What are the signs and symptoms of substance abuse?
The signs and symptoms of substance abuse show in behaviour, body and mood.
Secrecy about time and money, changed sleep and appetite, and using that carries on despite the harm. Doctors diagnose a substance use disorder when 2 or more of the 11 DSM-5 symptoms appear within 12 months.
Signs and symptoms of substance abuse in the body, behaviour and mood
Most people show some signs of each kind, and families usually notice the behavioural signs of drug use before the physical ones. NIDA’s core test is simple: a drug problem is present when a person keeps using even though it is harming their life.
Signs of addiction
Early signs of drug addiction
- Cravings that crowd out other thoughts
- Tolerance: more of the substance needed for the same effect
- Money going on the substance that should be going elsewhere
- Work, study or family duties slipping
- Pulling away from friends, family and colleagues
Physical symptoms of substance abuse
- Bloodshot eyes, or pupils that are dilated or pinpoint depending on the substance
- Sudden changes in weight or appetite
- Sleep that is too little, too much, or at odd hours
- Shakiness, sweating or nausea once the substance wears off
- A smell on breath or clothing, masked with mints and perfume
Behavioural signs
- Secrecy about time, money, or who they have been with
- Defensiveness out of proportion when the subject comes up
- Using where it used to be off limits, such as before work or while driving
- Cash that goes missing, or prescriptions from more than one doctor, a pattern NIDA calls “doctor shopping”
Psychological signs
- Mood that tracks access to the substance more than the day’s real events
- Denial or minimising when someone raises a concern
- Guilt or shame about the using, alongside a strong pull to keep doing it
Symptoms of drug use by substance, from alcohol to tik
| Substance | Signs that often show up |
|---|---|
| Alcohol | Drinking earlier in the day, rising tolerance, morning shakes, gaps in memory. More in our guide to the signs of alcoholism. |
| Tik (methamphetamine) | Alertness, talkativeness and no appetite while using; with time, tooth decay, insomnia, paranoia and seeing or hearing things that are not there. See what tik does to a person. |
| Cocaine and other stimulants | Dilated pupils and high energy that fade into a flat comedown, weight loss, and nosebleeds with snorted cocaine. More on the signs of cocaine addiction. |
| Opioids and prescription pain pills | Pinpoint pupils, drowsiness, constipation, and prescriptions from more than one doctor. |
| Benzodiazepines and sleeping pills | Drowsiness, problems with movement and memory, and slowed breathing, which mixing with alcohol or opioids makes worse, per NIDA’s drug charts. |
| Cannabis | Bloodshot eyes and a bigger appetite while using; irritability and poor sleep within days of stopping. See whether you can get addicted to cannabis. |
Three rows of that table, tik, alcohol and cannabis, cover most people entering specialist treatment in the Western Cape. In July to December 2025, tik was the main drug for 34% of people admitted there, ahead of alcohol at 25% and cannabis at 23%, according to SACENDU2, the South African Medical Research Council’s drug-use monitoring network.
Is it addiction or a rough patch? The 11 DSM-5 criteria
One sign on its own proves little: a hard month at work can explain poor sleep or a short temper. What doctors look for is a pattern, and the DSM-5 lists eleven possible symptoms in four groups. Impaired control means using more than planned, failing to cut down, and craving. Social impairment means duties and relationships slipping. The other two are risky use and physical dependence (tolerance and withdrawal). The same list applies to alcohol, cocaine, cannabis or a prescription medicine.
Two or more of these within 12 months is a substance use disorder. The American Psychiatric Association calls two to three symptoms mild, four to five moderate, and six or more severe.
Mild substance use disorder2 to 3 symptoms
Severe substance use disorder6 or more
Out of 11 possible symptoms in the DSM-5 framework for substance use disorder.
Source: MSD Manual Professional Edition
Can someone be dependent and still function normally?
Yes. The mild end of the scale fits around a job and a family: someone can meet the criteria while still working, parenting and paying every bill on time. Tolerance builds slowly, so the people around them adjust without noticing.
How do the signs of drug use show in teenagers?
The teenage brain is still developing, so drug use at this age can leave a longer-lasting mark, according to NIDA.
