Substance Library

Drug & Alcohol Guides, One Substance at a Time

What each substance does, what stopping tends to involve, where the real medical risk sits, and which kind of treatment programs typically handle it.

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What This Guide Covers

Four questions, answered with cited federal data and clinical guidance — every figure attributed to the agency or study it came from.

01How common it is44.6 million people met criteria for a substance use disorder in 2025 — plus current CDC overdose counts by drug class.
02Which withdrawals carry riskAlcohol and sedatives can be life-threatening to stop unsupervised. Risk does not track how bad withdrawal feels.
03How a disorder is diagnosedThe 11 DSM-5 criteria clinicians actually use, and what mild, moderate, and severe mean.
04What treatment existsWhich substances have FDA-approved medication, which are treated behaviorally, and what detox does and does not do.

The Data

The National Picture, in Numbers

Prevalence figures come from SAMHSA's 2025 National Survey on Drug Use and Health, released July 2026 and the most recent edition available, the federal survey used to estimate substance use disorder in the United States. Overdose figures update automatically from CDC's provisional mortality data.

Lead figure

44.6M

Had a substance use disorder

15.3% of people aged 12 or older met criteria in the past year, down from 16.7% in 2021.

25.7M

Alcohol use disorder

8.9% of people aged 12 or older — down from 10.6% in 2021.

26.0M

Drug use disorder

Across all drugs other than alcohol; 7.1 million people had both.

16.0%

Of those who needed treatment got it

7.6 million of the 47.2 million people who needed substance use treatment received any in the past year.

Past-year estimates among people aged 12 or older. Source: SAMHSA, 2025 National Survey on Drug Use and Health.

Use Disorder by Substance

Past-year prevalence, ages 12 and older, 2025. A person can meet criteria for more than one, so these categories overlap.

Substance	People	Share
Alcohol	25.7 million	8.9%
Marijuana	19.3 million	6.7%
Stimulants (CNS)	4.5 million	1.5%
Opioids (any)	4.0 million	1.4%

Source: SAMHSA, 2025 National Survey on Drug Use and Health, Detailed Tables 5.1A and 5.1B (past-year use disorder, ages 12 and older).

Live CDC data

Which Drugs Are Involved in Overdose Deaths

12 months ending December 2025 · 70,735 total deaths

Synthetic opioids (mostly fentanyl)38,506-21.3%
54% of deaths
Psychostimulants (mostly methamphetamine)26,315-11.8%
37% of deaths
Cocaine19,953-10.9%
28% of deaths
Prescription opioids (natural & semi-synthetic)7,148-11.6%
10% of deaths
Methadone3,564+8.5%
5% of deaths
Heroin2,065-26.5%
3% of deaths

Source: CDC/NCHS, VSRR Provisional Drug Overdose Death Counts, predicted 12-month-ending provisional counts, refreshed from CDC monthly. Categories overlap — a death involving more than one drug is counted in each category it involves, so the rows do not sum to the total. Provisional counts are incomplete and are revised as investigations close.

In Depth

Substance by Substance

What each substance does, what dependence tends to look like, how withdrawal unfolds, and — the question people most often arrive with — whether medically supervised detox is indicated and what an inpatient setting actually adds.

Alcohol

Depressants

What it is

Alcohol depresses activity in the central nervous system, producing sedation, disinhibition, and impaired coordination and judgment. It is legal, widely available, and socially embedded, which is part of why heavy use often continues far longer before anyone treats it as a medical problem.

What dependence looks like

With sustained heavy drinking the nervous system adapts by running at a higher baseline, so it takes more alcohol to reach the same effect and the body becomes unsettled without it. A common pattern is drinking earlier in the day to steady tremor or anxiety, which is a sign of physical dependence rather than habit.

Withdrawal

Symptoms typically begin 6 to 12 hours after the last drink with anxiety, tremor, sweating, and nausea. The highest-risk window for withdrawal seizures is roughly 24 to 48 hours, and delirium tremens — confusion, severe agitation, fever, and unstable heart rate and blood pressure — can appear around 48 to 72 hours and is treated as a medical emergency. Sleep disturbance and low mood often persist for weeks.

