undesirable
adj.adj. not wanted or liked because it is unpleasant or harmful. You use this to describe things that you would rather avoid.
adj. not wanted or desirable because it is harmful, objectionable, or unpleasant. Often used to describe side effects, social outcomes, or physical qualities.
The medicine has some undesirable side effects.
The new factory might bring jobs, but the increased traffic is an undesirable consequence for the local residents.
While the policy was designed to stimulate growth, it inadvertently created several undesirable market conditions that the central bank struggled to correct over the following fiscal year.
From un- + desirable.
Typically used attributively before a noun, though it can follow linking verbs like 'be' or 'become'.