How addiction works.

The loop behind every addiction

Whatever the substance or behaviour, the same four-step loop shows up. Step through it.

The brain's reward system runs on dopamine, which is less a pleasure chemical than a "do that again" signal. Natural rewards like food, sex and friendship raise it a little. Addictive drugs and designs raise it much more, much faster, or in unpredictable bursts, and the brain responds by turning down its own sensitivity. That is tolerance. The result is a system that needs the hit just to feel normal, which is a very different thing from wanting a good time.

Explore each one

Eleven profiles, all built the same way: what it is, what it does in the brain and body, the good, the bad, why it hooks, what makes it dangerous, withdrawal, and where to turn.

Compare two side by side

The comparison is a rough guide, not a lab measurement. Dose, method, age, genetics and mental health change everything, and a low rating never means safe.

Honest self-check

Eleven questions, based on the criteria doctors actually use for substance use disorder. It is not a diagnosis, nothing is saved or sent anywhere, and you can close the page and it's gone. Tick what has been true for you over the past year.

If you take a medicine exactly as prescribed, needing more and feeling withdrawal can happen without addiction, so don't count those two on their own.

Ask a question

Type a question or a word like "withdrawal", "fentanyl", "vaping" or "Xanax". These answers are pre-written, so you'll get matching ones from the library below, not a live chatbot. What you type stays on your device.

Myths worth dropping