A sign is something other people, like a doctor, notice while a symptom is something that the patient describes. For instance, drowsiness might be a symptom while dilated pupils might be a sign.
Dependence on a substance - the person who is addicted to a substance like alcohol or drugs loses the ability to decide when to use and when not to use such. Although the user may not know that there is a potential to get hurt, they will keep taking it, even though it can cause harm.
Substance reliance can bring about effective yearnings. Addicts may desire to quit (give up), however experiences it very hard to do without assistance.
The clues and indicators that someone is addicted differ from one person to the other, depend on the drug, the genes of the individual and status in life.
The clues and indicators of addiction could be that:
Some people who abuse drugs or alcohol might not be technically addicted but can still suffer the effects mentioned here but do not usually suffer from withdrawal symptoms or have the same obsession to use the substance.