Medical deficiency
Theoretically, according to 14 CFR 61.53, taking ANY medication means that you have a medical condition that would render you unable meet the requirements of your medical:
Sec. 61.53 - Prohibition on operations during medical deficiency.
(a) Operations that require a medical certificate. Except as provided for in paragraph (b) of this section, a person who holds a current medical certificate issued under part 67 of this chapter shall not act as pilot in command, or in any other capacity as a required pilot flight crewmember, while that person:
(1) Knows or has reason to know of any medical condition that would make the person unable to meet the requirements for the medical certificate necessary for the pilot operation; or
(2)
Is taking medication or receiving other treatment for a medical condition that results in the person being unable to meet the requirements for the medical certificate necessary for the pilot operation.
(Emphasis added)
Obviously, you need to use some judgment. Every medication has some sort of side effect, but it is not unreasonable to take Tylenol for a headache and fly after the headache passes. The FAA can approve prescription medications on a case-by-case basis for those who need them. So many of the motion sickness meds, though, have antihistimines, which induce drowsiness.
Best thing is stay away from them. Don't worry, your airsickness tendencies will pass soon.
An interesting pilot medical site is
www.leftseat.com .
Good luck with your lessons.