Pruritus Ani



  • Intense anal/perianal itching and/or burning
  • Usually acute (defined as <6 weeks of symptoms)
  • Classified as primary (idiopathic) or secondary (25–75% of cases) to anorectal pathology



  • 1–5% of the general population
  • Predominant age: 30 to 50 years; although seen in all age groups
  • Predominant sex: male > female (4:1)

Difficult to estimate because many patients do not report symptoms; affects 1–5% of the population

Etiology and Pathophysiology

  • Multiple etiologies categorized by inflammatory, infectious, systemic, neoplastic, anorectal disorders, neuropathic, neurogenic, and psychogenic causes (1),(2)
  • Most cases are idiopathic (25–90%), which are likely due to trauma from wiping or scratching and perianal fecal contamination.
    • Soilage can be due to an abnormality of rectoanal inhibitory reflex and a lower threshold or transient internal anal sphincter relaxation.
  • Depending on underlying etiology, itch pathway may be histamine mediated or nonhistamine mediated (1).
  • Pruritus ani is typically intensely perceived by the patient due to dense innervation.
  • Etiologies of secondary pruritus ani:
    • Inflammatory dermatologic diseases:
      • Allergic contact dermatitis (soaps, perfumes, or dyes in toilet paper, topical anesthetics, oral antibiotics)
      • Atopic dermatitis ± lichen simplex chronicus (Patients may also have asthma and/or eczema.)
      • Psoriasis (Lesions tend to be poorly demarcated, pale, and nonscaling.)
      • Seborrheic dermatitis
      • Scleroderma
      • Lichen planus (may be seen in patients with ulcerative colitis and myasthenia gravis)
      • Hidradenitis suppurativa
      • Radiation dermatitis (2)
    • Colorectal/anorectal diseases: rectal prolapse, hemorrhoids, fissures or fistulas, proctitis, chronic diarrhea/constipation, polyps
    • Infectious etiologies may be sexually transmitted: bacteria (gonorrhea, chlamydia, syphilis), viruses (herpes simplex virus [HSV], condyloma acuminata from human papillomavirus [HPV], molluscum), parasites (pinworms, lice, scabies, or bed bugs), fungi (Candida or dermatophytes like tinea); other bacteria (Staphylococcus aureus, β-hemolytic Streptococcus, Corynebacterium minutissimum [erythrasma]) (2)
    • Malignancies: melanoma, basal cell/squamous cell carcinoma, colorectal cancer, leukemia, lymphoma, or (uncommon) the presenting symptom of Bowen or Paget disease
    • Mechanical factors: vigorous cleaning and scrubbing, tight-fitting clothes, synthetic undergarments
    • Systemic diseases (often presents as generalized pruritus): diabetes mellitus (most common), cholestasis, chronic liver disease, renal failure, hyperthyroidism, anemia, HIV, vitamin or iron deficiencies, lumbosacral radiculopathy (particularly in the elderly)
    • Chemical irritants: local anesthetics, chemotherapy, diarrhea (often from antibiotic use)
    • Dietary elements (citrus, milk products, coffee, tea, cola, chocolate, beer, wine, tomatoes, nuts)
    • Psychogenic factors: anxiety–itch–anxiety cycle

Risk Factors

  • Obesity
  • Excess perianal hair growth and/or perspiration
  • Underlying anorectal pathology
  • Atopic disease
  • Underlying anxiety disorder
  • Caffeine intake has been correlated with symptoms.

General Prevention

  • Good perianal hygiene; avoid overzealous cleaning.
  • Avoid mechanical irritation of skin (vigorous cleaning or rubbing with dry toilet paper or baby wipes, harsh soaps or perfumed products, excessive scratching with fingernails, or tight/synthetic undergarments).
  • Minimize moisture in perianal area (absorbent cotton in anal cleft may help keep area dry).
  • Avoid laxative use (loose stool is an irritant).

Commonly Associated Conditions

  • Psoriasis is seen in 5–55% of patients with pruritus ani.
  • Coexisting anorectal disease, such as hemorrhoids, can be seen in up to 52% of patients with pruritus ani.

There's more to see -- the rest of this topic is available only to subscribers.