How long do the effects of Ketamine last after ingesting?

If you are talking about withdrawal symptoms from a narcotic drug (oxycontin, MS contin, oxynorm, endone, etc) then symptoms will last 4 or 5 days. They will include shivers, sweats, headaches, diarrhoea, shakes, jitters and generally just not being able to function. I was on high doses of oxynorm (an immediate acting narcotic tablet for debilitating osteoarthritis) and I have had two episodes of withdrawals...it occurs if I take high doseages, and then go off them suddenly. You do feel awful, but it will get better. Now I tend to take my pain relief every couple of days, if I can, with sometimes a four day period of no pain relief. I don't take them regularly anymore, and this tends to reduce the withdrawal symptoms.