We asked our resident vet for some answers, so you can make the best decision for your pet.
What is fipronil and how does it work?
Fipronil is a widely used insecticide that kills fleas and ticks by targeting their nervous system, causing paralysis and death.
It works by spreading through your pet’s natural skin oils, providing targeted protection across the coat. This makes it effective for controlling active infestations and reducing biting and irritation.
Fipronil is used in many flea treatments, including the Bob Martin CLEAR/CLEAR PLUS range, as well as other well-known products, including treatments sold by vets.
Do supermarket flea treatments with fipronil really work?
Yes, flea treatments containing fipronil are highly effective at killing adult fleas and ticks when used correctly, regardless of where they are purchased.
Fipronil was previously only available through vets, but changes in regulations mean it is now also available in supermarkets and pet stores. The key factor is not where you buy it, but how the product is formulated and how it is used.
However, not all flea treatments are the same:
- Some products only kill adult fleas
- Others (such as those combined with an insect growth regulator like (S)-methoprene) also stop eggs and larvae developing
This matters because most of a flea infestation exists in your home environment, not just on your pet.
For best results, always:
- Choose a product suited to your pet’s needs
- Follow the instructions carefully
- Use as part of a complete flea control programme, including treating your home if needed
Why doesn’t fipronil always solve flea problems completely?
Fipronil kills adult fleas, but does not kill flea eggs or larvae.
This means:
- Fleas in your home can continue to develop
- Reinfestation can happen if the environment isn’t treated
For better control:
- Use a product with an insect growth regulator (IGR) like (S)-methoprene (Bob Martin CLEAR PLUS range)
- Treat your home with a flea spray or environmental product
Does fipronil have any side effects?
Fipronil is generally safe when used as directed, but like all treatments:
- Some pets may experience mild skin irritation or sensitivity
- Rarely, you may notice itching or hair loss at the application site
If you’re concerned, speak to your vet.
You should always apply the spot on to the back of your pet’s neck. This way, it’s harder for them to lick off. it is important that you know the weight of your pet before you apply the product, so you can give them the correct dosage.
Our vet says: You should never ever apply dog spot on treatments to cats, or to any animal other that what it is intended for.
How do I apply fipronil spot-on correctly?
Correct application is key for both effectiveness and safety.
Plan:
- Read the product instructions thoroughly
- Use the correct dose based on your pet’s weight
- If you need to wash your pet then do it in the days before applying the medicine, rather than afterwards
- Pick a time to apply the medicine when you won’t be in close contact with your pet, for example at night or before you go to work
Apply:
- Part your pet’s fur at the application site(s) until you can see the skin, apply directly to the skin not the fur
- Make sure your pet cannot lick the area
- Don’t touch the application site until it is fully dry
Is fipronil the most effective flea treatment?
Yes, but it’s worth bearing in mind that fipronil alone won’t kill the eggs or larvae in your home. Use Clear Plus Spot On with fipronil +s-methoprene for better protection. If you have a heavy flea infestation you’ll need to spray your house with a home flea spray also.
How does fipronil affect the environment?
Some flea treatments, including those containing fipronil, can be harmful to aquatic life if they enter rivers, lakes or waterways. This is because fipronil is designed to target insects, so it can also affect aquatic insects and ecosystems when it gets into water.
Flea treatments can enter the environment through:
- Pets swimming straight after treatment
- Washing pets or bedding
- Residue transferring from fur into drains and wastewater systems
- Fur from treated pets being used by birds to build nests
How can I reduce environmental impact when using fipronil spot-on flea treatments?
You can make a big difference by following simple steps:
- Do not let your pet swim for at least 4 days after application
- Try to limit swimming and washing of your pet in the weeks after application
- Put pet fur from treated animals in the bin, don’t leave it out for nesting birds
How should I dispose of spot-on flea treatments safely?
- Dispose of used pipettes with household waste, don’t rinse them down the sink or recycle
- Do not pour leftover product down sinks or drains
- If some of the liquid gets onto your hands, you can remove it with a paper towel, put that into your household waste bin and then wash your hands
Responsible disposal helps protect the environment while keeping your pet safe.
How often should I use fipronil to treat my pet for fleas?
For ongoing protection:
- Reapply as part of a regular monthly flea control routine
- Do not apply more frequently than instructed
Consistent use helps prevent infestations returning. Don’t forget, effective flea control also means treating your home environment. Using a flea spray or home treatment helps target eggs and larvae in carpets, bedding and furnishings, reducing the risk of reinfestation.
