What are substance use disorders?

Substance use disorders (SUDs) occur when a person's use of alcohol, tobacco, opioids, stimulants, cannabis or other drugs causes health problems or distress. They range from mild (problematic use) to severe (addiction/dependence). ICD-11 classifies SUDs across all substance categories. This hub focuses on illicit drug use disorders; alcohol and tobacco have dedicated GMJ News hubs.

How many people have drug use disorders?

UNODC estimates 35.6 million people globally have drug use disorders — approximately 1 in 7 of the 292 million people who used drugs in 2021. The largest disorder categories are opioids (60 million users, the most dangerous category), amphetamines and cannabis. Only 1 in 8 people with drug use disorders receives any treatment — the largest treatment gap of any health condition.

What is the opioid crisis?

The opioid crisis is a global epidemic of opioid use disorders and overdose deaths — initially driven in North America by overprescription of pharmaceutical opioids, then accelerated by illicit opioids (heroin and now illicitly manufactured fentanyl). Illicit fentanyl — 50-100 times more potent than morphine, often mixed into other drugs without users' knowledge — now dominates overdose deaths. The US alone recorded over 80,000 opioid overdose deaths in 2023. Canada, Europe and Australia face similar crises.

Naloxone is a fast-acting opioid antagonist that reverses opioid overdose within 2-3 minutes when administered intranasally or by injection. It is safe, inexpensive and included on the WHO Essential Medicines List. Wide distribution to people who use opioids, their families, first responders and the general public is the most impactful immediate overdose prevention strategy. In many jurisdictions, naloxone is now available over-the-counter.

What is opioid agonist therapy?

OAT (methadone or buprenorphine/naloxone) is the gold standard treatment for opioid use disorder. It reduces illicit opioid use by eliminating cravings and withdrawal, and reduces overdose mortality by approximately 59% (Cochrane). OAT is an evidence-based medical treatment — not a substitute addiction. Retention in OAT programmes is associated with dramatically reduced mortality, HIV transmission, criminal activity and social deterioration. WHO and UNAIDS recommend OAT as an essential HIV prevention intervention.

What is harm reduction?

Harm reduction is a public health approach aiming to reduce the harmful consequences of drug use without necessarily requiring abstinence. Evidence-based interventions: needle and syringe programmes (NSP) — reducing HIV and HCV among people who inject drugs by >50%; opioid agonist therapy (OAT); naloxone distribution; drug consumption rooms (supervised injection facilities); fentanyl test strips (detecting fentanyl contamination in drug supplies). WHO, UNAIDS and UNODC recommend harm reduction as essential public health practice.

What is the fentanyl crisis?

Illicitly manufactured fentanyl (IMF) — synthesised primarily in Mexico from Chinese precursor chemicals — has contaminated illicit drug supplies across North America, Europe and beyond. It is 50-100 times more potent than morphine; microgram-level doses cause overdose. IMF is now found in heroin, cocaine, methamphetamine and counterfeit pills — killing people who are unaware of contamination. Fentanyl test strips allow users to check drug supplies and reduce overdose risk.

What is the methamphetamine crisis?

Methamphetamine (meth, crystal meth, "yaba") is now the most widely manufactured and used illicit stimulant globally — with UNODC estimating 36 million users. Meth supply has increased dramatically in East and Southeast Asia (from Myanmar), North America and Australia. Meth causes psychosis, cardiovascular disease, dental destruction and severe addiction. No pharmacological treatment for meth use disorder has been approved — behavioural therapies are the primary treatment.

Should drug use be decriminalised?

WHO, UNAIDS, UNODC and the Lancet Commission on Drug Policy recommend decriminalising personal drug use and possession as a prerequisite for effective public health responses. Criminalisation drives people who use drugs away from health services, increases HIV and HCV transmission risk, and does not reduce drug use. Portugal's 2001 decriminalisation — combined with treatment expansion — reduced drug-related deaths by 90% and HIV infections among people who inject drugs dramatically. Several countries and US states have adopted similar approaches.

How does GMJ News cover substance use?

GMJ News covers UNODC World Drug Report data, opioid crisis developments, harm reduction policy, OAT access and drug policy reform evidence. Georgia has significant challenges with opioid use (heroin has historically been prevalent) and is implementing OAT programmes — directly relevant to PHIG's public health work and the Georgian Medical Journal's coverage of addiction medicine.

