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Will chewing gum knot up your insides?


Amelia, aged ten and three-quarters, comes to you asking if she can have some chewing gum.

Staring wistfully back through the years, you remember your mother’s words. “Don’t swallow it. It’ll will knot you up.”

As someone who knows a thing or two about swallowing things that they should not, I have been pondering my mother’s advice.

A brief history of gum

People have been chewing things since they had teeth. Archaeologists digging in Finland have found fossilized pieces of birch bark tar from 5000 years ago that suggest our most ancient ancestors indulged. Despite its age, scientists could sequence the DNA of our nomadic ancestor from the ‘gum’.

Step forward a few millennia, and the Mayans could be found slicing off resin from the Sapodilla tree and using it to stick tools together. This chicle was also chewed to stave off thirst.

Meanwhile, over in the Old World, Herodotus was describing the mastic tears of Chios. It was said that when the Romans slaughtered St Isadore in the grove of Mastic (Pistacia lentiscus) that grew on the small Greek island, the trees wept clear tears at what they had witnessed. These clear drops of resin were chewed to aid digestion and bad breath and improve one’s well-being. We get the word to masticate – to chew – from these trees.

Chewing gum as we know it didn’t come into vogue until the mid-19th century. North American Indians chewed the sap of the Spruce trees, and in another case of cultural appropriation, John B. Curtis developed The State of Maine Pure Spruce Gum.

Some ten years later, Mexico’s former president, General Antonio Lopez de Santa Anna, brought chicle to New York in the hope that it could be sold as a rubber substitute and bolster trade between the US and Mexico. It failed as a rubber substitute, but Thomas Adams cut it into strips and flavoured it. Around this time, Black Jacks, Chiclets and Wrigley’s Spearmint gum came into being. Gum grew in popularity and, by the mid-20th century was traded away as part of a GI’s ration pack for local favours.

Perhaps, that gum you like is coming back in style?

What is in chewing gum?

Constituents of the average stick of sugar-free gum

By 1999, we ate 560,000 tonnes a year or 374 billion pieces. If you laid those end-to-end, they would stretch approximately 27.5 million kilometres (the diameter of the gas giant formally known as a planet, Pluto).

Is it good for you?

Cows spend their lives chewing the cud, and you don’t regularly see thin cows. To find out just how much energy chewing burns, Levine et al. performed an experiment that would make fans of DFTB proud. They got eight healthy volunteers to chew 8.4g of sugar-free gum for 12 minutes and then indirectly measured their calorie expenditure. To ensure that nobody chewed more than any other, they had them eat to the beat of a metronome tick-tocking at 100hz.

Chewing gum raises your basal calorie expenditure by around 11 calories. In context, you burn around 11 more calories standing rather than sitting and would burn just over 100 calories if you walked at the extremely tedious pace of 1 kmph.

Gum use has also been linked with increased concentration, and there is evidence that chewing sugar-free gum reduces your chance of getting dental caries.

So, does it knot up your insides?

The body treats most gum like any other indigestible matter – it passes through without effect approximately two days (depending on the previous Stool Hardness And Transit score). But this non-nutritive masticatory substance (it’s not food) may cause one or two problems.

What is a bezoar?

A bezoar (from the Arabic bazahr, and Persian padzehr meaning antidote) is a concretion of foreign material. They were long thought to be a cure for poisoning hence this scene in Harry Potter and the Half-Blood Prince when our lightning-scarred hero thrusts a bezoar into Ron’s mouth after he has accidentally taken in the spiked Chocolate Cauldrons from Romilda Vane. Only in 1779 did physicians realise that bezoars were the product of illness, not the cure.

Bring out the bezoar!

Bezoars may be formed from plants (phytobezoar), medications (pharmacobezoar), milk proteins (lactobezoar) and even hair. You can read more about Rapunzel Syndrome – trichobezoar formation in the setting of trichotillomania in an earlier post). Bezoars can also form from other partially digestible or indigestible items such as paper and chewing gum. The majority will grow in the stomach, but some make it much further down the GI tract.

Adapted from Magee, J.S. and Bernick, S.J., 2020. Undigested Gum Found During Colonoscopy. ACG Case Reports Journal7(3)

Paediatric gastroenterologist, David Milov, described three case reports of undigested gum fecoma. He writes of the telltale ‘taffy-pull’ pull sign as the gum was endoscopically extruded from the firm mass into a fine fluffy tail. Otherwise, you could do what Neuberger et al. did and use your nose. They described the 5 x 5cm oesophageal mass they encountered as having ‘a minty aroma’.

