Addiction is a combination of three things: the plain drug effects, genetic predisposition, and behavioral reward/compulsion effects. Some people get the opposite effect of narcotics (which should cause sleepiness narco- Greek for sleep but in 5% cause lots of energy) some people have no controls on action (bipolar)--genetics. Then there is the drug effect of withdrawal. It peaks between 2 and 5 days after stopping and then dwindles. Some effects like heart racing might come back at any time due to panic attack and not the drug withdrawal. Other effects like aches/hot flashes/sniffles occur commonly for other common causes like colds and people (wrongly) attribute it to withdrawal forever. Clonidine is dangerous and needs supervision but it lowers stress hormones involved in shakes/sweats/heart racing. It is a blood pressure medicine and will lower blood pressure. Most people in addiction are not old enough to have high blood pressure. This is a problem. There are other drugs. Some (zofran, pepto-bismal, aspirin, loperimide) are commonly used while others (reserpine) work, but nobody uses them. None of these work on the psychological craving for drug. Long term tapering with suboxone (months to years) or methadone is somewhat helpful. 12 step programs are helpful. Behavioral work on particular parts off the cravings is helpful but nobody does it. So, integrated approach. Clonidine is a small help. It needs watching.