If your teen has all the aforementioned warning signs and is not yet using or experimenting with drugs and/or alcohol, it probably won't be long before they start. Teens who exhibit most or all of the previously mentioned warning signs are not feeling very good about who they are and as a result will have little respect for themselves and others. Once the personal respect is gone, there is not much stopping them from doing self-destructive things such as using drugs. When looking for signs, the main word to keep in mind is "change." It is important to be aware of any significant changes in your teen's physical appearance, personality, attitude or behavior. Some of the most notable physical signs of drug use are: changes in appetite (increase or decrease), diminished physical coordination, inability to sleep, awake at unusual times, unusual laziness, red/watery eyes, pupils larger or smaller than usual, shaking hands, smell of substance on breath/body/clothes, extreme hyperactivity, excessive talkativeness, runny nose, hacking cough, needle marks on lower arm/leg/bottom of feet, nausea/vomiting, excessive sweating and tremors or shakes of hands/feet/head.