The Toilet Paper

How long does it take for a child to pass a Lego figurine head?

This is a summary of a paper that poses a simple question and uses a simple method to find a simple answer.

Everything about this paper is awesome

Young children are in a developmental stage during which they’re still learning to explore their environment and may ingest objects that offer no nutritional value. Coins are seemingly the most ingested item, as most scientific studies focus on ingestion of coins.

Previous research suggests that most coins pass within three to six days with no adverse effects. How long does it take for a Lego head to pass through a human body?



The authors recruited six adult participants (themselves) for an experiment that involved the ingestion of a Lego head.

Prior to the experiment, each participant kept a 3-day stool diary that allowed for the calculation of a Stool Hardness and Transit (SHAT) score. A high score indicates more frequent, loose bowel movements, while a low score indicates less frequent or firmer movements.

The actual ingestion took place at roughly the same time of day to minimise daily variations in bowel habits. Participants then examined their own stools over the next few days until they found the Lego head. The transit time is used to calculate a Found and Retrieved Time (FART) score.



were able to locate the Lego head in their stools.

FART scores ranged from 1.14 days (27h20m) to 3.04 days (72h35m). The female participants managed to retrieve the Lego head within two bowel motions, while the two male participants only retrieved it on their third bowel motion.

Ingestion of Lego heads did not appear to have a significant impact on the SHAT scores, i.e. the consistency of bowel motions in participants.

The authors therefore conclude that small objects, such as those swallowed by children, are likely to pass within 1–3 days without any complications. This is good news for parents!



This study has some rather apparent limitations, which were pointed out in a letter to the editor. The authors of this letter propose a randomised, longitudinal Placebo or Object Passing (POOP) study that addresses some of these limitations. The design of that POOP study is depicted in the diagram below.

Design of the POOP trial that’s laid out like a Lego head

Design of the proposed POOP trial


  1. If your child swallows a small object, it will likely pass in 1–3 days with no complications