Table of Contents
The flea life cycle
Picture of flea life cycle
How to use flea treatment correctly
Patience is key
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Why are fleas still alive after treatment?
- By Sarah
-
- September 12, 2025
- 3 MIN READ
Fleas are a constant threat, all year round and require more than just one application of treatment to be eradicated. To get rid of fleas you must establish a flea control routine. If you’re still seeing fleas after treatment it could be because of a few different reasons - But you can solve everyone yourself! Keep reading to get on top of your flea infestation.
The flea life cycle
Let’s start with the flea life cycle. Fleas are not just the tiny brown adults you see jumping on your pet. They go through four different stages and each one is a threat:
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Eggs
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Larvae
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Pupae
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Adult
Picture of flea life cycle
Most treatments are designed to target adults, but you need to kill fleas at every life stage - eggs, pupae and larvae, as well as the adults. That’s why it’s important to use flea treatment, like the Itch Flea Treatment for Dogs and the Itch Flea Treatment for Cats. With a double-action, vet strength formula, Itch Flea kills adult fleas on your pet but also targets flea eggs and larvae to stop them causing a full blown infestation.
How to use flea treatment correctly
Timing is everything
After applying flea treatment, you may expect immediate results. However, some products take 24 - 48 hours to kill adult fleas. So if you see fleas up to 2 days after treatment, don’t panic. They will be zapped dead very soon.
It’s also worth noting that flea pupae (the cocoon stage) are particularly resilient. They can remain dormant for months before hatching, especially if conditions aren’t ideal. A sudden burst of warmth or vibration — like your dog walking through the room — can trigger them to emerge. Click here to find out about dormant fleas.
Treatment resistance
Over the years, there’s been concern about flea resistance to certain active ingredients. Just as bacteria can become resistant to antibiotics, flea populations can adapt to survive certain chemicals. This is why some older products may not be as effective as they once were.
Application errors
Sometimes the issue isn’t the product itself, but how it’s used. Common mistakes include:
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Not applying the full dose based on your pet’s weight.
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Bathing or getting your pet wet too soon after application.
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Splitting doses between two animals.
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Applying the product in the wrong area (spot-on treatments need to be placed directly on the skin, at the back of the neck, not the fur).
Environmental factors
95% of fleas live in your environment, not on your pet. Fleas can nestle and breed in your:
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Carpets - Click here to find out how to spot fleas in your carpet!
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Pet’s bedding - Click here to find out whether fleas can live on bedding
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Sofas and cushions - So can fleas really live on furniture? Find out here!
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Car interior
Even if your pet is treated, fleas from the environment can jump straight back on. To break the cycle, you’ll need to:
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Wash pet bedding at 60°C.
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Vacuum thoroughly, especially in corners and under furniture.
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Use a household flea spray, like the Itch Flea Home Spray that kills fleas and stops the development of flea eggs and larvae for up to 12 months.
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Treat all pets in the household at the same time.
Patience is key
It can take several weeks of consistent treatment and cleaning before a flea infestation is fully controlled. Spot-on treatments, like Itch Flea Treatment for Dogs and the Itch Flea Treatment for Cats usually need to be repeated monthly. The Itch subscription service makes this easy. Tailored treatment for your pet, delivered for free, every month, exactly when you need it.
Think of it like tackling weeds in a garden — a single round of treatment won’t get rid of the problem entirely. Persistence is crucial.
If fleas seem to survive after treatment, it doesn’t always mean the product has failed, it usually means small mistakes in application or that you need to use something stronger. Flea treatment that kills both fleas and their eggs, will stop infestation. Click here to find out about active ingredients that target fleas and flea eggs.
Remember that fleas live in your home, as well as your pet. Treat both for ultimate protection.
Protect your home from fleas.
95% of fleas live in your home environment, not on your pet.
To break the fast and furious flea life cycle, treat your home with Itch Flea House Spray. In one blast, it will help turf out the little blighters — and any dust mites too — as well as put a halt to the development of flea eggs and larvae for up to 12 months.
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Flea
Treatment Issues
Why is my pet still scratching after applying a flea treatment?
Not all flea treatments are created equal. So it may be the treatment you used hasn’t done the job and you need to use something stronger. Itch Flea Treatment is a vet-strength, double action spot on treatment that not only contains Fipronil but also (unlike lots of other flea treatments), (S) Methoprene. Treatments that also include (S) Methoprene, like Itch Flea Treatment not only target the adult fleas feeding on your pets and kills them dead in 24 hours (and ticks in 48 hours), but also targets flea eggs and larvae, stopping the fast and furious flea life cycle dead in its tracks to stop new fleas developing.
We asked in-house Itch vet, Dr. Zoe Costigan to give us the lowdown on why your cat or dog might still be scratching after applying a flea treatment to your pet. Here's what she had to say:
“It’s fairly normal for there to be a period of hyperactivity amongst the fleas as the active ingredients in a flea treatment take effect and this can cause an increase in your pet scratching. It should settle down after 24 hours. If after 24 hours your pet continues to scratch, there could be other things going on. Your pet could be flea-allergic, it could have a skin infection or a hormone imbalance, or other conditions which can lead to itchiness.”
Flea
Identification
Why do I suddenly have fleas in my house?
Fleas can come into your home at any point and stay there for as long as 6 months. Keep reading to find out what has probably brought fleas into your home and how to get rid of them.
Itch Insights
Pet Wellbeing
How to spot a fake flea treatment!
The government warns pet owners to beware of fake flea treatments that contain toxic chemicals. Counterfeit flea treatments are being sold by third-party sellers online to UK pet parents and are poisoning cats and dogs.
Fake flea treatments are not regulated by the Veterinary Medicines Doctorate (VMD), which means they are not scientifically licensed, proven or approved. And they may contain toxic chemicals, dangerous to your pet. Keep reading to find out the red flags for a fake flea treatment, and what to use instead.