Crack cocaine is an addictive stimulant drug that affects the central nervous system when inhaled and produces a number of behavioral symptoms when the user is currently high. Once inhaled, the crack tends to affect the user for five to 15 minutes and creates the urge to smoke again to regain the dopamine rush produced during the initial inhalation.
Look at the user's eyes. A user under the influence has dilated pupils, a physiological effect of the drug.
Observe the other person's body language. Nervousness in the form of jerky body movements or shaking hands is common during the user's period of being high.
Watch for aggressive or paranoid behavior. The drug's effect on the central nervous system causes intense mood fluctuations, which often include a hostile tone or rapid speech while under the influence of crack.
Check for rapid breathing. The increased breathing is connected to feelings of anxiousness and can cause the user to appear frenzied or paranoid.
Observe the user's behavior for a drop in mood. Some users appear anxious when high, while others may display symptoms of depression. A person who suffers from depressive symptoms while high may complain of pain or seem disoriented due to the feeling of dizziness.