In some users, this stress may trigger chest pain or heart attack, even on the first try. Crack can cause brain seizures, a disturbance of the brain's electrical signals, some of which regulate the heart and muscles controlling breathing. Some users have suffered strokes after using crack - the increase in blood pressure that the drug causes may rupture blood vessels. Repeated use of crack without experiencing problems does not guarantee freedom from seizures in the future. Violent, erratic or paranoid behavior can accompany the use of crack.
Hallucinations are also common.
Other psychological effects may include profound personality changes. Crack is particularly alarming because it causes an intense stimulation of the reward center of the brain by allowing the brain chemical dopamine to remain active longer than normal. This causes changes in brain activity and triggers an intense craving for more of the drug, thus creating a powerful psychological dependence on the drug. The most commonly used narcotics are Heroin, Morphine, Dilaudid, Opium, Codeine, Percodan, Methadone, and Demerol. Heroin accounts for a majority of the illicit opiate abuse in America.