Codeine is one of the mildest commonly prescribed opioids, but it still produces real physical dependence and withdrawal with regular use.
A quirk worth knowing: Codeine itself is a “prodrug” — the body converts it into morphine to produce its effect, via a liver enzyme (CYP2D6) that varies significantly between individuals. Some people convert codeine unusually quickly or slowly, which affects both how much relief they get from it and how withdrawal presents.
Rough timeline: Generally similar to other short-acting opioids — onset within 8–12 hours, peak around 1–3 days, acute resolution by about a week.
A common source of underestimated dependence: Because codeine is often viewed as “not a real opioid” (including in some cough syrups and combination products), physical dependence can develop without the person realizing they were taking an opioid regularly — worth naming directly if this applies to your situation.
Medically reviewed by [pending]. Source: SAMHSA TIP 63.