[8] The Bristol stool scale is also very sensitive to changes in intestinal transit time caused by medications, such as antidiarrhoeal loperamide, senna, or anthraquinone with laxative effect.

[23] Historically, this scale of assessment of the faeces has been recommended by the consensus group of Kaiser Permanente Medical Care Program (San Diego, California, US) for the collection of data on functional bowel disease (FBD).

Moreover, the nature of the stool is affected by age, sex, body mass index, whether or not they had cholecystectomy and possible psychosomatic components (somatisation); there were no effects from factors such as smoking, alcohol, the level of education, a history of appendectomy or familiarity with gastrointestinal diseases, civil state, or the use of oral contraceptives.

Several investigations correlate the Bristol stool scale in response to medications or therapies, in fact, in one study was also used to titrate the dose more finely than one drug (colestyramine) in subjects with diarrhoea and faecal incontinence.

[42] Developed and proposed for the first time in England by Stephen Lewis and Ken Heaton at the University Department of Medicine, Bristol Royal Infirmary, it was suggested by the authors as a clinical assessment tool in 1997 in the Scandinavian Journal of Gastroenterology[14] after a previous prospective study, conducted in 1992 on a sample of the population (838 men and 1,059 women), had shown an unexpected prevalence of defecation disorders related to the shape and type of stool.

That conclusion has since been challenged as having limited validity for Types 1 and 2;[44] however, it remains in use as a research tool to evaluate the effectiveness of treatments for various diseases of the bowel, as well as a clinical communication aid.