How do I estimate the severity of the substance abuse problem?

Learn about alcohol and drug addiction   
Drug addiction is a complex brain disease. It is characterized by compulsive, at times uncontrollable, drug craving, seeking, and use that persist even in the face of extremely negative consequences. Drug seeking becomes compulsive, in large part as a result of the effects of prolonged drug use on brain functioning and, thus, on behavior. For many people, drug addiction becomes chronic, with relapses possible even after long periods of abstinence.
How quickly can I become addicted to alcohol or a drug?
There is no easy answer to this. If and how quickly you might become addicted to a drug depends on many factors including the biology of your body. All drugs are potentially harmful and may have life-threatening consequences associated with their use. There are also vast differences among individuals in sensitivity to various drugs. While one person may use a drug one or many times and suffer no ill effects, another person may be particularly vulnerable and overdose with first use. There is no way of knowing in advance how someone may react.
How do I know if someone is addicted to alcohol or drugs?
If a person is compulsively seeking and using a drug despite negative consequences, such as loss of job, debt, physical problems brought on by drug abuse, or family problems, then he or she is probably addicted. Those who screen for drug problems, such as physicians, have developed the CAGE* questionnaire. These four simple questions can help detect substance abuse problems:
        1.) Have you ever felt you ought to Cut down on your drinking/drug use?
        2.) Have people ever Annoyed you by criticizing your drinking/drug use?
        3.) Have you ever felt bad or Guilty about your drinking/drug use?
        4.) Have you ever had a drink or taken a drug first thing in the morning to steady your nerves or get rid
        of a hangover (Eye-opener)?
* Adapted from: Ewing JA. Detecting Alcoholism: The CAGE Questionnaire. JAMA, 252:1905-1907, 1984.
What are the physical signs of abuse or addiction?
The physical signs of abuse or addiction can vary depending on the person and the drug being abused. For example, someone who abuses marijuana may have a chronic cough or worsening of asthmatic conditions. THC, the chemical in marijuana responsible for producing its effects, is associated with weakening the immune system which makes the user more vulnerable to infections, such as pneumonia. Each drug has short-term and long-term physical effects, stimulants like cocaine increase heart rate and blood pressure, whereas opioids like heroin may slow the heart rate and reduce respiration.
-Alcohol is considered a drug.

Information from: The National Institute on Drug Abuse (NIDA). E-mail  Information@lists.nida.nih.gov or call 301-443-1124. The source for this article is listed below.