How can I tell if someone is using drugs?

There are some signs and behaviours that may raise concern to whether your child is using drugs, however many of these behavioural changes are also common among developing adolescents so it is important not to jump to conclusions. Some signs of drug use may include: 

  • Withdrawal from friends and family;
  • Change in friendships or problems with friends;
  • A drop in grades at school;
  • Signs of depression, agitation or hostility;
  • An increase in borrowing money;
  • Evidence of drug paraphernalia or missing prescription drugs.

Some signs that someone may be under the influence of a drug include:

  • Dilated (enlarged) pupils, bloodshot or glassy eyes;
  • Increased energy and confidence;
  • Loss of inhibitions, loss of coordination;
  • Aggressive behaviour;
  • Trembling, twitches, paranoia (e.g. being extremely suspicious);
  • Auditory or visual hallucinations (e.g. hearing or seeing things that aren’t really there);
  • Nausea and vomiting;
  • Complaints of stomach cramps, blurred vision, headaches or dizziness;
  • Exhaustion, fatigue or insomnia;
  • Irritability and moodiness;
  • Changes to eating patterns such as reduced or increased appetite;
  • Anxiety symptoms such as panic attacks, dizziness, sweating, dry mouth, muscle aches and headaches.

It’s important to remember that drugs can affect different people in different ways. For more information about different drugs and their specific effects, see our drug factsheets page.

If you are worried that your child may be using alcohol or other drugs, Positive Choices provides tips to help you start a conversation, information about the warning signs that someone might be dependent on a drug and where to get help and advice.


Evidence Base

This factsheet was developed following expert review at the NHMRC Centre of Research Excellence in Mental Health and Substance Use and National Drug and Alcohol Research Centre, UNSW.