Frontline Top Spot Side Effects

Frontline Top Spot is a flea and tick pesticide containing the active ingredient fipronil, created by drug manufacturer Merial. Frontline products are generally considered safe for healthy pets, but it can have side effects, especially in the very young, sick, or elderly pets. Pet owners who choose Frontline products should be aware of the possible side effects that can occur with the use of fipronil as a topical pesticide.

  1. Use

    • Fipronil is the active ingredient in all Frontline products, including Frontline Top Spot. It is a pesticide used topically for flea and tick control, effectively killing fleas and ticks on dogs and cats within 18 to 48 hours after the initial application. Fipronil is also used as an ingredient in other pesticides, such as ant bait, roach bait and to kill termites.

    Side Effects

    • While most animals do not have an adverse reaction to Frontline Top Spot, fipronil does have known side effects. The most common side effects are drowsiness and irritation, itching, or hair loss in the area where the Frontline Top Spot was applied. Other more serious side effects include vomiting, increased salivation or excessive drooling, changes in the heart rate, decreased appetite, diarrhea, site irritation, lethargy, muscle tremors, decreased coordination and convulsions.

    Considerations

    • While serious side effects are not considered common, they do occur in a small percentage of animals. The risks are higher in sick or elderly animals, and the risk of side effects is also higher in pets under the age of 8 weeks. The makers of fipronil also caution against using their products on pregnant or lactating animals, or if you plan to breed your animal within 30 days of treatment with any Frontline products.

    Expert Insight

    • According to the Journal of Pesticide Reform, Spring 2005, Vol. 25, Vol. 1, laboratory tests proved conclusively that the active ingredient in Frontline flea and tick pesticides caused an increase in aggression, damaged the kidneys and caused changes in the function of the thyroid gland.

    Misconceptions

    • Fipronil has been proven to be systemically absorbed, and according to Virginia Dobozy, a veterinarian at the United States Environmental Protection Agency, fipronil products are classified as carcinogens, as studies showed that laboratory animals treated with pesticides containing the active ingredient fipronil have produced malignant (as well as benign) tumors in laboratory tests.