What are some of the symptoms of some one on cocaine.?

Behavior changes. Someone might be using if they show some of the following: they seem more energetic, loud, funny and excited when they are normally more reserved. They may have a runny nose, they touch their nose often and excuse themselves to go to the restroom frequently. Cocaine is a very "selfish" drug, and users need to "top up" a lot, leading to frequent "disappearances" in social settings.
Cocaine Symptoms. Some addicts use smaller amounts, less often, and may be more alert, have more energy, and milder withdrawal symptoms, headaches, mild depression, and cravings. This is similar to other stimulants including excessive caffeine use, ritalin, (methylphenidate) amphetamines, even otc medications like pseudoephedrine. It is more difficult to identify a Cocaine user/addict when they are using smaller amounts.
Acute or chronic? On cocaine, users are "full speed ahead". Some are funny, grandiose & do things fast, others get agitated & at times paranoid or delusional. In either case judgement & insight are impaired. 24 to 48 hrs after last hit, depression and suicidal thought or acts can occur. Chronic use leads to moodiness, irritability, lost work, serious money problems, loss of relationships, poor health & self care.