Anal itching
BMJ 2016; 355 doi: https://doi.org/10.1136/bmj.i4931 (Published 04 November 2016) Cite this as: BMJ 2016;355:i4931- Kapil Sahnan, colorectal surgical registrar12,
- Laurence Lever, consultant dermatologist3,
- Robin K S Philips, consultant surgeon12
- 1Imperial College Faculty of Medicine, London, UK
- 2St Mark’s Hospital, London
- 3Department of Dermatology, Northwick Park Hospital, London, UK
- Correspondence to: K Sahnan ks303{at}doctors.org.uk
- Accepted 13 July 2016
What you need to know
Ask about frequent stools and leaking because faeces are a known irritant of the perianal skin
A symptom diary can help to identify foods, allergens, or washing practices associated with symptoms, but most commonly no cause is found
Avoid triggers and consider a short course of topical steroids for acute pruritis
A 39 year old lorry driver describes three months of an itchy bottom. He has tried to improve his hygiene and showers several times a day. It has now become embarrassing in public. He is otherwise well, his bowel habit is unchanged, and he has had no rectal bleeding and no history of bowel problems.
Itching in the perianal area—pruritus ani—causes discomfort with an uncontrollable desire to scratch. Patients may be embarrassed to talk about it. Data on prevalence and aetiology are scarce because most patients do not consult a doctor.1 It is estimated that 5% of the population are affected by anal itching at some point in life, more commonly men, and predominantly when they are in the fourth to sixth decade of life.2 Itching may be short lived or chronic and can be caused by local factors or systemic disease (box 1). More commonly, it is idiopathic and no cause is identified.3 4
Box 1: Possible causes of pruritus ani (idiopathic if no cause is identified)
Colorectal
Chronic diarrhoea, chronic constipation, haemorrhoids (fig 1⇓), fissures, fistulas, colorectal and anal cancers (including anal intraepithelial neoplasia), …
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