side effect

English Thesaurus

1. any adverse and unwanted secondary effect (noun.phenomenon)

hypernym	:	consequence, effect, event, issue, outcome, result, upshot,
definition	:	a phenomenon that follows and is caused by some previous phenomenon (noun.phenomenon)

2. a secondary and usually adverse effect of a drug or therapy (noun.state)

hypernym	:	effect,
definition	:	a symptom caused by an illness or a drug (noun.state)

hyponym	:	black tongue, furry tongue, hairy tongue,
definition	:	a benign side effect of some antibiotics; dark overgrowth of the papillae of the tongue (noun.state)