Benzocaine Toxicity in Dogs

Your puppy is teething, and you'd do anything to mute that pitiful whimpering and make her feel better. You've tried chilling a plastic toy to try to numb the pain, but it's not helping much. Is it time to reach for that tube of Orajel you used when you had a toothache?

Dog under blanket
Benzocaine Toxicity in Dogs
credit: Lindsay_Helms/iStock/GettyImages

Benzocaine

The topical anesthetic benzocaine helps block nerve signals to alleviate pain. In dogs, it is sometimes used to treat gum inflammation, earaches, skin conditions, and pain caused by trauma to various parts of the body. The drug is formulated in a cream or ointment form.

Orajel for dogs

If your dog is in pain, don't reach for that tube of human-grade Orajel or another over-the-counter mouth pain reliever containing benzocaine. Anbesol for dogs is also not recommended.

Rather, get a prescription from your vet for a dosage that is appropriate for canines. The prescription should be filled by a compounding pharmacy that has experience in formulating topical medications for veterinary use.

Benzocaine isn't just used for dog tooth pain relief. Antipyrine and benzocaine for dogs is another formulation of the drug that is used to treat ear pain. But, again, when it's prescribed for your pup, it should be made explicitly for canines rather than humans.

Drug sensitivity and allergies

Benzocaine formulated for dogs is generally safe, but some dogs may be more sensitive to it than others. The most common side effect is skin irritation in the area in which the cream is spread. Dogs that are highly sensitive to the drug could develop a more wide-spread, serious rash. Wheezing and vomiting may indicate a more serious allergic reaction and the area where benzocaine was applied should be cleaned, and your veterinarian contacted.

A serious side effect

When dogs are treated with human-grade Benzocaine, it increases their risk of developing a serious blood disease called methemoglobinemia, a kind of anemia. This rare condition dramatically reduces the amount of oxygen carried through the blood. This is life-threatening and could result in death.

One sign of the condition is that blood turns a brownish color indicating far too little oxygen is circulating. Weakness, rapid breathing, and vomiting are also signs of methemoglobinemia. In addition to being exposed to toxic amounts of benzocaine, dogs can develop the condition if they ingest too much acetaminophen, which is the active ingredient in Tylenol or ibuprofen.

Methemoglobinemia is not just a concern for dogs. In 2018, the U.S. Food and Drug Administration warned that oral drug products containing benzocaine should not be used to treat infants and children younger than two years because of the risk of methemoglobinemia.

Safe use of benzocaine

Because benzocaine is meant to be used topically, it can be toxic if a dog eats a product containing the drug. Generally, when applied to the skin or gums, a small amount of the drug is absorbed. By ingesting a tube of it, your dog may be exposed to a dangerous amount. Store it in an area inaccessible to your dog, such as a high cupboard or medicine cabinet.

It is also important to keep your dog from licking areas where benzocaine was applied as much as possible. An Elizabethan collar can help keep him from accessing the area treated with benzocaine.

Alternative ways to ease the pain

Many pain relievers in your medicine cabinet are not safe for dogs, particularly in strengths appropriate for humans. Non-steroidal anti-inflammatory drugs like aspirin and ibuprofen can be toxic to dogs depending on the dose. Instead, several NSAIDs have been developed specifically for dogs. These include carprofen, deracoxib, firocoxib, and meloxicam.