adverse
adjective [ before noun ]
uk/ˈædvɜːs/ usharmful or likely to cause problems:
A chain reaction of adverse events in the financial markets has put lenders under severe pressure.
adverse effect/impact/change Recent bad publicity has had an adverse effect on sales.
adverse conditions/consequences/circumstances Many experts believe it may be too late to prevent adverse consequences to the world's climate system.
adverse reaction/side-effect Some people have adverse reactions to additives and preservatives used in many foods.