Read the full Alcohol guide

Benzodiazepines

Depressants

What it is

Benzodiazepines — including alprazolam, clonazepam, diazepam, and lorazepam — are prescription sedatives used for anxiety, panic, insomnia, and seizures. They work quickly and work well, which is exactly why dependence can develop during legitimate, prescribed use.

What dependence looks like

Tolerance to the sedative and anti-anxiety effects can develop within weeks of daily use, and the anxiety that returns between doses is easily mistaken for the original condition getting worse. Dependence here is often a medical event rather than a behavioral one: many people never take more than prescribed and still cannot stop without help.

Withdrawal

Onset depends on the half-life of the specific drug — short-acting benzodiazepines produce symptoms within a day, longer-acting ones can take several days. Symptoms include rebound anxiety and insomnia, tremor, sensory hypersensitivity, and, after sustained use, seizures. Symptoms can persist or recur over weeks, which is why the taper is measured in weeks or months rather than days.

Read the full Benzodiazepines guide

Opioids & Heroin

Opioids

What it is

The opioid category covers heroin, prescription painkillers such as oxycodone, hydrocodone, and morphine, and synthetic opioids including fentanyl. They act on the same receptors to relieve pain and produce sedation and euphoria, so dependence follows a broadly similar pattern across the class even though potency and duration differ enormously.

What dependence looks like

Tolerance builds quickly, and for many people the reason use continues shifts early on — from seeking the effect to avoiding withdrawal. Because short-acting opioids wear off within hours, daily life can narrow to a dosing schedule, which is often the most visible sign to family before anything else.

Withdrawal

With short-acting opioids, symptoms usually start 6 to 12 hours after the last dose, peak between 24 and 72 hours, and ease within four to seven days. The peak involves nausea, vomiting, diarrhea, cramps, chills, insomnia, and restlessness. Longer-acting opioids such as methadone produce a slower, more drawn-out course, and low mood, poor sleep, and craving frequently persist for weeks or months.

Read the full Opioids & Heroin guide

Fentanyl

Opioids

What it is

Fentanyl is a synthetic opioid used medically for severe pain and, in illicitly manufactured form, now present throughout the U.S. opioid supply. NIDA describes it as roughly 50 to 100 times more potent than morphine, and it appears in counterfeit pills and in powder sold as heroin, often without the buyer's knowledge.

What dependence looks like

Because it is short-acting and extremely potent, dependence tends to establish itself faster and dosing intervals are shorter than with heroin or prescription opioids. People who have used fentanyl regularly often describe withdrawal beginning sooner and hitting harder, which shortens the window in which stopping feels possible.

Withdrawal

The symptom picture matches opioid withdrawal generally, but onset is often faster and the course can be less predictable. Fentanyl is fat-soluble and can linger in tissue after heavy use, so symptoms sometimes extend beyond the four-to-seven-day pattern typical of shorter-acting opioids.

Read the full Fentanyl guide

Methamphetamine

Stimulants

What it is

Methamphetamine is a potent central nervous system stimulant that produces prolonged wakefulness, elevated energy and mood, and suppressed appetite. Its effects last far longer than cocaine's, which is why use often unfolds in multi-day runs rather than short episodes.

What dependence looks like

Use frequently escalates into binge-and-crash cycles: days awake with little food or sleep, followed by a heavy collapse. Sleep deprivation and malnutrition compound the picture, and psychiatric symptoms including paranoia and, in some people, stimulant-induced psychosis can appear during heavy use.

Withdrawal

There is no dramatic physical syndrome. What follows is a crash — profound exhaustion, extended sleep, increased appetite — then a longer stretch of low mood, flat motivation, difficulty concentrating, and intense craving that commonly runs one to two weeks and can extend well beyond that.

Read the full Methamphetamine guide

Cocaine

Stimulants

What it is

Cocaine is a short-acting stimulant, snorted as powder or smoked as crack, producing a brief, intense elevation in energy, confidence, and alertness. The effect fades within roughly an hour, which shapes how it tends to be used.

What dependence looks like

The short duration drives repeat dosing within a single session, and sessions often end only when the supply does. Because it is frequently used alongside alcohol, both tend to escalate together, and the cardiovascular strain of heavy use — chest pain, arrhythmia, elevated stroke risk — is a genuine medical concern during use rather than during withdrawal.

