Although natural remedies may offer some protection or repellency against parasites, they are not nearly as effective as prescription products. In addition, natural remedies often need to be applied far more frequently than once a month, making them less convenient as well. Some, such as garlic, may actually be harmful to your pet.
Just because a product has “natural” on its label doesn’t mean it’s safe. Consult with your veterinarian before using any over-the-counter preventives on your pet.