Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066



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11.3 MG, 28.3 MG, 68 MG, 136 MG



In older times, flea control was a very labor-intensive process involving sprays, dips, foggers, yard treatments, powders and more. As technology progressed, products became safer and more convenient culminating in a whole “next generation” of products starting with Program® in 1995, and Advantage® and Frontline® not long after. For the first time, flea control could be performed once a month in the simple form of a chewable tablet or smear of topical oil. These products represented a revolution in flea control but the revolution did not stop there. Today parasite control has proliferated into dozens of products controlling different combinations of organisms and with many administration options.

Afloxolaner was released by Merial Animal Health in 2014 as a beef-flavored chewable prescription medication called "Nexgard®."  A related product called "Nexgard Spectra®" is available in Europe. Nexgard Spectra combines afoxolaner and milbemycin, an anti-worm medicine, so as to provide nearly total parasite protection in one product but this version of Nexgard is not presently available in the U.S.

A valid patient-doctor relationship is required to obtain a prescription for afoxolaner. Nexgard kills fleas and ticks only and has no activity against intestinal worms or heartworm. There are four ticks of concern in the U.S. (see our tick product comparison chart for more details) and afoxolaner will kill all of them plus several additional tick species not on the official approval label. As for fleas, afloxolaner kills fleas before they are able to lay eggs so that a flea sterilizer is not necessary in the tablet.


Afoxolaner lasts one month and can be used in puppies/dogs 8 weeks of age and older so long as they weigh at least 4 lbs. It should not be used in cats.

Afoxolaner can be given either with or without food.


The possible side effects reported include nausea/vomiting (4% of dogs), diarrhea (3% of dogs) dandruffy coat (3% of dogs), lethargy (less than 2% of dogs) and appetite loss (less than 2% of dogs). Most dogs that exhibited one of these side effects only exhibited them after the first dose and not with subsequent doses.

If a dog vomits within 2 hours of administration of a Nexgard tablet, a new tablet should be given. If vomiting occurs after 2 hours, re-dosing is not necessary.



There are no known drug interactions with afoxolaner.



Afoxolaner has not been evaluated in pregnant or nursing animals so it is recommended not to use afoxolaner in this situation.

Afoxolaner kills fleas by causing an over-stimulation of the insect nervous system. This leads fleas to be extra active just before they die; this increase in activity can lead the fleas to be more visible.

The manufacturer recommends caution in dogs with known seizure disorders. Muscle tremors and seizures can occur in animals with no prior history of such as well.

If a monthly dose is skipped, fleas and ticks will be able to complete their life cycle freely. Do not double up on the next dose, though; simply, give the afoxalaner when you remember to do so.

Store at room temperature in the sealed container provided by manufacturer.

For more information on afoxolaner visit:

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Page posted 3/9/2023