Side Effects is the 12th episode of Ben 10. It marks the appearance of Clancy, the bug maniac.


A man named Clancy, who has the power to control insects take revenge on Councilwoman Liang because she wants to tear down the building where he and his insects live. Meanwhile Ben has to deal with the strange side effects a cold has on his alien forms.


  • Ben
  • Gwen
  • Max
  • Clancy
  • Councilwomen Liang
  • Upgrade
  • Wildmutt
  • Heatblast (sometimes called Coldblast)
  • Fourarms (sometimes called Itchyarms)



Previous episode: A Small Problem

Next episode: Secrets

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