Side Effects of Dog Flea Medication

Fleas usually start out as a nuisance for your dog, but if left untreated, can cause your dog to become very sick. Flea control is important for any household that has dogs; canine flea control medication is available at pet stores, online and at your veterinarian's office. However, before you buy any flea control medication, it is important to understand the possible side effects associated with the product you choose.

  1. Skin Irritation

    • Adverse skin reactions can arise with the use of topical dog flea medication. These skin irritations include pruritus, which is severe itching of the skin. Along with the itching, the skin can crack and bleed, causing open sores, which can then lead to infection. Erythema, or intense redness of the skin, blisters, and hair loss can also occur. These skin irritations can arise all at once, or you may notice only one or two of these side effects.

    Pyrethrin/Permethrin Toxicity

    • Permethrin is a synthetic insecticide found in some dog flea spot treatment products; the plant-based version of this compound is pyrethrin. Both chemicals are toxic, which is why they work to kill fleas. However, they can also be toxic to your dog, especially permethrin. Using a dog flea control medication that has permethrin can cause dog behavioral changes, depression, weakness, scratching and vomiting.

    Weakened Immune System

    • Some dog flea medications and even dog flea shampoos contain toxins, including neurotoxins, all with the intended purpose to kill fleas. However, fleas can build up more resistance against these ingredients with every new generation hatched. Your dog cannot. Continual use of these products will cause an accumulation of toxins in your dog's body, which in turn can weaken its immune system.