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Combining Flea Treatments: What You Need to Know

Is It OK to Cross The Streams?

By James Donatelli. January 01, 2011 | See Comments

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Combining Flea Treatments: What You Need to Know

Mixing medication without proper supervision is always a bad idea, even when it comes to your pet's flea and tick medications. Here are a few things you should know before experimenting.

We all want to protect our pets from fleas and ticks, and our homes from flea infestations. There are many great products out there right now that make doing so easy, like spot ons that kill adult fleas and ticks and stop the growth of new fleas. But what if a medication no longer seems to be working well or you want extra protection for your pet—is it safe to add a second flea and tick medication?

Every pet is different. The right product(s) for one pet might not be right for another pet, which is why having guidelines is important in making the best choices for your best friend. Below are some tips to help you protect your pets.  

How to Find the Right Combination

Always read product labels, particularly the drug interaction sections, if you intend to combine products, and check with your vet before combining products.

Products that only treat fleas are generally safe to combine with products that only treat ticks. But similar to how some people can have different reactions to combinations of medication—pets can react differently to combinations of medications. Your pet might have special medical conditions that only a veterinarian would know. Again, consult your veterinarian before combining medications.

Combinations to Know: Oral Flea Treatments

Either Capstar or Comfortis can be combined individually with a variety of other flea and tick medications including one of the following: K9 Advantix II, Frontline Plus for Dogs, Advantage II for Dogs, Revolution (for dogs), Pet Armor for Dogs, Advantage Multi for Dogs, Frontline Top Spot for Dogs, Sentinel, or Farnam Bio Spot for Dogs. Capstar will knock out a flea infestation quickly and is over the counter. Comfortis requires a prescription and works to kill adult fleas for a month.

It’s not usually recommended to use more than one oral flea medication at the same time. However, Comfortis and Capstar can be combined. Another exception is Sentinel, which doesn’t kill adult fleas, so it can be combined individually with either Comfortis or Capstar.

Combinations to Know: Flea Collars

Some flea collars, like Preventic, are generally safe to combine individually with one of the following: Frontline Plus, Revolution, Pet Armor, Frontline Top Spot or Farnam Bio Spot, K9 Advantix II, Advantage II, Trifexis, Interceptor, Certifect, or Advantage Multi. When used in conjunction with one of the above medications, Preventic collars have been shown to be effective for flea and tick prevention, particularly tick prevention. A good time to use a collar like Preventic with your normal preventative is if you're going for a deep woods hike with your dog. You can remove the collar after the hike! Talk to your vet before combining a Seresto flea collar with any other medications.

Combinations to Know: Heartworm Medication

If you’re concerned about combining heartworm medication with flea and tick products, Heartgard is a good choice, as it doesn’t target fleas or ticks. This means that it can usually be safely combined with other flea and tick medications. However, Heartgard is not safe to combine with a flea and tick medication if that second medication also contains heartworm medication.

Combinations Not to Use

Here are some examples of common medications that should never be combined: Frontline Plus should not be combined with Advantage II; Advantage Multi should not be combined with Revolution; with the exception of Capstar or the Preventic collar, Advantage Multi should not be combined other medications. Frontline products should not be used in conjunction with Advantage or Advantix products.

Your pet shouldn’t receive a flea bath if they have recently been introduced to another flea or tick treatment (for example, if your pet was treated with a spot on in the past month). If your pet is given a flea bath, they shouldn’t receive another medication for a few days after—Capstar is a more flexible, reliable alternative to flea baths.

Flea and tick treatments that are applied to the surrounding environment—either outdoors or in your home, usually won't conflict with medications given directly to your pet. Just try to be mindful of where your aiming the treatment (don’t spray your pet)!

Some Final Tips

Using more than the recommended dosage of any individual medication is never advisable. This is not limited to prescription flea and tick medications. In fact, over the counter medications can present greater risks when more than the recommended quantity is given to your pet. In particularly bad flea or tick infestations, certain products recommended for monthly use might be used every three weeks under the advice and supervision of your vet.

Aside from any of the above exceptions, it is not recommended to combine medications that are designed to target the same problems (in essence, “doubling up” on certain types of products). For example, it is not safe to use more than one spot on flea and tick medication during the time that the product is still active, more than one oral flea and tick medication, or more than one product that contains heartworm medication at the same time. Consult your veterinarian if you’re not sure about a medication choice.

More Flea and Tick Control Advice

The Flea Life Cycle
How to Kill Fleas in the Yard
Flea and Tick Season: When to Use What Treatment
How Do Flea Collars Work?
Oral Flea Control: Flea Pills For Dogs And Cats

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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