Understanding Addiction in Plain English: Why Can't They Just Stop?

It’s easy to read that broken promise as lying or not caring. Knowing what’s going on underneath can get you out of the argument about willpower and onto a more useful question: how to get them to someone who can help.

What is a substance use disorder?

It’s a pattern of alcohol or drug use that keeps causing problems and that the person struggles to control. NIAAA describes alcohol use disorder as an impaired ability to stop or control drinking despite harm to health, work or relationships.¹ Clinicians diagnose it using DSM-5 criteria. For alcohol there are 11, and the number someone meets sets the severity: mild (2–3), moderate (4–5) or severe (6 or more).¹³ Drug use disorders also range from mild to severe.²

You don’t need to diagnose anyone. For what to watch for at home, see what families tend to notice first.

Why can’t they just stop?

Mostly because of those brain changes. SAMHSA notes they make quitting hard even for people who truly want to stop,⁴ and heavy drinking affects the parts of the brain that handle decision-making and impulse control.⁵

The body gets involved too. When someone is physically dependent, stopping or cutting back quickly makes them sick,⁷ and over time using can become more about relieving that misery than chasing a high.⁵ Add cravings, urges strong enough to crowd out other thoughts,¹ and it makes sense that guilt, threats and promises so rarely work on their own.

Some people recover without treatment, especially when the problem is milder,⁶ but that gets harder as it progresses.⁵

Is addiction a disease or a choice?

Most people choose to try a substance. Addiction is what happens when that choice gets harder and harder to make freely. SAMHSA and NIAAA both treat it as a brain disease rather than a failure of willpower or morals.⁴¹

In our view that doesn’t excuse anything; they’re still responsible for their choices, including getting help. But it points to what works: a plan, medication where it fits, check-ins, and adjustments when things slip, as with any long-term illness.

NIAAA also suggests saying “a person with alcohol use disorder” instead of “alcoholic,” because labels can imply the person is entirely to blame.⁸

What’s the difference between dependence, tolerance and addiction?

Tolerance and dependence are the body adapting to a substance. Addiction is compulsive use despite harm. Someone can have one without the other.

Dependence can happen even with a medicine taken exactly as prescribed. The FDA lists it as a separate risk from addiction, and someone taking a benzodiazepine steadily can become dependent within days to weeks.⁷

So a father who has taken a prescribed sedative exactly as directed for years, and gets shaky when he misses a dose, is dependent. He needs his doctor’s help to taper. A brother with a DUI who hides bottles and promises every Monday to cut back has the lost control clinicians call a substance use disorder. He needs an assessment.

Anyone dependent on alcohol or a sedative should get medical advice before quitting, because stopping suddenly can cause seizures; here’s why that matters.⁷⁹

What are cravings, and can they be managed?

Cravings, along with low moods and poor sleep, can linger long after someone stops,⁶ which is one reason relapse can happen even after a long stretch without using.¹ They can be treated. In cognitive-behavioral therapy, people learn to spot the situations and stresses that trigger urges and practice ways to cope.¹¹ FDA-approved medications for alcohol and opioid use disorders can ease withdrawal and cravings, and SAMHSA is clear that buprenorphine and methadone are evidence-based treatments, not one drug swapped for another.¹² More on how medications for addiction work.

Why do some people develop addiction and others don’t?

There’s no single cause. For alcohol, NIAAA points to drinking at an early age, genetics and family history, mental health conditions and past trauma, along with how much, how often and how fast someone drinks.¹ None of these makes addiction certain.

Mental health conditions and substance use disorders often show up together, and both need treatment.¹⁰

Can someone recover from addiction?

Yes. In SAMHSA’s 2025 national survey, 73.0% of adults who said they’d ever had a problem with drugs or alcohol considered themselves recovered or in recovery.²

Recovery tends to work like managing other chronic illnesses. The VA describes it as ongoing and recommends continued care,¹⁰ and NIAAA notes that returns to heavy drinking are common but tend to become less frequent over time.⁶ A return to use means the plan needs adjusting. Here’s what to do if a relapse happens.

How can families use this?

Name what you’ve seen and what worries you, and ask them to see a doctor just to get information. If talks keep turning into fights, CRAFT teaches families to encourage treatment without a showdown. Let a professional assessment decide the level of care, and find some support for yourself along the way.

When you’re ready, start with how to open the first conversation. Our guide to getting help shows the whole path.