What often shows up first in teenagers
- A different group of friends than before
- Falling grades or missed classes, where school used to be steady
- Losing interest in a favourite sport or hobby
- Not caring about appearance the way they used to
- Sleep and eating that suddenly look different
List from NIDA’s guide for parents and educators.
For anyone under 18, start with their doctor or a child and adolescent specialist. Renewed Life Center treats adults aged 18 and over.
Where do substance use and mental health meet?
Often in the same person. Of US adults with another mental disorder, 35% also have a substance use disorder, NIDA reports from the 2023 National Survey on Drug Use and Health.
The link runs both ways. Some people start using because they already feel anxious, flat or unsafe, and the substance takes the edge off. Others develop low mood because of the using: repeated use changes the brain circuits for reward, stress and self-control, which is why NIDA describes addiction as a brain disorder.
Indications of mental illness
- Trouble concentrating, or a mind that feels foggy
- Restlessness, an inability to settle
- Racing thoughts or speech that speeds up
- Swings between very high and very low moods
- Sleep, energy or eating that changes for weeks at a time
- Trouble relating to people, or reading what they mean
When signs from this list show up alongside the ones above, the drug use and the mood problem may be feeding each other, and NIDA’s advice is that it is usually better to treat them at the same time rather than separately. At Renewed Life Center the addiction and the depression, anxiety or trauma under it are treated together; our page on dual diagnosis treatment in Cape Town explains how.
Self-medication: what are the possible causes of substance abuse?
Many causes of substance abuse come down to self-medication: using alcohol, pills or drugs without professional oversight to dull emotional or physical pain. The psychiatrist Edward Khantzian set out the idea in 1985 in the American Journal of Psychiatry. People who suffer with painful feelings are predisposed to addiction, he argued, and the drug a person picks is not chosen at random.
The deeper causes are often older than the first drink: abuse at home, a parent who drank, grief, untreated anxiety, chronic pain, or years of long hours and constant pressure.
When does self-medication become substance abuse?
When the substance has a job to do. A glass of wine with dinner is one thing. A drink to get through the evening, a pill to switch the mind off, a line to face the meeting: that is a substance doing a job. If the honest answer to “what is it for?” is “to cope”, that is the part worth talking through with us.
Take the substance away and leave that job undone, and the old problem is waiting the moment sobriety gets hard. Stopping is half of treatment; the other half is the anxiety, grief or pressure the substance was keeping quiet.
Signs that someone needs emergency help
Some signs mean the person needs medical help now. With opioids, sleeping pills and alcohol, the main danger is breathing that slows down or stops.
Signs of an opioid overdose
- Unconscious, or cannot be woken up
- Slow, shallow breathing, or choking and gurgling sounds
- Skin that looks discoloured, especially around the nails or lips
- Small, pinpoint pupils that do not react to light
List from the CDC. For alcohol, the NIAAA adds vomiting, clammy skin and fewer than eight breaths a minute.
Someone who cannot be woken, is breathing slowly after using, has a seizure, is confused and hallucinating after suddenly stopping drinking, or talks about ending their life is a medical emergency: get emergency help now rather than waiting for a reply from us. Do not assume they are sleeping it off, and stay with them until help arrives.
What should you do once you notice these signs?
Write down what you have seen, talk it through with someone who treats addiction before you raise it, and decide what you are asking for. A written record and one small request work better than a general accusation.
Expect denial. It is one of the psychological signs listed above, and “I’m fine” or “you’re overreacting” is a common first answer. Dates and events are harder to argue with than a label: “you missed Thursday’s school run and the car smelt of drink” is a different conversation from “you’re an addict”.
Four steps before you say anything
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Write it down
Dates, amounts, specific incidents: detail somebody could check. You do not need proof to ask for advice. A few notes and one or two incidents are enough for a first conversation, and you can write to us even before you have them.
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Talk it through with us first
If the person is an adult, contact our team with what you have noticed, and we will talk through what could help and what treatment would involve. You can do this before they have agreed to come.
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Decide what you are asking for
An assessment is an easier yes than a confession. Ours takes 45 to 90 minutes with our counselling team, before any admission.
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Have the next step ready
Know who you will call if they agree, so a yes can turn into a call the same day.
