No matter how hard a person tries to hide that they are abusing drugs and/or alcohol, substance abuse is almost impossible to hide entirely. Usually friends and family members are the first to notice that something is just not right with their friend or family member. There are several signs to look for if you suspect someone you care about is abusing drugs or alcohol.
One sign that a person is becoming addicted to drugs or alcohol is if that person gives up activities that he once enjoyed. For example, a teen that at one time played basketball every chance he got suddenly stops playing altogther. That is a rather major warning sign that something is going on that needs to be investigated further.
Personality changes are not uncommon in substance abusers. If a normally happy person suddenly becomes irritable and aggressive, you may have just cause for concern. Many substance abusers become increasingly forgetful, as well.
If you notice someone getting drunk or high regularly, you should pay close attention, especially if they start avoiding their friends or family in order to drink or use drugs.
If someone you know displays just one of these warning signs, there is more than likely no reason to worry. For example, if your best friend becomes forgetful, chances are there is another cause of his forgetfulness, such as stress at work or home. However, if your friend displays several of these behaviors in conjunction with each other, you have every right to be alarmed, particularly of these behavior changes occur suddenly.