Drug addiction affects every organ in the body. Aside from overdose, there are many adverse medical effects of drug addiction. These include: Cardiovascular disease Contraction of HIV, hepatitis, and other illnesses Heart rate irregularities, heart attack Respiratory problems such as lung cancer, emphysema, and breathing problems Abdominal pain, vomiting, constipation, diarrhea Kidney and liver damage Seizures, stroke, brain damage changes in appetite, body temperature, and sleeping patterns Stroke Pancreatitis Gastrointestinal problems Malnutrition Insomnia and sleep disorders