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5 Signs Your Flea Medication Isn’t Working and Tips From Your Local Vet

In News by Pharr Rd. Animal Hospital2 Comments

Fleas are such a menace, aren’t they? They certainly drive us nuts, and our furry friends, of course. Which is why we highly recommend the utilization of flea medication.

What, though, if you have a sneaking suspicion the flea medication you applied to your furry friend isn’t working?

You need to confirm your suspicions! That’s why we are sharing with you our top five signs that a flea medication isn’t working.

5 Signs Your Pet’s Flea Medication Isn’t Working (or Never Was!)

When suspicions arise regarding flea medication, we recommend looking for these – the most common signs a flea medication is no longer (or never was) working for an animal.

1. You See Fleas

Yes, we agree – this one is highly obvious. But we wouldn’t be a proper veterinarian office if we didn’t point out the obvious options first.

So, if pet owners see evidence of fleas – either fleas in their home or on their pet – we find it’s safe to assume the flea meds aren’t working.

We should also point out evidence of fleas doesn’t necessarily mean the flea medication was never working to begin with.

When we see fleas on an animal, what we don’t see is the thousands of eggs they have laid. It takes weeks before the new fleas are ready to hatch. Therefore, the fleas a pet owner may be seeing today are most likely not the original fleas (which have probably since been killed by the flea medication), but rather their flea offspring.

Eventually, all of the fleas should be gone. If fleas keep presenting themselves, however, this is a definite sign the medication isn’t working.

2. Your Pet is Itching, Scratching, or Biting Themselves

This is another obvious sign a pet has fleas. Our poor pets – flea bites are no fun. Some animals are so desperate to stop the itching they not only scratch at the bites, they actually bite themselves to relive the itch.

It’s important to note, though, itching isn’t always a sign of fleas. In actuality, it may be an allergic reaction a pet is having to the medication. In these cases, it’s important to get the pet to a local vet to ensure no further reactions will occur and to give your animal some relief.

3. Your Pet’s Skin is Red and Inflamed

In most cases, if a pet’s skin is red and inflamed, the likely cause is an allergic reaction – either to some kind of bite (including that of a flea) or the flea medication. Taking the pet to a veterinarian will help pet owners get a diagnosis and some treatment so their pet doesn’t have to suffer any longer.

4. Your Dog or Cat is Starting to Lose Hair

Hair loss is another sign the animal is either still experiencing an attack from fleas or they’re having an adverse reaction to their flea medication.

However, hair loss can also be a sign of other minor to moderate health conditions in animals and should be addressed by a veterinarian as soon as possible. The faster this happens, the more quickly your local vet can come up with the proper diagnosis and treatment plan.

5. Your Animal Becomes Lethargic

Vomiting and lethargy could be signs of toxicity in a pet. Some pets, particularly dogs, tend to lick just about anything – including their flea medication. Ingesting topical medications can definitely make pets feel sick.

Even oral flea meds can make a pet sick if they’re delivered in a protein pack the animal is sensitive or allergic to. These packs are used to entice the pet to eat their “tasty treat” but if the pet can’t eat certain proteins, the result could be vomiting and lethargy.

And when a pet removes their medication (via licking) or vomits their oral meds, it’s not difficult to see why the medication might not seem very effective.

What to Do If Your Flea Meds Aren’t Working

To ensure a pet is getting proper anti-flea care, we recommend bringing them to your local vet office to evaluate and help determine which medications would be best.

Is your animal suffering from constant flea bites? If so, contact Pharr Road Animal Hospital right away. We’ll provide your pet with relief and help prevent future flea attacks.


  1. After treatment with frontline plus a week ago my long haired Chihuahua still has fleas what do I do ?

  2. I’ve used a treatment of tablets and spot on treatment and she’s been sick does that mean treatment won’t work?

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