ineffective(not having the desired effect; ineffectual) adjective [UK: ˌɪ.nɪ.ˈfek.tɪv] [US: ˌɪ.nə.ˈfek.tɪv]The 5% topical solution was ineffective at reducing eczema outbreaks. = La solución tópica al 5% fue ineficaz para reducir los brotes de eczema.
inefficient(not efficient; not producing the effect intended or desired) adjective [UK: ˌɪ.nɪ.ˈfɪʃnt] [US: ˌɪ.nə.ˈfɪ.ʃənt]