text: how long to take effect? hlong does it take to notice if the meds i am taking are working or not (lithium&luvox) 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.