Itchy anus

What is itchy anus?

Itchy anus is a common complaint described as an intense itch in the perianal area between the buttocks. Perianal itch can be the result of an infestation, skin infection, inflammatory skin condition, and, rarely, a skin tumour. When there is no obvious cause for the itch it is called pruritus ani.

Who gets itchy anus?

Itchy anus is common, affecting up to 5% of individuals at some time in their life. Men are more commonly affected than women, with a male to female ratio of 4:1. Although all age groups can be affected, the fourth to sixth decade is the most common time to develop an itchy anus.

What causes itchy anus?

Itchy anus can be classified as being primary (idiopathic, no obvious cause) or secondary.

Pruritus ani

Primary perianal itch is more common than secondary.

Factors contributing to an itchy anus may include:

• Perianal hypertrichosis
• Perianal hyperhidrosis
• Deeply set anal opening (so-called funnel-shaped anus)
• Irritating stools particularly if there is diarrhoea or faecal leakage, and if acidic or highly spiced foods are eaten
• Overzealous cleaning and use of personal care products
• Systemic disease — diabetes mellitus, uraemic pruritus, liver disease, thyroid disease, haematological disorders.

Secondary perianal itch

Any common skin disease may involve the anogenital area resulting in secondary anal itching, and this may be the only site of involvement. Anal itch is unrelated to haemorrhoids or other anal conditions.

• Skin infections
  • Bacterial — perianal streptococcal dermatitis, erythrasma
  • Fungal — Candidal intertrigo, dermatophyte such as Trichophyton rubrum
  • Viral — anogenital warts
• Infestations
  • Pinworms
• Inflammatory skin conditions [see Perianal dermatoses]
  • Dermatitis — atopic, seborrhoeic, contact (irritant or allergic)
  • Flexural psoriasis
  • Lichen sclerosus
  • Lichen planus
• Skin tumours
  • Anal squamous cell carcinoma
  • Extramammary Paget disease of the skin

Skin conditions that may present as an itchy anus

Lichen sclerosus 

Flexural psoriasis 

Extramammary Paget disease 

What are the clinical features of itchy anus?

Itchy anus is a symptom not a diagnosis, so a careful history and skin examination is required to reach a diagnosis.

• History
  • Onset and duration of symptoms — acute or chronic
  • Bowel habit — frequency, consistency
  • Cleaning routine — wet wipes, soap and cleansers, toilet paper
  • Over-the-counter and prescribed medications
  • Time of day itch occurs
  • Medical history including skin conditions
• Examination
  • Anogenital skin
  • Entire skin surface including scalp, flexures, and nails

See image pages — Perianal lichen sclerosus, Genital psoriasis, Extramammary Paget disease, Anal cancer

What are the complications of itchy anus?

• Lichen simplex
• Contact dermatitis due to products used to treat the perianal itch
• Secondary infection of the skin

How is itchy anus diagnosed?

Pruritus ani is diagnosed on a normal examination of perianal skin apart from possible secondary excoriations and lichenification.

The cause of secondary itchy anus is usually established on history and examination.

Investigations may be required to confirm the cause.

• Skin swab for bacteriology
• Skin scraping for mycology
• ‘Sticky tape’ test for pinworm ova
• Patch testing for allergic contact dermatitis
• Skin biopsy for inflammatory disorders or skin cancer

What is the differential diagnosis for itchy anus?

• Psychogenic pruritus
• Compulsive skin picking

What is the treatment for itchy anus?

General measures

• Cleanse regularly but gently using plain water. The perianal area may be cleaned using a bidet or showerhead after defecation or faecal leakage.
• Avoid abrasive or fragranced toilet tissue. Use cotton wool dipped in water or unscented wet wipes without allergenic preservatives such as methylisothiazolinone.
• Pat the perianal skin dry rather than rubbing with a towel.
• Do not use talc which cakes and worsens the itch.
• Cool compresses.
• Try not to scratch, keep fingernails short, and wear cotton gloves at night to minimise damage from scratching.
• Wear loose cotton underwear — avoid G-strings, panty liners, pantyhose.
• Avoid soaps and detergents — a light emollient such as aqueous cream can be used instead of soap.
• Increase dietary fibre to treat constipation or hard stools.
• Avoid heavily spiced foods. Excessive tea, coffee, cola, alcohol, chocolate, tomatoes, citrus fruits, grapes, prunes, and figs may exacerbate perianal itch.

Specific measures

• Treat the specific underlying condition
• Avoid contact with potential topical allergens
• Topical treatments for itch
  • Bland emollient or barrier cream such as white soft paraffin or zinc oxide cream
  • Short term low potency topical steroid
  • Local anaesthetic spray or ointment such as lignocaine (lidocaine)
• Systemic and other treatments for itch
  • Sedating antihistamines at night
  • Tricyclic antidepressants
  • Local methylene blue intradermal injections (anal tattooing)

What is the outcome for itchy anus?

Perianal itch usually improves with attention to the above. It may relapse during periods of stress, flare of the associated dermatosis, or if the above measures are relaxed.