Drug use can damage the liver, lungs, brain, throat and stomach. Drug use also causes addiction, which can results in withdrawal symptoms when the drugs are not available, claims ReachOut.
Drug abuse can weaken the immune system and causes heart problems. Drug use also affects the brain, causing memory, decision-making and focus problems. Behavioral problems, such as paranoia, hallucinations, impaired judgment and aggressiveness, are common in drug users, according to the Gateway Foundation.
Over 75 percent of domestic violence victims reported that their abusers were on drugs or alcohol when the incidents occurred. The risk of suicide can increase above average when drug abuse is left untreated, claims the Gateway Foundation.