VETERINARY USE: Diphenhydramine (Benadryl) is generally safe for dogs. NEVER give to cats without vet approval.
OTC Antihistamine Calculator

Benadryl for Dogs

Calculate safe Diphenhydramine dosages for canine allergies, itching, bee stings, and mild motion sickness. Standard dosing: 1-2 mg per pound of body weight.

Standard Dose
1-2mg/lb
2-3 times daily as needed

Dosage Calculator

lbs = kg

Standard adult tablets are 25mg. Some are 50mg.

Children's Benadryl is typically 12.5mg/5mL

Important: Use ONLY plain Diphenhydramine. Avoid products with Tylenol, decongestants, or "Multi-Symptom" formulas - these are toxic to dogs.

CATS: Diphenhydramine dosing for cats is different and potentially dangerous. Always consult a vet before giving to cats.

Calculated Dose

Benadryl Dosage

For
Recommended Dose
mg
Tablet Amount
of mg tablet
Liquid Amount
using mg/5mL

Safe Range (1-2 mg/lb)

Minimum
Maximum
Max daily dose (3x):
🔁
Frequency
2-3x daily
⏱️
Duration
4-6 hours
🍽️
With Food
Optional

Benadryl Quick Reference Chart

Common dog weights with 1 mg/lb (conservative) and 2 mg/lb (max) doses

Dog Weight Conservative (1 mg/lb) Maximum (2 mg/lb) 25mg Tablets
10 lbs (4.5 kg) 10 mg 20 mg ½ tablet
20 lbs (9 kg) 20 mg 40 mg 1 tablet
30 lbs (13.6 kg) 30 mg 60 mg 1-1½ tablets
50 lbs (22.7 kg) 50 mg 100 mg 2 tablets
75 lbs (34 kg) 75 mg 150 mg 3 tablets
100 lbs (45 kg) 100 mg 200 mg 4 tablets

When to Use Benadryl for Dogs

🌸

Allergic Reactions

Skin allergies, hives, itching, environmental allergies, and bee stings

🚗

Motion Sickness

Car rides, nausea during travel. Give 30 min before departure.

😴

Mild Sedation

Light anxiety relief before grooming or vet visits (not for heavy sedation)

⚠️ Side Effects & Warnings

Common Side Effects

  • • Drowsiness and sedation
  • • Dry mouth
  • • Urinary retention
  • • Decreased appetite

When NOT to Use

  • • Glaucoma
  • • High blood pressure
  • • Cardiovascular disease
  • • Pregnant/nursing dogs

🚫 TOXIC Products to Avoid

Never give these Benadryl variants to dogs - they contain ingredients that are toxic to pets:

  • ❌ Benadryl-D (contains decongestant)
  • ❌ Benadryl Allergy Plus Congestion
  • ❌ Benadryl Multi-Symptom
  • ❌ Products with Acetaminophen
  • ❌ Products with Phenylephrine
  • ❌ Products with Xylitol (sweetener)

✅ SAFE: Use only plain Diphenhydramine (Benadryl Ultratabs or generic)

Frequently Asked Questions

Yes, plain Diphenhydramine intended for human use is safe for dogs at the proper dose (1-2 mg per pound). The key is ensuring the product contains ONLY Diphenhydramine as the active ingredient - no added pain relievers, decongestants, or artificial sweeteners.
Benadryl typically begins working within 30 minutes to 1 hour after administration. For motion sickness, give it 30 minutes before car travel. Effects usually last 4-6 hours.
While generally safe, some breeds may be more sensitive. Dogs with glaucoma, cardiovascular disease, hyperthyroidism, or urinary problems should avoid Benadryl. Always consult your vet before giving any medication, especially to puppies, seniors, or dogs with health conditions.
Yes, children's liquid Benadryl (12.5mg per 5mL) can be used for dogs. However, check that it does NOT contain xylitol or other artificial sweeteners, which are toxic to dogs. Use an oral syringe for accurate dosing.
Clinical Review
DVM
Reviewed by Dr. Igor I. Bussel, MD
Doctor of Veterinary Medicine
Last Updated: December 28, 2024
Sources & Guidelines
  • • ASPCA Animal Poison Control
  • • Plumb's Veterinary Drug Handbook
  • • Merck Veterinary Manual
Veterinary Pediatrics Peptides