We have received questions from a few of our clients about about the safety of Trifexis (a popular oral flea, heartworm, and intestinal parasite control) due to online blogs and media reports. We understand the outpouring of concern as the blogs and media have noted that reactions even include death. Since it can be difficult to differentiate between what is proven data and what is anecdotal, we want you to know that to date, there has been no confirmed link to any deaths caused directly by Trifexis. Even the most recent media report by ABC 10 news in San Diego (August 13, 2014) had cases where we would find it unlikely that Trifexis was the cause of death, even with the limited information that they provided. Two of the possible deaths were in 12 year old golden retrievers who were apparently healthy. Over the years, seeing this scenario played out again and again, we frequently see older dogs suddenly die, often from undetected cancer. This is one of our motivations for starting our Pet Cancer Screening Day every May. The third example is of a young puppy who died of severe cardiac disease. The heart disease is unfortunately what killed this puppy, not the Trifexis (Trifexis doesn’t cause heart disease).

The most common side effect of Trifexis, which occurs in approximately 10% of dogs, is vomiting. Giving the medication with food can help to decrease this risk. What we recommend to our clients when giving the medication is to record the time they give the pill and then watch their dog closely for the next hour.  If they vomit and it has been more than 1 hour, the medication has been absorbed and there is no need to follow up.  If it has been less than 1 hour, the manufacturer recommends to give another full pill.  However, we do not recommend redosing right away.  If your pet is miserable because they are full of fleas, go ahead and give another ½ dose that night and the remaining ½ in the morning.  If they are not currently infested with fleas, we recommend waiting 3-5 days, then try giving the medicine again with a large meal.  If they vomit again, this is probably not the medicine for them.

However, there are some pets that should not be on this oral flea medication. If your pet has an underlying seizure disorder, or is prescribed a high-dose Ivermectin treatment, usually for a mite infestation (Demodex or scabies), they should not be on Trifexis or Comfortis.  There is potential for a serious drug interaction that can occur causing tremors, seizures and even death.  

Another note of importance is that Trifexis and Comfortis are FDA regulated drugs, therefore, they are not available from ANY pharmacy other than a veterinarian.  If you find this medication online or at another local pharmacy, the medication has been illegally sold, either under the table by veterinarians or imported from overseas factories where the FDA does not regulate the drug. The company cannot guarantee these drugs due to safety concerns with transportation, how many hands it has passed through, or whether it is even the same product. This is an important question for the owners of the dogs who are potentially having severe side effects. Where were the drugs purchased? If it wasn’t through your veterinarian, who knows where those meds were obtained and what is in them.

We discovered that more than 50 million doses of Comfortis and Trifexis have been prescribed since 2003, and the number of side effects that have been reported are approximately 2,000.  More investigation into these allegations definitely needs to be explored, however, we still feel that this is a safe medication.

If you suspect that your pet is having a reaction to this drug or any other drugs, please let us know so that we can consider switching medications. As with any oral medications, side effects are possible. However, fleas are also toxic to your pet’s health and we strongly recommend some form of effective year round flea prevention.

If you have any questions, please feel free to call us.

–The Coastal Animal Hospital Team