Energy drink produces aversive effects in planarians.

Energy drinks pose consumer and environmental risks. One of the few organisms suitable for investigating both risks are planarians, which display mammalian-like behavioral effects during drug exposure and reside in aquatic environments. We investigated effects of Monster Energy® (0.001 - 10%) on planarian behaviors using established assays. For acute exposure, only higher concentrations reduced motility (>1%) and caused stereotypies (>1%). Lower concentrations (0.1-1%) enhanced light avoidance, a measure of defensive responding. In place conditioning experiments conducted with low concentrations (0.0001%-0.1%), planarians avoided the energy drink-paired side. These results suggest that Monster Energy® causes aversive effects in aquatic life such as planarians.