I believe you reach steady state in your blood in under a week. As far as any effect since it is supposed to slow only most notice nothing. I found it calmed my twitches to almost nothing in under 2 weeks which is not uncommon and noticed a small return of last function lost at 3-4 weeks that persisted for a number of months. This is HIGHLY unusual if it was the riluzole. I think it was but it could also have been a small reversal as documented to occur by Dr Bedlack in a small percentage of PALS