、。
When drugs are abused, they can damage people's health.
Literal
Medicine [subj-が] be-abused-[passive-される]-[cond-と], people [gen-の] health [obj-を] harm-do possibility [subj-が] exist.
The conditional ~と here expresses a general/automatic consequence — 'whenever X happens, Y follows.' Distinct from ~たら and ~ば in that it's used for natural laws, habitual sequences, and inevitable outcomes. 健康を害する ('harm health') is a set collocation using the Sino-Japanese verb 害する. ~可能性がある ('there is a possibility that') is a common hedge for potential consequences.