Alli (orlistat 60 mg) leaves your system quickly. The half-life of absorbed orlistat is only 1 to 2 hours, and less than 1% of each dose ever reaches your bloodstream in the first place. Within roughly 24 to 48 hours of your last dose, the drug and its effects are essentially gone.
How Alli Works in Your Body
Unlike most medications, Alli barely enters your bloodstream at all. It works almost entirely inside your digestive tract, where it blocks roughly 25% of the fat you eat from being absorbed. The drug attaches to fat-digesting enzymes in your stomach and small intestine, disabling them so that undigested fat passes through your body in your stool.
Because Alli stays in the gut rather than circulating through your blood, the concept of it “staying in your system” is a bit different from other drugs. There are really two timelines to consider: how long the tiny absorbed portion lingers in your blood, and how long the drug remains active in your digestive tract.
How Long Alli Stays in Your Blood
Almost none of it gets there. Orlistat has an oral bioavailability below 1%, meaning that out of a 60 mg dose, a negligible amount makes it past your gut wall. Plasma concentrations are so low that they’re often undetectable in lab tests, falling below 5 ng/mL within 8 hours of taking even a dose six times higher than the standard Alli capsule. The small amount that is absorbed has a half-life of 1 to 2 hours, so it clears from your blood rapidly.
There is also no evidence of accumulation. Even people taking orlistat regularly over weeks or months don’t build up meaningful levels in their blood. Each dose is processed and cleared independently.
How Long Alli Stays in Your Digestive Tract
This is where the drug actually does its work, and where almost all of it ends up. About 97% of each dose is eliminated through stool. Roughly 83% leaves your body as unchanged orlistat, meaning it passes through without being broken down at all. A small additional portion is converted into two inactive byproducts that are also excreted in stool. Only about 1 to 4% of the dose leaves through urine.
The transit time through your digestive system depends on your individual digestion speed, but most people clear a dose within 24 to 48 hours. This aligns with normal gut transit time. Once the orlistat in your intestine moves through with your next few bowel movements, it’s gone.
When the Fat-Blocking Effect Stops
Alli’s fat-blocking action is tied directly to the drug being present in your gut alongside a meal. Each dose works on the meal you take it with (and for a few hours afterward as that meal is digested). Once the drug clears your digestive tract, your fat-digesting enzymes return to full function.
This is why Alli is taken three times a day with meals. It doesn’t create a lasting effect between doses. If you skip a dose or eat a fat-free meal, there’s nothing for the drug to act on. After your final dose, the fat-blocking effect wears off as soon as that last bit of orlistat passes through your intestines, typically within a day or two.
Why People Ask This Question
If you’re stopping Alli and wondering when it’s fully out of your system, the practical answer is 1 to 2 days. You can expect the digestive side effects (oily stools, increased bowel movements, gas) to resolve within that same window once you stop taking it. Your body doesn’t need to “detox” from the drug because so little of it was ever absorbed.
If you’re asking because of a drug interaction concern, the more relevant issue is that Alli can reduce absorption of fat-soluble vitamins (A, D, E, and K) and certain medications while you’re actively taking it. That effect is also limited to the window when the drug is present in your gut. Once you’ve stopped and had a couple of normal bowel movements, absorption returns to normal.
For anyone concerned about a drug test, orlistat is not a controlled substance and is not screened for in standard drug panels. Its near-zero blood levels and rapid clearance make it essentially invisible in blood or urine testing even while you’re actively taking it.