Many pet owners are regularly searching for alternatives to pharmaceuticals and insecticides, so more natural remedies like essential oils are commonly discussed. Peppermint oil is one such essential oil that is sometimes recommended for use in pets, specifically for killing fleas. Despite its popularity though, peppermint oil has very little scientific research for use in animals or for killing fleas and it can actually pose a major risk to your pet.

What Is Peppermint Oil?

The peppermint plant, Mentha x piperita, is a cross between the spearmint and watermint plants. It is a fragrant, green-leafed plant that is very easy to grow. The taste of peppermint is often described as peppery, and it is widely used in foods, beverages, and for a variety of health purposes in people.

Peppermint oil is an essential oil that is obtained from the leaves of the peppermint plant. It is not the same as peppermint extract, however, since the oil is much more concentrated. This concentrated, fragrant oil contains special components of the peppermint plant that are called terpenes and flavonoids. Some of these components have shown to be beneficial to both people and pets, and are also found in many other plants. The specific terpenes and flavonoids that are found in peppermint oil include menthol (21.68%)1, menthone (31.76%)1, menthofuran (7.08%)1, eucalyptol (4%)1, linalool (2.59%),1 limonene (0.6%),1 and various others in lesser amounts.

Warning

Peppermint oil should never be fed or administered to pets by mouth, especially to cats. It can cause a variety of issues including vomiting, diarrhea, seizures, paralysis, and even kidney failure.

Is Peppermint Oil Safe for Pets?

Peppermint oil is considered to be toxic to cats and may also cause problems for dogs. Despite this, some products designed for dogs contain peppermint extract or very small amounts of peppermint oil at safe levels. These products are typically used for flavoring or for gastrointestinal benefits2 and are based primarily on studies done in rats3. Very little scientific research has been done on the safety of peppermint oil use in pets, so it is not typically recommended to be used, especially at high concentrations, due to the lack of available information.

According to the Pet Poison Hotline, cats are especially at risk for peppermint toxicity since they metabolize differently than dogs. Cats have been reported to experience drooling, vomiting, tremors and seizures, difficulty walking and breathing, stomach ulcers, low body temperature, low blood pressure, rear limb paralysis, skin irritation, and even liver and kidney failure depending, on how the oil was used. Dogs are potentially less sensitive to peppermint oil than cats, but large amounts of concentrated peppermint oil could still be dangerous for canines.

Does Peppermint Oil Kill Fleas?

Peppermint oil has been shown to potentially be effective at killing or repelling a variety of insects including some mosquitoes, beetles, houseflies, midges, lice, cutworms, Argentine ants, whiteflies, aphids, and diamondback moths. Products containing peppermint oil alongside other essential oils have also shown some effectiveness in killing fleas, but it is not known whether it was the peppermint or the other essential oils in the product that caused it to work.45

Since peppermint oil contains a small amount of linalool (2.59%) and limonene (0.6%) and these components have been shown to be effective in killing fleas6, peppermint oil may kill fleas in large, concentrated amounts. This is not helpful to pets though, since large, concentrated amounts of peppermint oil can be toxic to them. A small, potentially safe amount of peppermint oil will not kill fleas and giving more peppermint oil to provide more of these components is dangerous to your pet. It is not worth the risk of poisoning your pet by using peppermint oil when other flea killing options exist that are much safer to use.

How Is Peppermint Oil Used?

Peppermint oil has been used topically, orally, and diffused into the air. These methods of delivery all carry their own risks, so there is not one method that is necessarily safer than the other, especially to cats. Topical application can cause skin irritation and be absorbed into the body causing more serious issues; diffused oils can cause respiratory distress; and oral oils can result in organ failure, vomiting, diarrhea, and other issues.