Products based on isoxazoline compounds, which are used to prevent and treat fleas, ticks and mites (Bravecto, Bravecto Plus, Nexgard, Simparica, Simparica Trio, Credelio, Revolution Plus), are becoming increasingly popular. Many traditional veterinarians strongly recommend the use of this class of isoxazoline-based products. Unfortunately, as the number of animals given these products has increased, so has the number of pet owners reporting neurological and other side effects.
What are the possible side effects when using Bravecto, Nexgard and Simparica oral insecticides?
Neurological side effects or adverse reactions can range from barely noticeable to serious. Adverse reactions to these compounds appear to affect animals randomly, although those with certain chronic diseases, young and old animals, and animals that are immunocompromised or have a genetic mutation in the MDR1 gene are at greater risk.
A few adverse reactions that dog owners notice include:
- Seizures (like epilepsy)
- Disorientation
- Staggering or unsteady gait
- Sensitivity to touch
- Abnormal vocalizations
- Urinary or fecal incontinence
- Aggressiveness
- Personality changes
- Death
Side effects can occur immediately after application, but there are also cases where pet owners have noticed these reactions days, weeks or even months later. Sometimes reactions do not occur until multiple doses of Bravecto, Nexgard, or Simparica oral insecticides have been administered.
Other side effects that have been reported include:
- Liver failure
- Kidney failure
- Dry eye
- Blood clotting disorders
- Internal bleeding
- Skin diseases and itching
- Vomit
- Diarrhea
- Loss of appetite
- Salivation
What should you do if you believe your dog is having an adverse reaction?
First of all, take your pet to the vet immediately if you believe they are having an adverse reaction.
Many pet owners like that some of these products come in pill form, which makes them easier to administer. The problem with this type of administration (oral administration), of any drug, is that once something is introduced into the animal's body, it is not easily removed unless the patient is brought in within an hour of administration.
In an emergency where a pet has a reaction to spot on ampoules, collars or other topical flea or tick product; it is important to thoroughly rinse, i.e. bathe the animal in order to remove as much of the poison as possible. With oral insecticides, we don't have that option!
These animals need to undergo liver and kidney detoxification, and then we provide them with symptomatic support. There is a helpful book "Yin & Yang Nutrition for Dogs", you can use a liver support diet, liver detox, blood tonic and kidney support diet. I also recommend the following nutritional supplements:
- Zeolite
- CBD oil for dogs (2.5% up to 10kg // 5.5% up to 25kg // 11% from 25kg and more)
- Silymarin 50-100 mg per 11 kg twice a day
- N-Acetylcysteine (NAC) 500mg twice a day for 2 weeks, then once a day for 2 weeks
- Chlorella 25mg twice a day for 3 weeks
- Liposomal glutathione 100mg per day for one week
- Curcumin 100mg once a day for one week
- Broccoli sprouts 100mg once a day for one week
- Gamma-aminobutyric acid (GABA) 100mg once a day for one week
- Add asparagus and dandelion or dandelion leaves to your diet. Dark green leafy vegetables such as kale, beet tops and spinach can be beneficial
- Epsom salt/bicarbonate baths to flush out toxins
Some dog owners continue to use these dietary supplements for long periods of time without adverse effects if the pet continues to have symptoms.
Be sure to report the incident to the FDA and the manufacturer!
It is also important to report adverse reactions to the FDA and the manufacturer of the drug used. The FDA continues to monitor reports of adverse events associated with animal drugs and encourages pet owners and veterinarians to report such events. You can do this by reporting to drug manufacturers, who are required to report this information to the FDA, or by submitting a report directly to the FDA.
To report side effects, suspicions and adverse reactions related to these products and/or to obtain a copy of the Safety Data Sheet (SDS) or technical assistance, contact the respective manufacturers at the following telephone numbers:
Merck Animal Health (Bravecto, Bravecto Plus): 800-224-5318
Elanco Animal Health (Credelio): 888-545-5973
Boehringer Ingelheim (Nexgard): 888-637-4251
Zoetis (Simparica, Simparica Trio, Revolution Plus): 888-963-8471
If you prefer to report directly to the FDA or would like additional information about reporting adverse events related to veterinary drugs, see How to report side effects and problems with veterinary drugs and devices.
Pet owners and veterinarians who have additional questions can contact AskCVM@fda.hhs.gov or call 240-402-7002.
Here you can find a warning about possible side effects from the FDA:
2021 – Fact Sheet for Pet Owners and Veterinarians about Potential Adverse Events Associated with Isoxazoline Flea and Tick Products
2020 – Fact Sheet for Pet Owners and Veterinarians about Potential Adverse Events Associated with Isoxazoline Flea and Tick Products
2019 – Animal Drug Safety Communication: FDA Alerts Pet Owners and Veterinarians About Potential for Neurologic Adverse Events Associated with Certain Flea and Tick Products
What are the long-term consequences of using Nexgard, Bravecto and Simparica oral insecticides?
Some animals manage to recover completely, while others have side effects forever. By using CBD oil (organic and lab tested) and the recommendations described above, it is possible to improve the quality of life for dogs with side effects, but it is important to remember that there is no magic cure for everything. Reactions to preparations can be very individual and it is important to carefully monitor and supervise your animal during the application of any product.
These are just general guidelines, and each case is unique. I recommend that you consult with a veterinarian who is familiar with the side effects of these preparations and can provide an individualized treatment plan. This is often not the same veterinarian who recommended oral insecticide to your pet, because he will most often claim that the side effects are not related to the preparation he recommended!
If you need support or are interested in the experiences of the wider community of dog owners, you can find them in these groups:
Bravecto Nexgard Comfortis Simparica Trifexis & others Do They Kill Dogs?
For experiences and advice about CBD oil, join this group:
Woff Woff :: Dog Dream Factory
Sometimes you need to protect your muzzle from "protection" products! Keep that in mind when choosing preparations against ticks and fleas. Even before oral insecticides, we successfully protected dogs against these pests.
