From Longman Dictionary of Contemporary Englishside effectˈside efˌfect ●○○ noun [countable] 1 MIan effect that a drug has on your body in addition to curing pain or illnessharmful/serious/adverse etc side effect a natural remedy with no harmful side effectsside effect of the side effects of the medication2 EFFECT/INFLUENCEan unexpected or unplanned result of a situation or event These policy changes could have beneficial side effects for the whole economy.
Examples from the Corpus
side effect• A side effect of tuna fishing was the death of over 100,000 dolphins annually.• Stomach ache is an additional side effect.• Possible side effects of the treatment include nausea and diarrhea.harmful/serious/adverse etc side effect• Orthostatic hypotension occasionally is a serious side effect.• The only instant adverse side effect is a desperate thirst, stiff aching muscles and a loss of appetite. 