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The Hazards of Mixing Up Flea and Tick Medication

The Hazards of Mixing Up Flea and Tick Medication

Have you ever been confused about which flea and tick medication to give your pet? If so, you're not alone. We often get asked this question by our customers at the front desk of our vet clinic, and we wanted to put together a quick blog post with some helpful tips. There are a lot of different products on the market these days for both types of pests, so it's always best to ask your veterinarian for advice. But here are some general guidelines: if your dog or cat has fleas but no ticks, use an anti-flea product; if they have both fleas and ticks (or only ticks), use an anti-tick product; if they have neither flea nor tick issues but live in areas where there are ticks, use a product that is labeled for both fleas and ticks. If you have a cat, always use products specifically formulated for cats because they have different sensitivities!

Flea and Tick Medications: Mixing Dangers for Cats

While cat-formulated products are typically safe for dogs, dog formulations can be very dangerous for cats. The active ingredients in most dog flea and tick medications are not safe for cats at all, and using a dog product on a cat has been associated with a number of serious health problems. If you have a cat but your pet also lives outside with dogs who may bring pests into the house, it's extremely important to keep them separated when administering any type of treatment!

How to Find the Right Combination?

Assuming you have a pet with both fleas and ticks, what do you do about it? If your vet says your pet can handle both kinds of medication, ask him or her if they recommend using the same product for both, or using two different ones. Using two different products at once is fine as long as they are compatible (that means in the same family). Examples include Frontline Plus and Advantage Multi.

Two in One = Safe!

Combinations to Know: Oral Flea Treatments

There are also some commonly-used products that can be used for both fleas and ticks, such as oral medications. One example is Nexgard (generic name: afoxolaner), which is a spot on medication that is easy to use and has virtually no risk of toxicity in animals or humans. Another good one to know about is Bravecto (generic name: fluralaner), an oral chewable medication taken every three months instead of monthly like most other treatments. If you have a dog, we recommend either Nexgard or Bravecto – give us a call for more information!

Combinations to Know: Flea Collars

Flea collars can often treat ticks too, but there's less data available on the safety and effectiveness of collars compared to other products. The material of a flea collar is a big concern – many products contain hazardous chemicals which can be absorbed into the skin and potentially cause health problems after prolonged use. For example, both flea and tick collars contain chemicals known as pyrethroids, which are potentially toxic to cats. If you must use a flea or tick collar on your cat, don't leave it on for long periods of time! Only put it on them when they go outside or there might be pests in the house.

Combinations to Know: Flea Shampoos & Conditioners

Another option for treating many types of pests is with a shampoo or conditioner that also contains anti-flea/anti-tick medication. These are fairly common, but most have dangerous ingredients so we recommend using them with caution. We do not recommend bathing pets every month since this washes off treatments meant to last much longer! In general, if you want to use a topical treatment on your pet's skin (flea/tick shampoo, flea collar, etc), it's best to avoid oral medications since they will cancel each other out.

Combinations to Know: Heartworm Medication

Heartworm treatments can treat ticks and fleas, but they don't repel them. There are some oral medications that can prevent both heartworms and fleas/ticks at the same time, but only once every 30 days. Some of these products also come in a topical version instead of an oral one which makes them even safer for your pet!

The Dangers of Mixing Flea and Tick Treatments!

Overall, it's best to be cautious. Even though some products are safe when used alone, they can become more dangerous when combined with another type of medication. Our veterinary staff has seen firsthand the dangers of accidental ingestion of these combination pills so please call us right away if you suspect your dog or cat ingested one! After all, prevention is always better than cure!

Flea and Tick Medications: Mixing Dangers for Dogs

As we mentioned, dog formulations are far too risky for cats, but what about dogs? Well…it depends on the individual! Some dogs can handle both fleas and ticks just fine without any negative side effects, but if your dog experiences issues such as vomiting or diarrhea with tick treatment then it's best to ask your vet before trying anything else. Even if there aren't any obvious symptoms that something is wrong, it's always safest to avoid using two treatments at once unless they are specifically compatible.

Remember, no matter what product you use on your furry friend, make sure to keep them separated from cats (and all other pets!) until the treatment is fully dried! If your pet does not have both fleas and ticks but lives in an area with a lot of pests or likes rolling around outside, be extra careful about using any products that contain more than one active ingredient at once. Double check the label before applying anything new, and if you're not sure don't hesitate to ask us for help!

Combinations Not to Use:

Generally, it's not safe to give pets both oral and topical medications at the same time. This is because when pet owners try this method, they often don't realize that they gave their dog (or cat!) the wrong medication! For example, some flea treatments are in pill form and can be deadly if given to cats. Even mistaking a cat treatment for a dog one could lead to serious problems . Always ask your vet before giving your pet anything new! If you aren't sure what type of product to use on your pet, call us for help! By weighing the pros and cons of each situation with our veterinary staff there's no reason why you can't have best protection all members of your family.


Mixing up flea and tick medication can be dangerous. Be sure to use the right product for your pet's needs. Ask a veterinarian if you're not sure what type of treatment is best for your furry friend!


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