This is defined as an uncontrollable desire to scratch the anus. It is a symptom and NOT a diagnosis.

Epidemiology

It is present in approximately 5% of the population and is four times more common in men than women.¹
It can occur at any time of life but is more common between 40-70 years of age.
It is most commonly experienced after a bowel motion or at night. The itch may be worsened by wool, heat, moisture, leaking and stress.²

Assessment

• Take a thorough history to include potential irritant factors such as powders, creams and soaps. There may be problems keeping the area dry.
• Note duration and pattern of itch; does it occur mainly at night, e.g. threadworms or are all the family affected, e.g. scabies.
• Dietary factors e.g. tomatoes, citrus fruit, spicy foods may be implicated.
• Appearance varies according to severity and chronicity. The anal ring may eventually appear shiny.
• Exclude secondary causes - infections, fistula, fissure, dermatological conditions, systemic disease, e.g. diabetes, lymphoma, renal failure, anaemia or hyperthyroidism.³ Topical treatments and systemic medications, e.g. colchicine or peppermint oil.

Management

• Avoidance of irritants and good personal hygiene are the mainstays of treatment.
• Symptomatic treatment may help alleviate symptoms whilst these measures are put in place.
• Dietary modification may be useful if implicated in causation.
• Excessive moisture around the anus can contribute to the problem, particularly if obese and/or hairy. A hair dryer may be useful for thoroughly drying the area after washing. A cotton tissue placed in the underwear may help absorb extra moisture throughout the day. Cotton underwear should be used in preference to synthetics.

Referral to colorectal surgeon or dermatologist should be considered in any patient who has had no relief after 3-4 weeks of conservative measures.

Available therapies

• Bland, protective, soothing ointments are first-line treatment.
• A short course of a mildly potent corticosteroid may be used. Long-term use is to be avoided as it may cause dermatitis and exacerbate the itch.
• There is no evidence that anti-histamines will help the underlying condition, but a short course may alleviate symptoms that are disturbing sleep.
• Avoid using local anaesthetics, systemic steroids, capsaicin⁴ or hypnosis.⁵

Complications

Persistent scratching may lead to dermatitis, excoriation and infection. Depression may follow severe, persistent symptoms.

Prognosis

Unless a cause is found it may become a chronic complaint.
Most people respond well to simple measures, but may have periodic relapse.

Document references

1. Pruritus Ani, Clinical Knowledge Summaries (2008)
2. Chaudhry, V and Bastawrous A.( 2003) Idiopathic pruritus ani. Seminars in Colon and Rectal Surgery 14(4),196-202.
3. Hanno R, Murphy P; Pruritus ani. Classification and management.; Dermatol Clin. 1987 Oct;5(4):811-6. [abstract]
4. Lysy J, Sistiery-Ittah M, Israelit Y, et al; Topical capsaicin--a novel and effective treatment for idiopathic intractable pruritus ani: a randomised, placebo controlled, crossover study.; Gut. 2003 Sep;52(9):1323-6. [abstract]
5. Rucklidge JJ, Saunders D; Hypnosis in a case of long-standing idiopathic itch.; Psychosom Med. 1999 May-Jun;61(3):355-8. [abstract]

Acknowledgements