Each chemical substance has a set of characteristic withdrawal symptoms that vary per drug. Alcohol withdrawal is often marked by shakiness and anxiety, and cocaine withdrawal usually leaves you feeling depressed and tired. Withdrawal from opiate pills will give you a headache and stomach cramps. These withdrawal symptoms occur from repeated use and aren't to be confused with a hangover from a big night out. If you're experiencing severe withdrawal symptoms, or you're using more of the same substance to avoid withdrawal, this is a sign of addiction.