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Why Don’t Flea Treatments Work?

Why Don’t Flea Treatments Work?

You apply your favorite flea treatment on your pets, only to find out it’s not working. What should you do now?

Don’t worry; flea treatments not working are common, and most fur parents have experienced the dilemma.

We understand how fleas can ruin your pet’s day, especially since they can cause serious diseases detrimental to your pet’s health.


It’s probably because of an expired product, misapplication, or something else. But the most common reason why flea treatments don’t work include the following:

  • You’re using flea shampoo
  • It’s a matter of misapplication
  • You’re not applying flea treatment to all your pets
  • Your pet’s skin is dry or not in the healthiest state
  • Learn to wait, even with bathing

When all else fails, check the product’s expiration date. If it’s expired, it naturally won’t work anymore.

For all fur parents, this guide is for you. We’ll explain why your flea treatment won’t work and what you should understand about the flea cycle.

Understanding the Flea Cycle

Understanding The Flea Cycle

Fleas are some of the most common pests affecting animals, particularly pets. And for the flea treatment to work effectively, you should understand how fleas mature from eggs into adults.

Fleas have four major stages — eggs, larva, pupa, and adults. Adult fleas are the common stage that lives on your pets, but some can also invade your house.

When the adult fleas lay eggs, they hatch into caterpillar-like larvae that feed on debris, dust, and poo.

When the larva is matured enough, they form a camouflaged cocoon from dust and carpet fibers. It’s inside the cocoon where the larva transforms into an adult with long legs capable of jumping.

It’s up to the adult flea whether it will hatch a new set of eggs or stay inside the cocoon.

Remember that no flea-killing products or treatment can effectively kill the pupa inside the cocoon.

What Does This Mean?

What Does This Mean?

Flea products contain adulticide — a certain chemical that kills adult fleas. But only some contain the right ingredients to kill the eggs or the larval stage.

This means that when only the adult fleas are killed, you should also stop the infestation of the rest of the flea cycle stages. It would take you roughly five to six months!

Yes, finding a product that could kill all four stages of the flea cycle is crucial.

Next, the cocoon stage is generally resistant to all types of insecticides. This allows the pupa inside the cocoon to survive for at least three months.

So, if you want the flea product to be successful, you should constantly treat your pet with the flea product for at least three months!

Remember, you need to be religious in treating your pet. Any break in the treatment program can lead to the hatching and feeding of the pupa, which eventually leads to the egg-laying stage again.

This destroys everything, so you must go back to square one.

Reasons Why Your Flea Treatment Won’t Work

Reasons Why Your Flea Treatment Won't Work

Now that you understand the importance of the flea cycle in treating your pets let’s look at why your flea products won’t work.

1. You’re Using Flea Shampoo

You're Using Flea Shampoo

We’ve talked with several fur parents, who often apply spot-on flea treatment instead of using flea shampoo. That’s wrong!

Here’s the main reason why. Most spot-on flea products need your pets’ natural oils on their fur to spread on them effectively, but if you have just bathed your pet and applied flea shampoo, their natural oils have already been stripped off. The result? The spot-on treatment becomes less effective.

The most probable solution is always to check the spot-on product recommendations.

Generally, they will advise you to only use the treatment at least two days after bathing. Or you cannot bathe them two days after applying the spot-on product.

2. It’s a Matter of Misapplication

It's A Matter Of Misapplication

Applying flea treatment should become a habit. But it won’t be effective if you apply it incorrectly.

Moreover, we know how flea prevention can be expensive, so it’s always essential that you don’t waste even a single dose.

If you’re using topical medication, remember to apply it directly to the pet’s skin and not on his fur. You should part the pet’s hair to reach the skin and apply the product.

Additionally, it helps to read the product’s packaging, where you will often find directions about the proper application.

Most products will instruct you to apply the treatment in only a single spot on the animal’s neck. But some will also advise you to apply for several spots, especially in areas unreachable by your pet.

3. You’re Not Applying the Treatment to All Your Pets

You're Not Applying The Treatment To All Your Pets

If you’re a fur parent of various animals, understand this: flea treatment will only work if you apply it to all your pets.

It’s useless to treat your dogs if there are adult fleas that could invade your house and affect other pets.

Forgetting to treat your dog, even just for a day, can make them susceptible to catching fleas again.

That’s why you must treat all your pets at home with a good-quality flea product.

4. Is Your Pet’s Skin Dry or Not in the Healthiest State

Is Your Pet's Skin Dry Or Not In The Healthiest State

Because the flea treatment is applied to your pet’s skin, it’s also essential that it’s healthy and not dry.

Dry skin means your pet lacks enough sebaceous glands, which are important aspects where the flea treatment will be absorbed.

When the product does not reach these glands, the flea treatment will not be effective and successful.

If you think your pet’s fur is too thick, visiting the grooming salon should do the trick. Grooming can also allow your pet’s skin to exfoliate, which is important so that the dead skin cells will be shed.

Always remember that flea treatment is more effective without dry and oil-less dead cells.

5. Learn To Wait

Learn To Wait

Don’t expect spot-on flea treatments to work seconds after the application.

After applying, wait at least 12 hours before the product will start repelling and killing fleas and even ticks on your pet’s skin. As more time passes, infestations in your house can also be treated.

Applying anti-flea products also means you should not take your pet to the grooming salon within 2 days to give the product enough time to work.

Even when your pets are wearing a flea collar, you should wait 48 hours before bathing them. The flea collars may be waterproof, but they still need the 2 days window period to work.

Protect Your Pets From Fleas

Protect Your Pets From Fleas

By now, you should know that the common reasons why flea treatment won’t work are simple and practical.

Your pets should stay protected from them, so you must diligently follow product recommendations.

Moreover, it’s all about understanding how the treatments work about the fleas’ life cycle. When you completely understand this, everything else should fall into place.

Frequently Asked Questions

What’s a Possible Reason Some Fleas Are Still Alive After the Treatment?

If you still see fleas at home even after treating your pets with the right product, don’t panic.

It’s more likely that the treatment worked on your pet, but some adult fleas could hatch new eggs before they died. Hence, you see a new round of fleas invading your property.

What Can Kill All the Stages in a Flea Cycle?

The best product that can kill all stages in the flea cycle contains adulticide and an insect growth regulator.

Adulticide kills adult fleas, while the regulator kills the other stages — from the eggs to the larva and the pupa.

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