Withdrawal

Withdrawal is predominantly psychological: fatigue, heavy sleep, increased appetite, low mood, irritability, and strong craving, typically most intense in the first week. Physical symptoms are mild relative to alcohol or opioids, which is one reason the difficulty of stopping is often underestimated.

Read the full Cocaine guide

Cannabis

Cannabis & Nicotine

What it is

Cannabis acts on the endocannabinoid system, producing relaxation, altered perception, and appetite changes. Products available today are substantially more potent than those of a generation ago, and concentrates are stronger still.

What dependence looks like

Dependence tends to be gradual and easy to explain away, particularly where cannabis is legal. The pattern people describe is a widening role — using to sleep, to manage anxiety, to get through ordinary parts of the day — alongside repeated intentions to cut back that do not hold.

Withdrawal

Symptoms usually begin within a day or two of stopping and are most intense during the first week: irritability, anxiety, disturbed sleep and vivid dreams, reduced appetite, restlessness, and craving. Most symptoms ease over one to two weeks, though sleep disruption can persist longer. Physical complications are uncommon compared with alcohol or sedatives, but the symptoms are frequently underestimated and can still warrant clinical support.

Read the full Cannabis guide

Nicotine & Vaping

Cannabis & Nicotine

What it is

Nicotine is a fast-acting stimulant delivered by cigarettes, vapes, pouches, and smokeless tobacco. It reaches the brain within seconds of inhalation, and that speed is a large part of what makes it so reinforcing.

What dependence looks like

Dependence is typically measured in how soon after waking the first use occurs and how quickly discomfort sets in without it. Vaping has changed the pattern for younger users in particular, because high-concentration products allow near-continuous dosing without the natural break a cigarette imposes.

Withdrawal

Symptoms begin within hours: irritability, anxiety, restlessness, difficulty concentrating, low mood, increased appetite, and disturbed sleep. They are generally most intense in the first week and ease over two to four weeks, while cravings can be triggered by routine and setting long afterward.

Read the full Nicotine & Vaping guide

Side by Side

All Substances Compared

General clinical patterns, not a prediction for any individual. Withdrawal severity depends on how much, how long, prior withdrawal episodes, and other medical and psychiatric conditions.

Substance	Withdrawal risk	Medical detox	Typical acute length	FDA-approved medication
Alcohol	Can be life-threatening	Strongly indicated	3–7 days	Naltrexone, acamprosate, disulfiram
Benzodiazepines	Can be life-threatening	Strongly indicated	Weeks to months (taper)	No approved medication for the disorder
Opioids & heroin	Severe; complications possible	Supervision advised	4–7 days acute	Buprenorphine, methadone, naltrexone
Fentanyl	Severe; complications possible	Supervision advised	Often longer than other opioids	Buprenorphine, methadone, naltrexone
Methamphetamine	Primarily psychological	Supervision advised	1–2 weeks, often longer	None approved
Cocaine	Primarily psychological	Supervision advised	About 1 week acute	None approved
Cannabis	Lower physical risk	Not usually required	1–2 weeks	None approved
Nicotine	Lower physical risk	Not usually required	2–4 weeks	NRT, bupropion, varenicline

The Library

Browse by Substance

Guides are grouped by drug class, because class is what determines how withdrawal behaves, what the medical risk is, and which treatments exist.

Depressants

Alcohol and sedatives, where unmanaged withdrawal carries the most medical risk.

Opioids

Prescription and illicit opioids, withdrawal, and medication-based treatment.

Stimulants

Methamphetamine and cocaine, the comedown, and behavioral treatment.

Cannabis & Nicotine

Everyday substances people still ask for help stopping.

Clinical Reference

Which Withdrawals Carry Medical Risk

This is the single most consequential thing to know before someone stops using, and it is the question most often answered wrong online. Risk is not proportional to how bad withdrawal feels, and no withdrawal is risk-free — anyone stopping after regular use should check in with a clinician first.

Alcohol

Beer, wine, spirits

Can be life-threatening

Tremor, sweating, and anxiety can progress to seizures and delirium tremens in people with heavy, sustained use. Guidance treats unmanaged alcohol withdrawal as a potential medical emergency. Stopping should be planned with a clinician.

