Itchy bottom: causes, red flags and when to get it checked

The skin around the anus is thin, moist and exposed to irritants such as stool, sweat and soap. When it is damaged or inflamed it itches intensely. Often the cause is simple, yet the habit of vigorous wiping and scratching can sustain it for months.

• Poor or excessive hygiene: too little wiping leaves stool residue, too much scrubbing or perfumed wipes irritates skin.

• Moisture from sweating, tight clothing and loose stools or minor leakage.

• Haemorrhoids and skin tags, which trap moisture and stool.

• Contact dermatitis from soaps, wipes, creams and toilet paper.

• Eczema, psoriasis and lichen sclerosus affecting the area.

• Threadworms, especially in children and households, with night itching.

• Fungal infection (candida) and bacterial infection, particularly in diabetes or after antibiotics.

• Anal fissure or fistula, and rarely anal cancer or Bowen disease, which cause persistent changes.

Persistent itching despite treatment, a lump, bleeding, pain, ulceration, white or red patches, a discharge or change in bowel habit, and risk factors such as immunosuppression or previous anal warts warrant examination.

• Urgent GP: an anal lump, ulcer, persistent bleeding or pain, particularly if the itch continues over several weeks.

• GP within a week or two: itching not responding to a week or two of self-care.

• Same-day GP: severe pain, fever or swelling suggesting an abscess.

• Pharmacist: itching with suspected threadworms in the household.

The doctor asks about duration, timing, hygiene practices, products used, diet (coffee, spicy foods), bowel habit, leakage, skin conditions, diabetes and threadworm contact. They inspect the skin and perform a rectal examination and sometimes proctoscopy.

• Visual examination and proctoscopy: look for haemorrhoids, fissures and skin changes.

• Skin swab or scrapings: for fungal or bacterial infection.

• Sellotape test: for threadworm eggs, in children especially.

• Blood glucose or HbA1c: to look for diabetes.

• Biopsy of any suspicious skin lesion.

Wash gently with plain water after a bowel movement and pat dry rather than rubbing; avoid perfumed soaps and wipes. Wear loose cotton underwear, avoid scratching, keep nails short, and use a barrier cream. Reduce coffee, tea, and spicy foods if they appear to trigger itching. Treat constipation or loose stools. Treat threadworms with household medication from a pharmacist.

The NHS route is a pharmacist or GP, then dermatology or colorectal clinics. Private dermatology and colorectal consultations are available directly.