Thanks for the question. Alcohol is a neurotoxin. This fact helps us understand a couple of its effects on the body. Firstly, alcohol itself can damage nerves, which can result in numbness, tingling, and even twitching like you describe. But more likely here is that your son is going through alcohol withdrawal. For heavy drinkers, drinking less than normal, even if you don t stop drinking entirely, can result in withdrawal, one of the most common signs of which is tremor (shaking). I recommend your son seek treatment from a primary care physician, psychiatrist, or if he is in alcohol withdrawal go to the nearest ER to detox and seek help from a rehabilitation facility. Withdrawal can result in death and is a serious matter. I hope this is helpful to you. Dr. Sheppe