inefficacious

adjectives

lacking the power to produce a desired effect
"laws that are inefficacious in stopping crime"
inefficacious
is derived from
inefficaciousness
antonym
efficacious
see also
not producing an intended effect
"an ineffective teacher"; "ineffective legislation"
ineffective, ineffectual, uneffective
is an attribute of
capacity or power to produce a desired effect
"concern about the safety and efficacy of the vaccine"
efficaciousness, efficacy