.
- In case of any adverse reactions, contact your nearby veterinarian immediately.
When to give benadryl to dogs for motion sickness?
For treating motion sickness or travel anxiety in dogs you must give benadryl to the pet 30 to 60 minutes before the travel. The medicine can be used with or without food.
You May Also Like To Read:
- Rilexine Dosage For Dogs | Cephalexin Dosage Chart
- Minocycline Dosage For Dogs | Minocin® Dose Chart By Weight
FAQ:
Can I give my dog 25mg of Benadryl?
If you are using the 25mg Benadryl for your dog, make sure to calculate the correct dosage, either by dividing the tablet into pieces or adding extra pills according to the weight.
Do not give a 25mg Benadryl tablet to a puppy for which it is not the correct dosage by weight.
Can I give my dog Benadryl every day?
Yes, you can give your dog Benadryl every day for 3 to 7 days duration with your vet prescription. Never give the medicine when your pet heals, and the treatment duration is completed.
Long use of Benadryl can cause health complications in your pet.
Does Benadryl make dogs sleepy?
Yes, Benadryl has the effect of mild sedation on dogs, and your pet may appear sleepy after taking the medicine.
How long does it take Benadryl to calm a dog?
Benadryl can take about 30 minutes to one hour to start its effect. You can notice the calming effect of the medicine at least 30 min after the administration.
Should I give my dog Benadryl for anxiety?
Yes, veterinarians often prescribe Benadryl for treating anxiety in dogs, including fireworks anxiety, thunderstorm anxiety, travel anxiety, etc.