Thanks for posting your query at DoctorSpring.com
I am Dr.R.K and I am pleased to assist you.
No , Fennel seeds do not interact with rifaximin.
In fact, the interaction between fennel seeds and ciprofloxacin itself is not a confirmed one.
So there is no need to worry that you have taken fennel seeds along with rifaximin and that fennel seeds would have affected the absorption of rifaximin.
I hope that answers your question.
Let me know if I can assist you further.