no good answer due to normal variations in physiology and variations in the specific person’s quality and severity of addiction but in terms of timescale I would say a day-ish? Would be better to ask an ICU RN or MD. At my level and specialty of care (acute psychiatry) and assuming the pt has been screened appropriately by the ED to not already be in high acuity withdrawal (needs medical or ICU) we’re generally not talking a minutes to a couple hours but we’re also not talking a week. The scale we use to measure is called the Clinical Institute Withdrawal Assessment. Depending on the half-life of the medication used for the taper I’m reassessing that score either every 4 hours (ativan) or every 8 (phenobarb). My unit usually does phenobarb because it requires less frequent and precise assessment due to the elongated half-life. And I can always reassess ahead of schedule and give 1 extra dose as a standing PRN order without even needing to call the on-call MD if they’re having breakthrough symptoms.