Drinking five or more drinks for men (four for women) in any one sitting is considered binge drinking, which can be harmful to your physical and mental health in many different ways. If you even occasionally engage in binge drinking, your alcohol use is by definition alcohol abuse.
For many legal substances, the line between use and abuse is not clear. Is having a couple of drinks every day after work to unwind use or abuse? Is drinking two pots of coffee in the morning, to get your day started, use or abuse? Is smoking a pack of cigarettes a day substance abuse?
Generally, in these situations, only the individual him/herself can determine where use ends and abuse begins. The question to ask yourself is, "Is this causing me or my family any harm?"
Substance abuse can simply be defined as a pattern of harmful use of any substance for mood-altering purposes. "Substances" can include alcohol and other drugs (illegal or not) as well as some substances that are not drugs at all.
"Abuse" can result because you are using a substance in a way that is not intended or recommended, or because you are using more than prescribed. You may be self-medicating with alcohol or drugs in order to deal with mental health concerns.