What is the side effects of using cocain?

Several. Cocaine is a CNS stimulant, as a result is very addicting. Chronic nasal/oral inhalation can damage lungs, teeth, gums, nasal septum. Can also cause more serious conditios like stroke, mi resulting in heart failure. Overdose can cause death. Last but not the least serious psychosocial damage. These are only few of the many adverse effects.
Heart attack, stroke. And sudden death for starters. If Cocaine is snorted, it can damage the nasal septum, ultimately causing a perforation in the wall between the nostrils and collapse of the bridge of the nose, as well as respiratory and sinus infections. It can cause heart rhythm disturbances, psychotic behavior and paranoia, increase aggression suicide and violence. Iv use=serious infection, smoking = lung damage.