Addiction is a mental disease. People who often consume alcohol, tobacco, medication and illegal drugs, may become physically or mentally addicted.
Without the substance (“drug”), they experience physical and mental discomfort (for example headache, anxiety or panic symptoms = withdrawal effects).
Behaviour can be addictive as well, and can become uncontrollable.
Gambling addiction, internet addiction or compulsive buying are serious mental illnesses.
For addicts and relatives there are anonymous and free counselling centres.