Recognising the Signs of Drug Use

Drug use can often be recognised earlier than many people think, because the body and behaviour respond sensitively to psychoactive substances. Visible changes in the eyes, skin, weight or movement can be early warning signs.

Emotional fluctuations, social withdrawal and performance problems also become more common. Because these signs vary and differ by drug, knowing typical patterns can be useful. This helps relatives respond sooner and offer timely support.

Key points

• Physical, psychological and social changes are often the first indications of drug use.
• The eyes, skin, weight and motor function respond particularly quickly to substances.
• Mood swings, anxiety or sleep disturbances often accompany these changes.
• Changes in behaviour and everyday life usually develop gradually but noticeably.
• The earlier warning signs are recognised, the better the chances of obtaining help.

How can you tell whether someone is using drugs?

Drug use can be recognised through typical physical signs such as altered pupils, skin problems or weight loss, alongside psychological and social changes including mood swings, restlessness, withdrawal or declining performance.

Physical changes in the eyes

Altered pupils are among the most common indications of drug use. They may be markedly dilated or unusually constricted. Red or glassy eyes are also common because many substances affect blood flow or tear production.

These changes may appear suddenly and vary several times throughout the day. They are often particularly noticeable in bright light. A fixed or unfocused gaze may also appear. Taken together, these eye changes can look unnatural and are therefore considered early warning signs.

Noticeable changes in breathing, the body and skin

Drugs directly affect metabolism, skin and breathing. This can produce characteristic smells that cannot be explained by ordinary body odour. Some substances cause pronounced sweating, making changes more noticeable.

Scratch marks often result from dry or irritated skin that the person repeatedly scratches. Injection sites leave small scars or fresh marks, commonly on the arms, backs of the hands or concealed areas. Dental health may also deteriorate quickly. Overall, the person may appear more physically neglected and strained.

Changes in weight and physical stability

Many drugs affect appetite and energy expenditure. People may therefore lose weight quickly or show a marked lack of appetite. As the body uses its reserves, they can appear weakened. Trembling or uncontrolled movements may occur at the same time.

These arise from the substances’ effects on the nervous system, making movement seem unsteady or frantic. Posture may also change through restlessness or weakness. Such changes usually become clearly noticeable over several weeks and are considered important indications of longer-term use.

Psychological reactions and pronounced mood swings

Drugs directly influence emotions, potentially producing extreme mood swings ranging from euphoria to profound low mood. These changes often occur abruptly. Nervousness and general inner restlessness are equally common.

Many people sleep poorly or very little, further increasing psychological strain. Concentration problems are also typical as the brain is placed under greater demand. Anxiety, paranoia or even hallucinations may occur. All these symptoms indicate considerable psychological distress and should be taken seriously.

Social changes and withdrawal

Drug use also affects social relationships. Many people withdraw because they want to conceal their behaviour or feel uncomfortable. They neglect their appearance and previous routines, while conflicts with others increase.

Friendship groups often change as contact with people using other substances increases. Familiar people and places are avoided. A growing need for money may also lead to unusual behaviour or unexplained spending. These social changes usually develop gradually but consistently.

Declining performance, loss of motivation and daily difficulties

Drugs impair attention, memory and motivation, causing school or work performance to deteriorate. Tasks become more difficult and are abandoned more frequently. The ability to concentrate also visibly declines.

People lose interest in previous hobbies and activities. Everyday life becomes increasingly chaotic as priorities slip. Appointments are forgotten or deliberately avoided. Overall, there is a clear loss of structure and resilience.

Looking at the eyes: miosis versus mydriasis

The eyes are often the most revealing signs of drug use. Pay close attention to the pupils: stimulants such as cocaine, speed (amphetamines) or crystal meth usually cause mydriasis, meaning markedly dilated pupils that barely respond to light. In contrast, opiates such as heroin or methadone, or painkillers, often cause miosis: pinpoint, constricted pupils.

Cannabis often causes red conjunctivae or glassy eyes, while pupil responses may vary. A fixed gaze or rapid eye movements (nystagmus) are further warning signs that should not be ignored.

Suspicious objects: what is in the room?

Relatives often discover drug paraphernalia before noticing physical symptoms. Typical objects suggesting use include small resealable plastic bags with powder residue or traces inside. Cannabis use often involves long rolling papers, cardboard filter tips or a grinder.

Pieces of aluminium foil with black soot marks, or shortened straws and tubes, may indicate smoking or snorting drugs such as heroin or crystal meth. Soot marks on lighters or spoons are also classic indications of hard drug use.

Social warning signs and financial problems

Alongside physical signs, behavioural changes are a major warning signal. Drug use is expensive and time-consuming. You may notice missing money, disappearing valuables or repeated requests to borrow money.

Another indication is withdrawal from established friends and contact with an entirely new, often secretive group. Aggressive defensiveness, fabricated stories or complete withdrawal in response to questions often serve as protective mechanisms for addiction. Sudden drops in school or work performance frequently complete this picture of social deterioration.

Conclusion

Knowing the typical physical, psychological and social indications of drug use helps identify warning signs early. Because many symptoms develop gradually, paying attention to changes is worthwhile. Empathetic conversations and prompt support can be decisive in helping people find a way out of dependence. The sooner help is provided, the greater the chance of a stable future.

Sources:

• BZgA Drug Encyclopaedia: Effects and Risks in Detail
• German Centre for Addiction Issues: Information About Illegal Drugs
• Keine Macht den Drogen: Guidance for Relatives and People Affected

---

FAQ

How can I recognise drug use from someone’s eyes?

Drug use often causes pupil changes: stimulants such as cocaine or speed usually produce markedly dilated pupils, whereas opiates cause very small, constricted pupils. Red or glassy eyes, particularly with cannabis, are also common warning signs.

Which objects suggest drug use?

Typical items include small plastic bags, snorting tubes, aluminium foil with burn marks and syringes. Long rolling papers, grinders or unusually large numbers of lighters may also indicate drug possession.

How does someone who uses drugs behave?

People using drugs often show pronounced mood swings, from euphoria to aggressive irritability or profound low mood. They frequently withdraw socially, neglect hobbies and respond to questions with lies or defensiveness.

Can you smell drug use?

Yes, certain drugs have a characteristic smell. Cannabis smells sweet and herbal, often resembling burnt grass. Drugs such as crystal meth can cause a chemical body odour reminiscent of cat urine or ammonia.

What are the signs of cocaine use?

Cocaine use often causes hyperactivity, excessive talking, overconfidence and dilated pupils. Intoxication is frequently followed by exhaustion, irritability and depressed mood.

How can I recognise cannabis use in teenagers?

Common signs include red eyes, sudden intense hunger, silly behaviour or slower reactions. Over time, lack of motivation, concentration problems and declining school performance may occur.

What should I do if I find drugs belonging to my child?

Stay calm and talk when they are sober, without immediately making accusations. Seek professional support from a drug counselling service to assess the situation properly.

Do drugs change the appearance of the skin?

Yes. Crystal meth or heroin in particular can cause major deterioration, with spots, inflammation or wounds from scratching. A pale, grey complexion and dark circles under the eyes are also common.

Are mood swings always a sign of drug use?

No. Mood swings can also be caused by puberty, stress or mental health conditions. However, when they occur alongside other signs such as financial problems or altered pupils, drug use is a reasonable concern.

How long are drugs detectable?

Detection periods vary considerably. Most drugs are detectable in urine for several days, while cannabis can remain detectable for several weeks with continuous use. Drugs can often still be detected in hair months later.