Over-the-Counter Medications for Pets – Part 2 of 3

This is a continuation of Part 1 which can be found here. Please read that post first. I’m also supposed to tell you that paid links in this post help to support this blog. I also need to buy chocolate, so help a girl out!


When it comes to anti-histamines, you have to be very careful to pick the correct product. Many of these drugs are sold in a variety of different combination formulas. You’re going to want to stick with those that only list one active ingredient. Anything that states it’s for congestion, sinuses, multi-sympom relief, or cold and flu probably contains ingredients that are toxic to dog or fatal to cats. If the product has a -D in the name, you can’t give this to your pet (example = Claritin-D).

Benadryl (diphenhydramine)

Benadryl is an anti-histamine medication that is commonly used in dogs and occasionally in cats after having an allergic reaction, for seasonal allergies, for mild sedation, or as part of a treatment protocol for mast cell tumors.

Diphenhydramine acts on the histamine receptors in the body to counteract the physiologic response that results in the symptoms of an allergic reaction. Some dogs/cats may experience mild sedation because the drug also affects these receptors in the brain. Uncommonly, some pets will become hyperactive after this drug.

Liquid Children’s Benadryl

Benadryl is available in liqui-gels and tablets of 25 mg. Children’s Benadryl is also available and comes in both a liquid or a chewable and flavored tablet. The Children’s Benadryl tablets are large and grape-flavored which might make them more challenging to get into your pet.

Chewable Children’s Benadryl

Topical versions are also on the market, but pets tend to lick these off so they aren’t recommended as frequently in dogs or cats. Make sure to avoid any combination products for congestion and sinus pressure since these contain drugs that might be toxic to your pet.

Many generics and store-brand versions of diphenhydramine are on the market, usually labeled “Allergy Relief” or “Sleep-Aid.” Some of these come in 50 mg sizes, so read the labels carefully.

Outside of the United States, Benadryl may contain a different active ingredient than diphenhydramine.

Other Anti-histamines

Since allergies are a common problem in people, numerous other anti-histamines are on the market over-the-counter. Many dogs or cats require prescription-strength medication if they have allergies. Anti-histamines don’t always work well for them. But if your vet does recommend trying them, here are some of the options.

Zyrtec (cetirizine) is available in a 10 mg tablet as well as generics. Claritin (loratadine) comes in a 10 mg tablet or chewable tablet. Children’s Claritin comes in a liquid or a chewable 5 mg tablet. Allegra (fexofenadine) comes in a fairly large 180 mg tablet or a Children’s strength 30 mg tablet. Generics for both Claritin and Allegra are also plentiful.

What other anti-histamines have you used in your patients? Do you think they work as well as the prescriptions like Apoquel? Let me know in the comments.

Part 3 is coming soon!


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