Sedatives & benzodiazepines

Xanax, Klonopin, Valium, Ativan

Can be life-threatening

Abrupt discontinuation after sustained use can produce seizures. Clinical practice is a gradual, clinician-managed taper rather than stopping outright.

Opioids

Fentanyl, heroin, oxycodone, hydrocodone

Medical supervision advised

Withdrawal is severe — flu-like symptoms, vomiting, diarrhea, agitation. Complications including dehydration from persistent vomiting and diarrhea can become serious, and the rapid loss of tolerance afterward sharply raises overdose risk if use resumes. Medication for opioid use disorder changes the picture substantially.

Stimulants

Methamphetamine, cocaine, prescription amphetamines

Medical supervision advised

The comedown is largely psychological: exhaustion, heavy sleep, low mood, and strong craving. Depression, agitation, and suicidal thinking during this window are a genuine safety concern and a reason to have support in place.

Cannabis & nicotine

Marijuana, vapes, cigarettes

Lower physical risk

Irritability, disturbed sleep, appetite change, low mood, and craving. Physical complications are uncommon compared with alcohol or sedatives, but symptoms are frequently underestimated and can still warrant clinical support.

Withdrawal risk level by drug class, with what withdrawal typically involves
Drug class	Risk level	What withdrawal typically involves
AlcoholBeer, wine, spirits	Can be life-threatening	Tremor, sweating, and anxiety can progress to seizures and delirium tremens in people with heavy, sustained use. Guidance treats unmanaged alcohol withdrawal as a potential medical emergency. Stopping should be planned with a clinician.
Sedatives & benzodiazepinesXanax, Klonopin, Valium, Ativan	Can be life-threatening	Abrupt discontinuation after sustained use can produce seizures. Clinical practice is a gradual, clinician-managed taper rather than stopping outright.
OpioidsFentanyl, heroin, oxycodone, hydrocodone	Medical supervision advised	Withdrawal is severe — flu-like symptoms, vomiting, diarrhea, agitation. Complications including dehydration from persistent vomiting and diarrhea can become serious, and the rapid loss of tolerance afterward sharply raises overdose risk if use resumes. Medication for opioid use disorder changes the picture substantially.
StimulantsMethamphetamine, cocaine, prescription amphetamines	Medical supervision advised	The comedown is largely psychological: exhaustion, heavy sleep, low mood, and strong craving. Depression, agitation, and suicidal thinking during this window are a genuine safety concern and a reason to have support in place.
Cannabis & nicotineMarijuana, vapes, cigarettes	Lower physical risk	Irritability, disturbed sleep, appetite change, low mood, and craving. Physical complications are uncommon compared with alcohol or sedatives, but symptoms are frequently underestimated and can still warrant clinical support.

General reference only, not medical advice. Sources: StatPearls, Withdrawal Syndromes and Alcohol Withdrawal Syndrome; SAMHSA TIP 45, Detoxification and Substance Abuse Treatment. Anyone considering stopping alcohol or benzodiazepines after sustained heavy use should talk to a clinician first.

See withdrawal timelines by substance How medical detox works

How It Is Diagnosed

The 11 Signs Clinicians Actually Look For

Substance use disorder is diagnosed against 11 DSM-5 criteria. Meeting two or more in a 12-month period indicates a disorder — 2 to 3 is mild, 4 to 5 is moderate, 6 or more is severe. Tolerance and withdrawal alone do not count when a medication is being taken as prescribed under medical supervision.

Impaired control

Using more, or for longer, than intended
Wanting to cut down or stop, and not being able to
Spending a lot of time getting, using, or recovering from the substance
Craving the substance

Social impairment

Use interfering with work, school, or home responsibilities
Continuing to use despite it causing relationship problems
Giving up activities that used to matter

Risky use

Using in situations where it is physically hazardous
Continuing to use despite a physical or mental health problem it causes or worsens

Physical adaptation

Tolerance — needing more for the same effect
Withdrawal — symptoms when the substance leaves the body

Criteria as presented in SAMHSA's 2025 NSDUH Annual National Report (Table 1), drawn from the DSM-5. This page is informational and is not a diagnostic tool.

Treatment

What Treatment Exists Depends on the Substance

“Rehab” is not one thing. For some substances there are approved medications with decades of evidence behind them. For others, there is no approved medication at all, and the evidence sits entirely with behavioral treatment.

