oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
This is defined as an uncontrollable desire to scratch the anus. It is a symptom and NOT a diagnosis.
- It is present in approximately 5% of the population and is four times more common in men than in women.
- It can occur at any time of life but is more common between 40-60 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.
- 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 - whether it occurs mainly at night, eg threadworms, or all family members are affected, eg scabies.
- Dietary factors, eg tomatoes, citrus fruit, spicy foods, coffee, colas, chocolate, tea, and beer, have all been identified as aggravating factors.
- Appearance varies according to severity and chronicity. The anal ring may eventually appear shiny.
- Exclude secondary conditions (see 'Causes', below), topical treatments and systemic medications, eg colchicine or peppermint oil.
- The majority of pruritus ani is idiopathic and is termed primary pruritus ani.
- Secondary causes can include:
- Infections: fungal, parasitic (pinworms or scabies) or viral (condyloma secondary to human papillomavirus).
- Fistulas, haemorrhoids, faecal incontinence.
- Skin disorders such as contact dermatitis, atopy, lichen sclerosus, seborrheic dermatitis, atopic dermatitis.
- Anal carcinoma, Bowen's or extramammary Paget's disease.
- Systemic disease, eg diabetes, lymphoma, renal failure, iron-deficiency anaemia, hyperthyroidism.
- Treat secondary causes.
- Avoidance of irritants (egscented soaps, talcum powder, bubble bath, perfume, etc.) around the anus.and good personal hygiene are the mainstays of treatment of primary pruritus ani.
- Symptomatic treatment may help to 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 the patient is obese and/or hairy. A hairdryer may be useful for thoroughly drying the area after washing. A cotton tissue placed in the underwear may help to absorb extra moisture throughout the day. Cotton underwear should be used in preference to synthetics.
Referral to a colorectal surgeon or dermatologist should be considered in any patient who has had no relief after 3-4 weeks of conservative measures.
- Bland, protective, soothing ointments are first-line treatment (eg bismuth subgallate, zinc oxide).
- 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 antihistamines will help the underlying condition; however, a short course of a sedative antihistamine such as chlorpheniramine may alleviate symptoms that are disturbing sleep.
- There is some evidence that intractable cases may respond to capsaicin or injection of methylthioninium chloride (methylene blue) with or without local anaesthetic and a steroid, intracutaneously and subcutaneously.
Persistent scratching may lead to dermatitis, excoriation and infection. Depression may follow severe, persistent symptoms.
Unless a cause is found it may become a chronic complaint. Most people respond well to simple measures, but may have periodic relapse.
Further reading & references
- Pruritus ani, DermNet NZ, 2012
- Song SG, Kim SH; Pruritus ani. J Korean Soc Coloproctol. 2011 Apr;27(2):54-7. Epub 2011 Apr 30.
- Siddiqi S, Vijay V, Ward M, et al; Pruritus ani. Ann R Coll Surg Engl. 2008 Sep;90(6):457-63.
- Pruritus ani, Prodigy (August 2008)
- Davis B; Pruritus Ani, Pilonidal Sinus and Hidradenitis Suppurativa, American Society of Colon and Rectal Surgeons, 2012.
- Samalavicius NE, Poskus T, Gupta RK, et al; Long-term results of single intradermal 1 % methylene blue injection for Tech Coloproctol. 2012 Jun 6.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Hayley Willacy
Dr Laurence Knott
Prof Cathy Jackson