Antihistamines; safe use
While antihistamines are generally very safe in our pets, they have variable effects. Many human products are mixed with other medications, making them potentially dangerous to dogs and cats. Please follow these guidelines for antihistamine use in your animal.
1. VERY IMPORTANT
ONLY use a PURE antihistamine medication. This means NO "cold and flu" versions or similar. NO decongestants. NO anti-inflammatories. If you are unsure ASK A PHARMACIST
2. Generics are ok if they abide by rule 1. They should have the same active ingredients:
Benadryl is diphenhydramine
Reactine or Zyrtec are cetirizine
Claritin is loratadine
3. All can cause drowsiness, although this is more common with older generation ones (like diphenhydramine (Benadryl)). Simply reduce the dose if that is seen.
4. They do not work for all animals. For allergies, studies show about 25% of dogs or cats will respond to antihistamines. Sometimes an animal will respond to one antihistamine but not another, so trying more than one may be worthwhile.
5. If you are not seeing a response, or if the itch is severe, please contact your veterinarian. Antihistamine as NOT effective against infections, so not meant to be used for open wounds.
Dose guidelines:
Diphenhydramine (Benadryl) dose is 2- 4 mg/kg
Tablet size: 25mg
Give every 12 hours, increasing to every 8 hours (three times a day) if needed
3kg-5.5kg = 1/4 tablet
5.6- 10kg = 1/2 tablet
11-15kg = 1 tablet
16-25kg = 1 1/2 tablets
25kg- 30 kg = 2 tablets
30-35kg = 2 1/2 tablets
35-40kg = 3 tablets
Ceterizine (Reactine)
5kg -10kg = 5mg once daily
10-20kg= 5mg every 12 hours
20-40kg= 10mg once daily
Loratidine (Claritin)
<10 kg = 2.5 mg once daily
10–15 kg = 5 mg once daily
16–39 kg = 5 mg ever 12 hours OR 10mg once daily
40–69 kg = 10 mg every 12 hours
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1. VERY IMPORTANT
ONLY use a PURE antihistamine medication. This means NO "cold and flu" versions or similar. NO decongestants. NO anti-inflammatories. If you are unsure ASK A PHARMACIST
2. Generics are ok if they abide by rule 1. They should have the same active ingredients:
Benadryl is diphenhydramine
Reactine or Zyrtec are cetirizine
Claritin is loratadine
3. All can cause drowsiness, although this is more common with older generation ones (like diphenhydramine (Benadryl)). Simply reduce the dose if that is seen.
4. They do not work for all animals. For allergies, studies show about 25% of dogs or cats will respond to antihistamines. Sometimes an animal will respond to one antihistamine but not another, so trying more than one may be worthwhile.
5. If you are not seeing a response, or if the itch is severe, please contact your veterinarian. Antihistamine as NOT effective against infections, so not meant to be used for open wounds.
Dose guidelines:
Diphenhydramine (Benadryl) dose is 2- 4 mg/kg
Tablet size: 25mg
Give every 12 hours, increasing to every 8 hours (three times a day) if needed
3kg-5.5kg = 1/4 tablet
5.6- 10kg = 1/2 tablet
11-15kg = 1 tablet
16-25kg = 1 1/2 tablets
25kg- 30 kg = 2 tablets
30-35kg = 2 1/2 tablets
35-40kg = 3 tablets
Ceterizine (Reactine)
5kg -10kg = 5mg once daily
10-20kg= 5mg every 12 hours
20-40kg= 10mg once daily
Loratidine (Claritin)
<10 kg = 2.5 mg once daily
10–15 kg = 5 mg once daily
16–39 kg = 5 mg ever 12 hours OR 10mg once daily
40–69 kg = 10 mg every 12 hours
Back to Pet info page