Dog/Cat Flea Treatment Side Effects

Fleas may often affect cats or dogs and can be removed employing several treatments. However, some pets may have negative reactions to these treatments; find out about the dog cat flea treatment possible side effects.


Dermatitis or the occurrence of rashes may be due to several anti flea treatments such as flea powders, sprays or shampoos. The dog may be allergic to the insecticides that are included in these products to kill the fleas. The side effects may vary in intensity; some pets may display mild skin reactions, while others will get swollen and highly irritated.

Should you notice rashes on your dog’s skin, you need to visit the vet to find an alternative treatment.

In some cases, the vet will not recommend the discontinuation of the flea treatment until the fleas are gone. The dermatitis is a minimal side effect compared to the problems fleas create. The vet may recommend a few steroid topical ointments.

After the fleas are gone and the treatment is discontinued, the dermatitis will be gone too.


The flea treatments that are applied topically may cause irritation and itchiness of the skin.

You may notice that the dog continues to scratch his skin even after the fleas are gone. You should consult the vet to see if you can find some ointments that could stop the itchiness.

Once you discontinue the administration of the anti flea treatment that causes itchiness, the dog will no longer scratch.

Dry Skin

Certain flea powders or shampoos may cause dry skin in your pet. The dryness may be due to the compounds of the products which can disrupt the normal pH of the skin.

The vet may recommend a few creams for topical use or he may recommend a few anti flea products that contain natural ingredients and fewer artificial additives.

Vomiting and Diarrhea

Vomiting and diarrhea may be side effects caused by oral anti flea treatments. The pet’s stomach may not respond well to the medication and eliminate it.

In this case, the medication may not have the flea killer effect, so the medication should be administrated again or you should opt for alternative treatments.

Other less common side effects that flea treatments may have in cats or dogs include brain damage, heart attacks, seizures or lethargy.

Avoid Side Effects

To avoid the possible flea treatment side effects you should always avoid over the counter anti flea products. These may not be tested and may cause negative reactions in your pet.

You should also make sure that the products you purchase don’t contain organophosphate insecticides or OPs, pyrethroids, chlorpyrifos, dichlorvos, phosmet or diazinon. These compounds have been linked to side effects such as brain damage, heart attack or seizures.

Always check the labels for side effects and possible interactions with other drugs, if your pet is under other medication.

Check with your vet prior to getting a product if your pet is senior or has severe allergic reactions (anaphylaxis) to different compounds.