Home › Topics › Substance Use and Addictions

Substance Use and Addictions

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Substance use disorders affect an estimated 35.6 million people globally with drug use disorders and are responsible for 1.18 million opioid overdose deaths per year — a burden driven by the global opioid crisis, illicit fentanyl, and the massive unmet need for treatment in all world regions (WHO/UNODC). Alcohol use disorders (covered separately by GMJ News) and tobacco (separately covered) compound the substance use burden. The WHO ATLAS on Substance Use Disorders and evidence-based harm reduction strategies — needle and syringe programmes, opioid agonist therapy, naloxone distribution — save lives when implemented.

Key messages

35.6 million with drug use disorders

35.6 million people globally have drug use disorders — yet only 1 in 8 receives treatment. The opioid crisis, illicit fentanyl contamination and the global methamphetamine surge are driving deaths to record levels (UNODC).

Opioid overdose — 1.18 million deaths/year

Opioid use disorders and overdose cause approximately 1.18 million deaths per year — predominantly from illicit opioids (heroin, illicit fentanyl) in North America and from prescribed opioid overuse elsewhere (WHO/UNODC 2022).

Harm reduction saves lives

Evidence-based harm reduction — needle and syringe programmes (NSP), opioid agonist therapy (OAT, methadone/buprenorphine), naloxone distribution and drug consumption rooms — significantly reduces overdose deaths, HIV and HCV transmission, and mortality.

Treatment gap

Only 1 in 8 people with drug use disorders receives treatment globally. Barriers include: criminalisation of drug use; stigma; limited treatment services; and high cost. WHO recommends decriminalisation of personal drug use as a prerequisite for effective public health responses.

UNODC World Drug Report

The UNODC World Drug Report — published annually — is the most comprehensive global assessment of drug use, trafficking and policy. The 2023 report documented 292 million drug users globally (a 23% increase over a decade) and record drug supply.

Alcohol and tobacco

Alcohol and tobacco use disorders are separately covered in dedicated GMJ News hubs. This hub focuses on illicit and pharmaceutical drug use disorders — predominantly opioids, stimulants (amphetamines, cocaine), cannabis and sedatives.

Key statistics

35.6M

people with drug use disorders

UNODC 2022

292M

people used drugs in 2021

UNODC 2023

1.18M

opioid-related deaths/year

WHO/UNODC

1 in 8

with drug disorders receives treatment

UNODC 2022

+23%

increase in drug users over a decade

UNODC 2023

60mg

of methadone/day reduces opioid overdose by 59%

Cochrane

Drug users globally by substance type (millions) — UNODC 2023 World Drug Report

Source: UNODC World Drug Report 2023. Cannabis dominates by users; opioids dominate by deaths.

Glossary of key terms

Opioid use disorder
WHO ICD-11A pattern of opioid use causing clinically significant impairment or distress, with strong desire to take opioids, difficulty controlling use, continued use despite harm and physiological dependence. Treated with opioid agonist therapy (methadone or buprenorphine).

Opioid agonist therapy (OAT)
WHOPrescribed methadone or buprenorphine for opioid use disorder — reducing cravings and withdrawal, eliminating the need for illicit drug use. Reduces overdose death by 59% (methadone, Cochrane). WHO Essential Medicines. A core harm reduction and treatment intervention.

Naloxone
WHO/FDAA fast-acting opioid antagonist that reverses opioid overdose within minutes when given intranasally or by injection. WHO Essential Medicine. Wide distribution to people who use opioids, their families and first responders is the primary overdose prevention strategy.

Harm reduction
WHO/UNAIDSPolicies and programmes aimed at reducing the harmful consequences of drug use — without necessarily requiring abstinence. Key interventions: needle and syringe programmes (NSP); opioid agonist therapy (OAT); naloxone distribution; drug consumption rooms; fentanyl test strips.

Fentanyl
DEA/WHOA synthetic opioid 50-100 times more potent than morphine. Illicitly manufactured fentanyl (IMF) now contaminates drug supplies across North America, Europe and beyond — causing the majority of opioid overdose deaths. Fentanyl test strips detect contamination.

UNODC
UNUN Office on Drugs and Crime — the lead UN agency on drug policy and crime. Produces the annual World Drug Report, coordinates international drug control and supports national drug policy reform.