text: Usually these durgs kick in, generally speaking, within 4-6 weeks or even earlier. Alternative drug should be considered if desired effect hasnt been obtained from  Luvox (Fluvoxamine) after 12 weeks of starting therapy, and it is 4-6 weeks in case of Lithium. Effectiveness of drugs also depend on the dose. It is unlikely for a drug to show any effect if the dose is suboptimal. However, u should consult the prescriber for dose adjustment or other options if you think u have been taking them for long enough. Hope it helps.