Fipronil - What You Need To Know | Veterinary Prescriber
Fipronil - What You Need To Know
Fipronil is one of the most common ingredients in non-prescription flea and tick treatments for cats and dogs.
What is Fipronil?
Fipronil is a type of chemical known as a parasiticide, ectoparasiticide or pesticide. It has insecticide effects (that is, it kills insects) and acaricide effects (that is, it kills acarids such as ticks). It works by interfering with nerve activity in the insects and acarids that come into contact with it. This leads to uncontrolled activity of the central nervous system and death in insects and acarids.
How is Fipronil used?
Products containing fipronil are used to control fleas and ticks, which are parasites that can infest cats and dogs. The most common fipronil products are known as ‘spot-ons’. These are liquid formulations that are applied in one or more spots on the neck and back of the animal. Fipronil is also available as a spray. After application, fipronil spreads over the surface of the animal’s skin and accumulates in the sebaceous glands from where it is slowly released to keep the hair and skin coated for several weeks. Through this mechanism, fipronil kills the fleas and ticks that come into contact with it on the animal’s body.
Fipronil combined with S-methoprene
Most of the spot-on flea and tick treatments on sale without a veterinary prescription either contain fipronil alone, or fipronil together with S-methoprene, a chemical that interferes with the development of immature stages of fleas. S-methoprene kills flea eggs and prevents flea larvae and pupae from developing.
How effective is fipronil on fleas and ticks?
Any product that is claimed to treat flea and tick infestations in cats and dogs is classed as a veterinary medicine. This means that the companies that market the products have to prove to the veterinary medicines regulator (which in the UK is the Veterinary Medicines Directorate) that the product meets regulatory standards for efficacy and also safety and quality. Efficacy relies on correct use of the product, so it is crucial to follow the instructions for use that accompany the product.
How can you tell if a flea and tick treatment contains fipronil
Flea and tick products containing fipronil or fipronil plus (S)-methoprene have been around for a long time, and there are now very many brands on sale with and without a veterinary prescription. The brand name of the product will be very prominent on the packaging, but the active ingredient names will also be listed on the packaging and in the package leaflet. You should be able to find these easily, although they will be in much smaller lettering than the brand name.
How do fipronil products differ from other flea and tick products?
There are dozens of prescription and non-prescription products on the UK market for treating flea and tick infestations in cats and dogs. They contain one or more active ingredients out of a range of over 20 different substances - fipronil is just one of these. There is also a variety of formulations, not just spot-ons and sprays, but collars and tablets too. With this variety comes some key differences in the ways that these products work - for example:
Some products, like those containing fipronil, work by remaining on the cat or dog’s skin where they come into contact with parasites.
Others are absorbed into the animal’s body after being given as a tablet or applied as a spot-on (from where the active substance enters the animal’s bloodstream. The way these work is that parasites are killed after biting and taking a blood meal.
Some spot-on and collar products on general sale are not classed and regulated as veterinary medicines. These are products that contain a repellent (e.g. diethyltoluamide [DEET], margosa [neem oil]). These only claim to repel ectoparasites. They do not fall under the definition of a medicine and so are not regulated by the veterinary medicines regulator. As a result, no proof of their effectiveness is required.
Confusing?
The flea and tick product market is enormous. There are so many brands, formulations and combinations of ingredients out there that even veterinary professionals can find it difficult to keep up with it all. It is easy to find information on an individual product by looking it up in the Veterinary Medicines Directorate’s Product Information Database, or the NOAH Compendium - but if you really want to get your head around what’s available and be able to compare products, you will struggle without Veterinary Prescriber’s Parasiticide Guide and explanatory module “Making sense of flea and tick treatments”.
Are fipronil products safe?
As veterinary medicines, the safety of flea and tick products to the animals being treated and humans handling the products is rigorously tested and continuously monitored. The widespread availability of pet parasiticides is a reflection of the fact that when they are used correctly they are generally safe for pets and for humans who handle the products. However, it is now becoming apparent that we need to be more mindful about how much we use these products because of evidence showing that pet parasiticides can end up in the environment, where they may harm wildlife.
More about Veterinary Prescriber
Veterinary Prescriber is an independent medicines information resource for veterinary professionals. Our mission is to educate veterinary medical professionals about the various drugs and treatments at their disposal, and the changing landscape around those treatments within the wider realm of veterinary medicine, In short, to keep a wide range of veterinary medical professionals up to date on all aspects of veterinary medicines use, and we accomplish this mission through two main online archives of information.
First and foremost is our Virtual Veterinary Medicines Academy, or ‘VVMA’, which is accessible via subscription. In the VVMA you will find a wide variety of learning modules covering all aspects of veterinary medicines, as well as our independent critical reviews of medicines which can help prescribers make the best treatment choices for their patients. The VVMA also includes monthly ‘Medicines News’ articles to help you keep up to date with the latest developments on medicines and a range of other helpful resources - product guides, comparative tables, and medicines Q&As, for example. You can also find a wide range of articles on various aspects of veterinary medicines use on our blog page, which is free to access.