Herbal flea and tick products like Arks Flea Flicker! Tick Kicker! tend to be safer than pharmaceutical flea/tick products. That being said, all products that are formulated to rid pets of fleas and ticks pose a % of risk.
The ingredients in Flea Flicker! Tick Kicker! are labeled as GRAS (Generally Regarded As Safe) ingredients by the EPA and FDA. Generally means generally. It doesnt mean its a 100% safe solution for every dog and cat. It means the incidence of problems with the ingredients in Arks product fall into a low range.
Typically herbal products used correctly pose less of a risk with dogs than cats. Remember to follow the instructions on the bottle, do not saturate the pet, and do not spray on face or genitals.