Bravecto is a relatively new product released in 2014 which can provide long-lasting protection from fleas and ticks (black-legged tick, American dog tick, brown dog tick and lone star tick), or treat existing infestations. It contains the active ingredient fluralaner, a type of isoxazoline which maintains protection for 12 weeks, meaning you only have to use the medicine as a preventative roughly once every 3 months. There is some discussion about its safety which we will explore from an unbiased perspective later in the article.

How does it compare to Comfortis and Capstar?

Comfortis and Capstar are two other popular flea treatments. Unlike Bravecto, Comfortis does not kill ticks and needs to be given every month, and Capstar is not effective as a flea preventative. Which medicine you choose will come down to personal preference and how well your dog tolerates each of them.

Safer Treatment for Fleas & Ticks

As you may have read online, many owners believe Bravecto has severely harmed their dog. As a safe alternative, this shampoo kills fleas, ticks, and mange mites on contact.

What’s The Correct Dosage?

Note: Bravecto is a prescription-only medicine, speak to your vet before use. It should not be purchased or used unless a licensed vet has given you permission to do so.

Because fluralaner remains active against fleas and ticks for 12 weeks, you will only need to administer Bravecto once every 12 weeks (or once every 8 weeks if you require protection from lone star ticks). The minimum target dose of fluralaner is around 11.4 mg/lb, but different boxes are made for different sizes of dog to make dosing easier. See the table below for the amount of tablets you should give to your dog per dose.

Weight of dog (lbs)

Tablets to use per dose

4.4 – 9.9One yellow box tablet (112.5 mg)
10 – 22One orange box tablet (250 mg)
22.1 – 44One green box tablet (500 mg)
44.1 – 88One blue box tablet (1000 mg)
88.1 – 123One pink box tablet (1400 mg)
Over 123Use an appropriate combination.

 Color-coded Bravecto
If your dog weighs more than 123 lbs you will need to give him an appropriate combination of chews to reach the desired dose. Which tablets you use will depend on the size of the dog being treated. For example, if your dog is 150 lbs, you could give him two blue box chews per dose, which would cover dogs weighing anywhere from 88.2 to 176 lbs.

Because the chews are palatable, most dogs will take them immediately, but if not, offering them with food will often help. Giving the chews with food is recommended in any case to reduce the risk of vomiting. If you still have difficulties getting your dog to take the medicine you can try using GREENIES pill pockets.

How quickly does it work?

Fluralaner takes effect quickly and begins killing fleas (adult and juvenile) within 2 hours, and ticks within 12 hours.

Note: A dog weighing 30 lbs could be protected from fleas or treated for several types of tick by taking one tablet from the green box every 12 weeks.

Is It Safe?

Fluralaner (the product’s active ingredient) is approved by the FDA for use in dogs. It should only be given to dogs who are both 6 months of age or older and 4.4 lbs or heavier. In trials it has been given alongside anthelmintics (a group of antiparisitic drugs which includes Panacur), antibiotics, steroids and vaccines without causing any adverse reactions. It has also shown to be safe for pregnant and nursing animals.

Reports on the safety of fluralaner:

The following links contain important information about the safety of fluralaner, including investigations into popular social media rumors.

“Does Bravecto Kill Dogs?” Facebook Group – A group on Facebook where owners report possible side effects their dog has experienced as a result of Bravecto. This evidence is anecdotal, but should still be taken into consideration.

CVM ADE: Report of side effects – This document contains a list of reported side effects to help you make an informed decision about treatment.

Investigation into Bravecto by Snopes – Snopes is a website which investigates and puts facts to rumors. They have investigated reports circulating social media about the dangers of fluralaner and have deemed these reports to be unproven.

Considering the reports written by owners about bad reactions, it is wise to practice caution and speak about any concerns with your vet. If you notice your dog losing his appetite, throwing up food, becoming lethargic, or developing symptoms which mimic a urinary tract infection (e.g. urinary retention or incontinence and cloudy urine), we recommend speaking to your vet and possibly testing kidney and liver values just to be safe.

FDA Status: Fluralaner is FDA-approved for veterinary use under application number 141-426.

Safety Guidelines

To use Bravecto correctly please follow these guidelines:

  • Seek advice from your vet before beginning treatment
  • Even though there are no listed contraindications and the product does not interact with the most frequently used veterinary medicines, be sure to tell the vet about any medical conditions your dog suffers from, as well as any other medicines and supplements you are treating him with.

  • Only give to dogs who weigh at least 4.4 lbs and who are at least 6 months old
  • Sign up for reminders so you don’t forget when the next dose is due
  • Give each dose of Bravecto with food to reduce the risk of vomiting
  • Watch your dog in case of a bad reaction and report any side effects to the vet
  • Consider monitoring kidney and liver function

The “reminders” service is free and highly recommended. When you only give the chews once every 12 weeks it can become difficult to remember when the next tablet is due, so these alerts can come in handy.

What Is It Used For?

This product has the following uses:

  • Flea prevention

  • It can provide protection from fleas for around 3 months at a time.

  • Treat tick and flea infestations

  • It works to kill adult fleas 2 hours after the tablet is given and remains effective for 12 weeks. It can also kill black-legged, brown dog and American dog ticks for 12 weeks, but loses its effectiveness against lone star ticks after 8 weeks (about 2 months).

Fluralaner is not an effective treatment or preventative for worms. To prevent or treat cases of worms you should use a deworming medicine such as fenbendazole. Fenbendazole (the active ingredient of Panacur) is a type of broad-spectrum anthelmintic which should not cause any adverse reactions when given alongside fluralaner.

Side Effects

Bravecto may cause these adverse effects:

Most Common

  • Vomiting (by far the most common)
  • Loss of appetite
  • Increased thirst
  • Weight loss
  • Lethargy
  • Diarrhea
  • Itching
  • Gas


  • Edema
  • Changes in behavior
  • Increased thirst
  • Blood in stools
  • Hyperemia
  • Seizures

More side effects (some very serious) have been reported by owners on Facebook and on various forums.

Contact the vet if you notice your dog becoming lethargic, losing appetite/throwing up food and developing symptoms similar to those seen with urinary tract infections, or if your dog experiences any serious reactions to the drug. You should also report these to Merck Animal Health on 1-800-224-5318. In cases of overdose always seek veterinary attention, as dogs who receive an overdose can experience blood in stools, seizures (particularly if they are predisposed to seizure activity) and an even higher chance of vomiting.



Dr. M. Fox