Instructions
Talk to a veterinarian before purchasing any new flea treatment. If your pet has allergies or is on medication, a veterinarian will tell you if the new product will harm your pet in any way.
Read the product label on the failed flea medicine. Look at the dosing instructions. Do not apply a new flea product until the current dose has expired. For example, if you are supposed to apply the old flea medicine every four weeks, do not apply a new flea medicine until four weeks have passed since you last applied the old medicine.
Look to see the weight requirements for each flea prevent product. Most flea treatments come with different weight requirements. For example, one flea treatment may only work on dogs 50 to 80 pounds. Applying that product to a dog that weighs 100 pounds will render that medicine ineffective.
Apply dog flea treatment on dogs and cat flea treatment on cats. Mixing the two may result in side effects and the medicine will not work.
Use only the directed dose. Most flea treatments come in a small one-dose bottle. Applying more than directed may result in side effects and is no more effective.
How to Use Another Flea Product After One Has Failed
If you've had fleas running rampant in your house, you've probably thought that they are one of the most annoying tiny creatures in existence. Preventing fleas from latching onto your pets and making their way into your house requires flea prevention medication. However, if your previous flea medication did not work on your pet, you may need to use a different one. Exercising caution and reading the directions of both the old and new flea medication is important for your pet.