Sources: SAMHSA TIP 63, Medications for Opioid Use Disorder; NIDA, Treatment and Recovery.

Go Deeper

Common Questions

Frequently Asked Questions

Which drug withdrawals are actually dangerous?

Alcohol and sedative-hypnotics such as benzodiazepines are the withdrawal syndromes most associated with life-threatening complications, including seizures and delirium tremens, and clinical guidance treats them as requiring medical supervision. Opioid withdrawal is intensely uncomfortable and is not usually life-threatening on its own, though dehydration and the sharp loss of tolerance that follows create real risk. Stimulant and cannabis withdrawal are primarily psychological — low mood, fatigue, disturbed sleep, and craving.

How many people in the U.S. have a substance use disorder?

In 2025, an estimated 44.6 million people aged 12 or older — 15.3 percent of that population — met criteria for a substance use disorder in the past year, according to SAMHSA's National Survey on Drug Use and Health, released in July 2026. That included 25.7 million people with an alcohol use disorder and 26.0 million with a drug use disorder, with 7.1 million meeting criteria for both. Overall prevalence has fallen from 16.7 percent in 2021.

How is a substance use disorder actually diagnosed?

Clinicians use the 11 DSM-5 criteria, which cover impaired control, social impairment, risky use, and physical adaptation such as tolerance and withdrawal. Meeting two or more criteria within a 12-month period indicates a disorder: 2 to 3 criteria is mild, 4 to 5 is moderate, and 6 or more is severe. Tolerance and withdrawal alone do not indicate a disorder when a medication is being taken as prescribed under medical supervision.

Is there medication for every substance?

No. There are FDA-approved medications for opioid use disorder (buprenorphine, methadone, and naltrexone), alcohol use disorder (naltrexone, acamprosate, and disulfiram), and nicotine dependence. There is no FDA-approved medication for stimulant use disorder such as methamphetamine or cocaine, or for cannabis use disorder — treatment for those relies on behavioral approaches such as contingency management and cognitive behavioral therapy.

What is driving overdose deaths right now?

Synthetic opioids other than methadone — a category dominated by illicitly manufactured fentanyl — are involved in more U.S. overdose deaths than any other drug category in CDC's provisional counts, followed by psychostimulants such as methamphetamine and by cocaine. Because most overdose deaths involve more than one drug, a single death is counted in each category it involves.

Does needing detox mean needing residential rehab?

Not automatically. Detox stabilizes the body; it is not treatment for the underlying disorder. Some people step from detox into residential care, others into a partial hospitalization or intensive outpatient program, and others into standard outpatient care with medication. The right level depends on withdrawal risk, medical and psychiatric conditions, and how stable the person's living situation is.

Article references

01SAMHSA (Substance Abuse and Mental Health Services Administration). Key Substance Use and Mental Health Indicators in the United States: Results from the 2025 National Survey on Drug Use and Health. View source
02CDC / National Center for Health Statistics. VSRR Provisional Drug Overdose Death Counts. View source
03StatPearls / NCBI Bookshelf. Withdrawal Syndromes. View source
04StatPearls / NCBI Bookshelf. Alcohol Withdrawal Syndrome. View source
05SAMHSA (Substance Abuse and Mental Health Services Administration). Medications for Opioid Use Disorder (TIP 63). View source
06SAMHSA (Substance Abuse and Mental Health Services Administration). Detoxification and Substance Abuse Treatment (TIP 45). View source
07NIDA (National Institute on Drug Abuse). Treatment and Recovery (Research Topics). View source

Clinical Review

Who Reviews These Guides

Medically reviewed by Cole Timonere, PhD, JD, LMHC, LPCC

Medical Reviewer for Treatment Locators

Medically reviewed by Ailyn Corchado, LMSW, LCDC

Medical Reviewer for Treatment Locators

In Development

Each new guide is written and clinically reviewed the same way, then published with its sources listed on the page.

Coming soonHeroinOpioids
Coming soonOxycodone & Prescription PainkillersOpioids
Coming soonXanax (Alprazolam)Depressants
Coming soonAdderall & Prescription StimulantsStimulants
Coming soonKratom & 7-OHCannabis & Nicotine
Coming soonHallucinogens & KetamineCannabis & Nicotine

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