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PetDosageChart

Chlor-Trimeton (Chlorpheniramine) Dosage for Dogs

First-generation antihistamine ⏱ Onset: 30-60 minutes ⏳ Duration: 8-12 hours

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. This information is sourced from veterinary drug references including Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

Dosage Calculator

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Chlor-Trimeton Dosage Chart for Dogs by Weight

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Weight Low Dose Standard Dose Max Dose Frequency
5 lbs (2.3 kg) 0.5mg 1mg 1mg Every 8-12 hours
10 lbs (4.5 kg) 1mg 1.5mg 2.5mg Every 8-12 hours
15 lbs (6.8 kg) 1.5mg 2.5mg 3.5mg (4mg tablet) Every 8-12 hours
20 lbs (9.1 kg) 2mg 3mg (4mg tablet) 4.5mg (4mg tablet) Every 8-12 hours
25 lbs (11.3 kg) 2.5mg 4mg (4mg tablet) 5.5mg Every 8-12 hours
30 lbs (13.6 kg) 2.5mg 5mg 7mg (2 × 4mg) Every 8-12 hours
40 lbs (18.1 kg) 3.5mg (4mg tablet) 6.5mg 9mg Every 8-12 hours
50 lbs (22.7 kg) 4.5mg (4mg tablet) 8mg (2 × 4mg) 11.5mg (3 × 4mg) Every 8-12 hours
60 lbs (27.2 kg) 5.5mg 9.5mg 13.5mg Every 8-12 hours
70 lbs (31.7 kg) 6.5mg 11mg (3 × 4mg) 16mg (4 × 4mg) Every 8-12 hours
80 lbs (36.3 kg) 7.5mg (2 × 4mg) 12.5mg (3 × 4mg) 18mg Every 8-12 hours
90 lbs (40.8 kg) 8mg (2 × 4mg) 14.5mg 20.5mg (5 × 4mg) Every 8-12 hours
100 lbs (45.4 kg) 9mg 16mg (4 × 4mg) 22.5mg Every 8-12 hours
120 lbs (54.4 kg) 11mg (3 × 4mg) 19mg (5 × 4mg) 27mg (7 × 4mg) Every 8-12 hours
150 lbs (68 kg) 13.5mg 24mg (6 × 4mg) 34mg Every 8-12 hours

What is Chlor-Trimeton (Chlorpheniramine) used for in dogs?

Allergies Itching Allergic reactions Hives Insect bite reactions

How to give Chlor-Trimeton to your dog

Give chlorpheniramine tablets by mouth with food to reduce stomach upset. The small 4 mg tablets can be given whole or hidden in a soft treat or pill pocket. If using syrup, measure the dose carefully with a syringe. Avoid any product containing decongestants (pseudoephedrine or phenylephrine). Maintain a consistent dosing schedule every 8-12 hours for best allergy control.

Available Forms

Tablet, Syrup

Give with Food?

Yes — give with food

Side effects of Chlor-Trimeton in dogs

Common side effects

Drowsiness
Dry mouth
Sedation
Decreased appetite

Serious side effects

  • Urinary retention
  • Severe sedation
  • Rapid heart rate
  • Seizures at high doses

When to call the vet

Call your vet immediately if your dog shows any of these signs:

  • Excessive sedation or inability to wake your dog
  • Difficulty urinating or no urine output
  • Rapid or irregular heartbeat
  • Tremors or seizure activity
  • Allergic reaction to the medication (facial swelling, hives, difficulty breathing)

Related Medications for Dogs

Antihistamine (first-generation)

Atarax

Hydroxyzine

For allergies

View dosage chart
Antihistamine (second-generation)

Zyrtec

Cetirizine

For allergies

View dosage chart
Antihistamine

Benadryl

Diphenhydramine

For allergies

View dosage chart
Antihistamine (second-generation)

Claritin

Loratadine

For allergies

View dosage chart

Sources & References

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Chlorpheniramine.

Frequently Asked Questions

How does chlorpheniramine compare to diphenhydramine (Benadryl) for dogs?
Chlorpheniramine is generally less sedating than diphenhydramine while still providing effective antihistamine action. It can be a good alternative for dogs that become too drowsy on Benadryl, though individual responses vary between dogs.
Can I use the human version of chlorpheniramine for my dog?
Plain chlorpheniramine tablets (4 mg) can be used, but you must avoid any formulations containing decongestants like pseudoephedrine or phenylephrine, as these are dangerous for dogs. Always check the ingredient list and consult your vet.
How long can my dog take chlorpheniramine?
Chlorpheniramine can be used long-term for chronic allergies under veterinary supervision. Unlike steroids, antihistamines have fewer long-term side effects. However, some dogs may develop tolerance over time, requiring a switch to a different antihistamine.
Will chlorpheniramine make my dog sleepy?
Drowsiness is the most common side effect, especially during the first few days of use. Most dogs develop some tolerance to the sedation over time. If excessive drowsiness persists, consult your vet about adjusting the dose.
Can chlorpheniramine be combined with other allergy treatments?
Yes, chlorpheniramine is often used alongside other treatments such as omega-3 fatty acids, medicated shampoos, or even other allergy medications under veterinary guidance. Combining therapies can improve allergy control.

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