One safety rule comes first. If someone drinks every day, or takes benzodiazepines, sleeping tablets, mandrax, GHB, codeine or other opioids, they should not stop suddenly on their own. The NHS warns that stopping drinking suddenly can be very dangerous for someone dependent on alcohol, and the FDA that stopping benzodiazepines abruptly can cause seizures. Whether a medical detox is needed is a decision for a medical team after an assessment. Our guide on how to talk to a loved one about rehab covers what to say and what to do if the answer is no.
Nobody has to lose a job or a marriage first. The mild end of the DSM-5 scale is still a substance use disorder, and treatment can start there, while the person still has work, a home and people who noticed.
How Renewed Life Center helps once you have noticed the signs
When you write to us, you describe what you have seen and we talk through the next steps for treatment. The first conversation is free and confidential, takes 20 to 40 minutes by WhatsApp, video or phone, and we reply the same day. It is often with John Roberts, our Senior Recovery Specialist and Operations Manager, who has 39 years in recovery.
Renewed Life Center is a residential centre for adults in Lakeside, Cape Town, and treatment here works on the using and on what it was doing for the person. Ruby Weber, the psychologist who heads psychology at the centre, has more than 20 years in the addictions field and leads the psychological side of our dual diagnosis work. Each person’s own counsellor works with them one-to-one every week, alongside group work every weekday. The methods include CBT and DBT for thoughts and urges, schema therapy for old patterns, and EMDR and TRE for trauma; 12-step meetings take place in the evenings.
A doctor examines each person after they arrive, and if they need a detox, our medical team runs it. Nikki Edwards runs the programme as Programme Director and Clinical Manager; with 11 years of her own recovery, she knows those first weeks from the inside.
Families stay part of it. Relatives join a support group by video every week, visits are possible from the first week, children can visit, and relatives can have sessions of their own. The aim is a home where evenings no longer turn on the drinking or using, and every discharge includes a written relapse-prevention plan built for that home.
Phones and laptops stay with the person, and they can keep working remotely during treatment; how much work fits around the programme is agreed with their counsellor. Admission can be immediate and typically happens within three days of first contact. The fee depends on the programme and how long the person stays; we give it on the first call and send it in writing the same day.
Noticed the signs and not sure what to do next? Talk to our team on WhatsApp.Noticed the signs and not sure what to do next? Call +27 79 880 0045, free and confidential.
What else do families ask?
Signs are what others see (secrecy, missing money, mood swings), symptoms are what the person feels (cravings, tolerance, withdrawal), and the causes are usually older: anxiety, depression, trauma, grief or chronic pain that the substance was quietening.
Addiction is the everyday name for a moderate or severe substance use disorder: someone keeps using even though it is harming their life, in NIDA’s words. The substance has started to set the timing, the amount and the priorities.
In the short term, the effects of drug and substance abuse depend on the drug: drowsiness with opioids and sedatives, a racing high and crash with tik and cocaine. With time come damaged sleep, mood, memory, relationships and finances, and with some drugs psychosis, heart problems or overdose. Our page on the long-term effects of drugs goes substance by substance.
Stopping is the first part; staying stopped means dealing with what the drug was doing for the person. Our page on the CAT drug (methcathinone) covers it in detail. If alcohol, sleeping tablets or other sedatives are also taken every day, do not stop suddenly on your own: talk to our team about the next steps for treatment first.
Seeing these signs in someone you love? Talk it through with us.
A free, confidential first conversation, and we reply the same day. A relative can talk to our team before the person has agreed to come. We treat the using and what sits under it together, and admission typically happens within three days of first contact.
Writing for someone else? You do not need their permission to message us.
or call +27 79 880 0045
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Sources
- MSD Manual Professional Edition, Substance Use Disorders; American Psychiatric Association, DSM-5 fact sheet
- SAMRC, SACENDU research update, July to December 2025
- NIDA: Co-Occurring Disorders and Health Conditions; Drugs, Brains, and Behavior; Adolescent Brain; Signs of a Problem With Drugs; drug facts and charts
- Khantzian EJ, The self-medication hypothesis of addictive disorders, American Journal of Psychiatry, 1985
- CDC, Signs of an Overdose; NIAAA, Understanding the Dangers of Alcohol Overdose
- NHS, Alcohol use disorder (page reviewed 24 April 2026); FDA, boxed warning for the benzodiazepine drug class
This article is general information, not medical advice.