Although Benadryl is designed for use in humans, veterinarians occasionally prescribe this medication to canine patients for seasonal allergies, motion sickness, and long-term management of mast cell tumors, among other uses. It can be helpful for pet owners to understand the correct dosage of Benadryl for dogs and necessary precautions to ensure your pet's safety when giving it.
Precautions Before Giving Benadryl to Dogs
Even with the correct dosing information, it's vital to take these precautions before giving your dog Benadryl.
- Contact your veterinarian. Always speak with your vet before giving your dog any medication -- over-the-counter or prescription. They know your dog's medical history and can give you the most accurate dose. Benadryl is not safe for dogs with certain conditions and can interact with other medications.
- Confirm the ingredients. Purchase Benadryl directly from your veterinary hospital or select a product containing only diphenhydramine, as common additives and flavorings can be toxic to dogs. Avoid liquid products containing alcohol or xylitol as well as decongestant formulas with ingredients like phenylephrine or acetaminophen.
- Asses your dog's condition. If your dog is suffering from an allergic reaction, particularly if they are having trouble breathing, experiencing vomiting, facial swelling, or pale gums, seek urgent veterinary care. Oral Benadryl does not take effect until about 20 to 30 minutes after ingestion, which could be too late in these cases.
- Know your dog's weight. While an adult human can take a standard dose of Benadryl, dogs come in a vast range of sizes. The right dose depends on their weight. If you do not have a recent weight for your dog or suspect that they may have gained or lost some weight since you weighed them last, hop them up on the scale.
Benadryl Dosage for Dogs
The recommended veterinary dosage of diphenhydramine (Benadryl) is 2 to 4 milligrams for every kilogram of body weight, which can be administered every 8 to 12 hours, or twice to three times daily. An easy way to calculate this at home is to give 1 milligram for every 1 pound of body weight, or use the guidelines below for low and high dose ranges.
This chart is not intended to replace veterinary guidance. Consult with your veterinarian to confirm that Benadryl is suitable for your pet prior to administration.
| Weight (pounds) | Amount of Benadryl (milligrams) |
| 10 lbs | 10 to 20 mg |
| 20 lbs | 18 to 36 mg |
| 30 lbs | 27 to 54 mg |
| 40 lbs | 36 to 72 mg |
| 50 lbs | 45 to 90 mg |
| 60 lbs | 54 to 109 mg |
| 70 lbs | 63 to 127 mg |
| 80 lbs | 72 to 145 mg |
| 90 lbs | 81 to 163 mg |
| 100 lbs + | 90 to 180 mg |
Benadryl typically comes in 25 mg and 50 mg tablets. If your dog is between doses or should receive a half or quarter tablet, use a pill cutter or blade to split the medication. For example, a 10-pound dog should receive 10 to 20 mg, which means ½ of a 25 mg tablet (equivalent to 12.5 mg) would be an appropriate dose for them.
Use Benadryl Safely
Each dog is an individual and may react differently to any given medication. If you do elect to give your pet Benadryl, do so under the direct guidance of your personal veterinarian. Monitor for any adverse side effects and avoid any formulas that contain ingredients other than diphenhydramine.
