Repeatedly using cocaine can cause tolerance to the drug. This tolerance can cause people to take greater amounts or to use cocaine more often to get the same high. Such use of cocaine can lead to strange, unpredictable behavior. Some people who abuse cocaine experience panic attacks or episodes of full-blown paranoid psychosis, in which they lose touch with reality and hear sounds that aren’t there.
Different ways of using cocaine can produce different bad effects. For example, regularly snorting cocaine can lead to hoarseness, loss of the sense of smell, nosebleeds, and a constant runny nose. Cocaine taken by mouth can reduce blood flow in your intestines, leading to bowel problems.