c. 1200, "to become ill," from sick (adj.) + -en (1). Transitive sense of "to make sick" is recorded from 1610s. Related: Sickened; sickening. The earlier verb was simply sick (Old English seocan) "to be ill, fall ill."
The pornographic pictures sickened us
The mold on the food sickened the diners
This kind of food sickens me