Spotting drug use

What should raise concern, whatever the substance

• Sleep: sleepless nights, impossible mornings, a completely shifted rhythm.
• Money: sums disappearing, objects sold, repeated borrowing, debts.
• Company: a clean break with old friends, new contacts never met in person, calls and messages that make the person leave the room.
• School or work: absences, lateness, results falling fast, abandoning activities that used to matter.
• Mood: irritability, secrecy, aggression at an ordinary question, euphoria alternating with collapse.
• The body: weight loss, grey complexion, neglected hygiene, abnormally large or small pupils, unexplained marks.

None of this is specific. Depression, bullying, a break-up or a first psychiatric episode produce exactly the same signs — one more reason to talk rather than accuse.

The objects that tell you something

• Rolling papers, a grinder, card filters, many lighters: cannabis.
• Small bags, rolled notes, scratched cards, powder traces: cocaine, ketamine, amphetamines.
• Small silver metal cartridges, balloons, coloured canisters: nitrous oxide.
• Small bottles with a chemical smell: poppers.
• Bottles of colourless liquid, pipettes, needleless syringes: GHB or GBL.
• Blackened spoons, burnt foil, tourniquets, syringes: opioids injected or smoked.
• An unfamiliar vaping device, unlabelled e-liquid bottles: synthetic cannabinoids. This is the hardest case, because there is no smell and no suspicious object.
• Blister packs outside any treatment, empty boxes, prescriptions from several doctors.

Detection windows in practice

Orders of magnitude. Real values depend on dose, frequency, body weight and the cut-off of the test used.

What tests are worth, and what they cost

Urine tests sold in pharmacies detect the classic families and nothing else: not synthetic cannabinoids, not fentanyl, not GHB, not most novel substances. They give false positives — some painkillers, antidepressants or decongestants are enough — and false negatives as soon as the cut-off is wrong. A positive says nothing about when, how much, or whether there is dependence.

Above all, testing your child without their agreement has a cost that is not on the box: trust. Once a secret test is discovered, the conversation becomes far harder, and what the teenager mostly learns is to hide better. The teams who see these families almost always advise starting with an appointment together at a young people's substance service rather than with a test bought at a chemist.