Alcohol detox is necessary when an individual has developed physical dependence on alcohol, which means their body has become accustomed to functioning with alcohol in their system. If they suddenly stop drinking or significantly reduce their alcohol intake, they may experience withdrawal symptoms such as tremors, seizures, hallucinations, and delirium tremens. These symptoms can be severe and even life-threatening in some cases, which is why medical supervision during alcohol detox is strongly recommended. In general, it is always best to seek professional advice and guidance when considering alcohol detox.