I'm thinking you meant "topical flea meds?" If so, follow the directions given to you on your flea meds package. It often states that after applying flea medication, to WAIT three days before using any shampoo.
The "Itch Stop Shampoo" does contain hydrocortisone -- therefore, I cannot say for sure if more attention to details is needed. I, myself, have used it on my dogs -- at least three days or longer AFTER flea medications applied. It did not produce any negative reactions. Also, I do not believe Itch Stop Shampoo would "remove" flea medication from your animal's coat since flea medications are usually fully-absorbed after three days of application.
Definitely check the instructions on your topical flea medication phamplet. If still in doubt, don't hesitate to contact Drs. F&S: 1-800-562-7169. They are always willing to assist. Have the name of your topical flea medication available when you ask about utilizing "Itch Stop Shampoo" after flea med application.