The following signs and symptoms are indicative of  substance abuse (note that not all of these symptoms will be present in all cases):

• changes in mood and mood swings;
• a less negative attitude to alcohol and drugs (thinking or saying "there is nothing wrong with  drinking or taking drugs");
• deterioration in appearance and personal hygiene;
• red, inflamed eyes;
• secrecy about friends and their joint activities;
• unexplained absence from home, the keeping of strange hours;
• poor motivation, a negative attitude towards school, poor academic performance and poor time management;
• becoming socially withdrawn;
• general lethargy and sleepiness; feeling tired; difficulty waking up in the morning;
• weight loss.

If you are concerned about a friend or you think that you might have a problem get help.