If you’re worried about your own drug or alcohol use, here are some of the warning signs to look for:

Often taking more of the substance for a longer period than intended
Ongoing desire or unsuccessful efforts to reduce use
Great deal of time spent to obtain, use, or recover from substance
Craving the substance
Failure to fulfill obligations at work, home, or school as a result of continued use
Continued use despite ongoing relationship problems caused or worsened by use
Giving up or reducing social, occupational, or recreational activities because of use
Repeated use in physically dangerous situations (like drinking or using other drugs while driving)
Continued use despite ongoing physical or mental health problems caused or worsened by use
Developing tolerance (feeling less effect from the substance with continued use)
Withdrawal symptoms if substance is reduced or discontinued

There are many signs, both physical and behavioral, that may indicate drug use in a friend or family member. Each drug has its own unique manifestations, but there are some general indications that a person is using drugs: