reactogenic

re·ac·to·gen·ic (.)rē-.ak-tə-'jen-ik adj capable of causing a reaction and esp. an immunological reaction <a highly \reactogenic vaccine>

re·ac·to·ge·nic·i·ty -jə-'nis-ə-tē n, pl -ties

* * *

re·ac·to·gen·ic (re-ak″to-jenґik) [reaction + -genic] causing an excessive local or systemic reaction; said of vaccine.