Drug abuse leads to symptoms of drug dependence and addiction. According to the Diagnostic and Statistical Manual of Mental Disorders, drug or substance abuse tends to be recurrent and may cause severe damage and harm to the body in the short or long term. While some of the damage is physical, there may also be a social element, with the individual failing to fulfil their responsibilities in life and having difficulty with family relationships. Drug abuse also leads to risky and dangerous behaviors.

Some of the symptoms and consequences of drug abuse include:

• Failure to fulfil ones responsibilities (e.g., as a parent, spouse or student)
• Taking risks such as driving under the influence of drugs or alcohol
• Encounters with the law and criminal activities both as a result of drug side effects and as a means of securing funds to feed the addiction
• Domestic abuse and recurrent fights
• Absence from work or school
• Inability to overcome cravings despite awareness of the harm caused by the drug
• Withdrawal syndrome when the drug is stopped abruptly. This gives rise to unpleasant physical symptoms that result in intense cravings for the substance after an addict tries to stop using it. This is a typical feature of drug dependence and addiction after heavy, prolonged use. Most people with these symptoms often return to using the substance to ease the discomfort associated with withdrawal and to satisfy cravings. Withdrawal symptoms may be wide ranging. For example, alcohol withdrawal may cause nausea, vomiting, dry mouth, weakness, depression, headaches, anxiety, sleeplessness, high blood pressure and hallucinations. Opioids and stimulants are substances that may also lead to withdrawal syndrome if their use is stopped.
• Development of tolerance or the need for a higher dose of the drug than before to achieve the same degree of pleasurable sensation
• Tell-tale injection marks among needle users. People who snort or inhale the drug may have a damaged mucosal lining in the nose
• Lack of hygiene may be evident in addicts whose preoccupation with a drug has led to neglect of hygiene
• Features of severe malnutrition and vitamin deficiency
• Skin infections
• Transmission of blood-borne viral infections such as HIV, Hepatitis B and C as well as sexually transmitted infections due to risky sexual behavior while under the influence of a substance