Adapted from Sinopidis, X., Zachos, K., Panagidis, A., Alexopoulos, V., Vareli, A. and Georgiou, G., 2021. Chewing gum bezoar as an unexpected cause of acute intestinal obstruction. Journal of Paediatrics and Child Health57(9), pp.1533-1535.

These gummy globs will not go away on their own, and Nanton et al. reported a case of a 15-year-old girl who admitted to having had a phase of chewing and swallowing gum and hair three years before her presentation with abdominal pain and bilious vomiting.

It’s not just the chewy bit that may cause harm. Excluding medicated gums (such as nicotine replacement gums)l, it is not just the chewy bit that leads to misadventure.

And as we all know, unlicensed use of gum can lead to generalized cyanosis, oedema and weight gain, as evidenced by Dahl (1964)

Selected references

Amirlak, I., Hardy, J.D., Anjikar, C. and Khaled, N.S., 2018. Pyloric Obstruction in a Child- An an uncommon cause. ARC Journal of Radiology and Medical Imaging. 2018; 3 (1): 1213.

Aveling, E., 1997. Chew, chew, that ancient chewing gum. British Archaeology (York), (21).

Baudamant M. “Description of two masses of hair found in the stomach and intestines of a young boy aged sixteen.” Hist Soc Roy Med , Paris. 1777–1779;2:262–63.

Cotner, M., 1982. Fecal impaction due to bubble gum bezoar. Southern medical journal75(6), p.775.

Dahl, R 1964, “Charlie and the Chocolate Factory”, OCLC 9318922 (hardcover, Alfred A. Knopf, Inc., original, first US edition, illustrated by Joseph Schindelman)

Dörterler, M.E., Günendi, T., Çakmak, M. and Shermatova, S., 2020. Bezoar types in children and etiological factors affecting bezoar formation.

Goldberg, L.D. and Ditchek, N.T., 1978. Chewing gum diarrhea. The American journal of digestive diseases23(6), pp.568-568.

Imfeld T. Chewing gum–facts and fiction: a review of gum-chewing and oral health. Crit Rev Oral Biol Med. 1999;10(3):405-19. doi: 10.1177/10454411990100030901. PMID: 10759416.

Levine, J., Baukol, P. and Pavlidis, I., 1999. The energy expended in chewing gum. New England Journal of Medicine341(27), pp.2100-2100.

Magee, J.S. and Bernick, S.J., 2020. Undigested Gum Found During Colonoscopy. ACG Case Reports Journal7(3)

Matson, J., 2007. Fact or Fiction?: Chewing Gum Takes Seven Years to Digest. Scientific American Global RSS. Scientific American11.

Milov, D.E., Andres, J.M., Erhart, N.A. and Bailey, D.J., 1998. Chewing gum bezoars of the gastrointestinal tract. Pediatrics102(2), pp.e22-e22.

Morgan, K., Johnson, A.J. and Miles, C., 2014. Chewing gum moderates the vigilance decrement. British Journal of Psychology, 105(2), pp.214-225.

Nanton, S., Roskens, J. and Feit, S., 2015. Bizarre Bezoar: An Unusual Cause of Abdominal Pain and Vomiting in a Pediatric Patient: 935. Official journal of the American College of Gastroenterology| ACG110, p.S400.

Neuberger, F., Collins, J. and Patel, S., 2014. A sticky situation. Emergency Medicine Journal31(7), pp.592-592.

Rimar, Y., Babich, J.P. and Shaoul, R., 2004. Chewing gum bezoar. Gastrointestinal endoscopy59(7), p.872.

Sinopidis, X., Zachos, K., Panagidis, A., Alexopoulos, V., Vareli, A. and Georgiou, G., 2021. Chewing gum bezoar as an unexpected cause of acute intestinal obstruction. Journal of Paediatrics and Child Health57(9), pp.1533-1535.

Truex, J.H., Silberman, T.L. and Wood, B.P., 1989. Radiological case of the month. Bubble gum bezoar. American journal of diseases of children (1960)143(2), pp.253-254.

Yildiz, T. and Ateş, D.Ç., Recurrent Gastric Gummy Bezoar: A Case Report. Journal of Emergency Medicine Case Reports1(1), pp.15-17.




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