Pruritus Ani (Itchy Bottom)

Pruritus ani is a persistent itch around the anus. There are various causes but the cause is not clear in many cases. Treatment usually works well.

Pruritus ani means a chronic (persistent) itchy feeling around the anus. The main symptom is an urge to scratch your anus, which is difficult to resist. The urge to scratch may occur at any time. However, it tends to be more common after you have been to the toilet to pass a bowel motion, and at night (particularly just before falling asleep). The itch may be made worse by heat, wool, moisture, leaking, soiling, stress and anxiety.

Persistent scratching of the anal skin can damage the skin and make it more likely to develop a skin infection in that area. Also, chronic itching of the anal area may lead to feelings of embarrassment and both your mood and sleep can be affected.

Pruritus ani is a common problem but the exact number of people who get pruritus ani is unknown. However, it does seem to be more common in men than in women. It most commonly affects people between the ages of 40-60 but it can affect children and someone of any age.

Pruritus ani is a symptom, not a final diagnosis. Various conditions may cause pruritus ani and this is known as secondary pruritus ani (because a cause can be identified). However, in many cases the cause is not clear. This is called 'idiopathic pruritus ani' which means 'itchy anus of unknown cause'.

Known causes of pruritus ani

There are various possible causes which include the following:

  • Skin conditions may affect the skin around the anus and cause itch - for example, eczema, psoriasis, lichen sclerosus and seborrhoeic dermatitis. (See separate leaflets called Atopic eczema, Psoriasis, Lichen sclerosus and Seborrhoeic dermatitis of adults that discuss these skin problems in more detail.)
  • An allergic or irritant dermatitis. Dermatitis means inflammation of the skin. This may be caused by:
    • Excess sweat and moisture around the anus. Young children who may not wipe themselves properly, adults with sweaty jobs and adults with a lot of hair round their anus may be especially prone to this.
    • Excess cleaning of the anal area.
    • Some soaps, perfumes, creams, ointments, or the dye in some toilet tissue may sensitise (irritate) the skin around the anus in some people. You may be 'allergic' to one or more of the ingredients in these products.
  • Infections:
    • Thrush and fungal infections are caused by germs that like it best in moist, warm, airless areas, such as around the anus. Thrush is more common in people with diabetes.
    • Other infections such as scabies, infections with bacteria, herpes infection, anal warts and some other sexually transmitted diseases can cause itch around the anus. You are likely to have other symptoms too such as a rash, lump or discharge.
    • Threadworms are a common cause in children. Up to 4 in 10 children in the UK have threadworms at some stage. Threadworms live in the gut and lay eggs around the anus which cause itch. Children may pass them on to adults in the same home. Consider this cause particularly if there is more than one person in the home with an itchy bottom. Also, with threadworms, the itch is mainly at night. (See separate leaflet called Threadworms for more detail.)
  • Some diseases can cause generalised itch, which may seem more intense around the anus at times - for example, lymphoma, liver diseases, iron deficiency anaemia, thyroid gland problems. With these conditions you are likely to be unwell with other symptoms too.
  • Anal fissure. This is a small crack in the anal skin. It is usually painful as well as itchy.
  • Haemorrhoids (piles). (See separate leaflet called Haemorrhoids (piles) for more details.)
  • Some foods are not fully digested and may sensitise the skin around the anus after you have gone to the toilet to pass faeces. These include: citrus fruits, grapes, tomatoes, spices, and drinking large amounts of beer, milk, tea, or coffee.
  • Some medicines:
    • Some antibiotics can lead to diarrhoea. Passing lots of diarrhoea can irritate the anal skin and cause pruritus ani.
    • If you are taking steroid medication or other medicines that can weaken your immune system, you are at increased risk of developing skin infections which may affect the skin around the anus.
    • Medicines that are put on to the anal skin to treat problems such as haemorrhoids may irritate the anal skin and cause a type of dermatitis.
  • A tumour of the anus or rectum is a rare cause of itch around the anus.

Skin conditions and infections are thought to cause over half the cases of secondary pruritus ani.

Idiopathic pruritus ani (of unknown cause)

In many cases, the cause is not clear. In some people, it may be that something is 'sensitising' your skin (such as an ointment that you are using, or your sweat, or the toilet tissue that you use) but you cannot pinpoint the cause exactly.

In other people, it is thought to be caused by a small amount of faeces (stools or motions) leaking from the anus and irritating the nearby skin, causing itching. Also, pruritus ani may affect some people with problems such as depression. However, the cause can sometimes remain a complete mystery.

Pruritus ani and a vicious circle

A 'vicious circle' sometimes develops. For example, you may have a mild anal itch. You may then clean your anus with a scented soap. This may contain an ingredient which sensitises your skin. You then get a worse itch. You may think the itch means the anus needs more cleaning, and so you clean it even more with the scented soap - which makes things worse, and so on.

Another example of a 'vicious circle' is: you may buy an ointment for 'anal conditions' if you have a small haemorrhoid (pile). This may contain an ingredient that your skin is sensitive to, particularly if your skin is already a little inflamed. It may sensitise the skin even more, and the itch becomes worse. You may think that the haemorrhoid has become worse, so you put on more ointment. But, in fact it is the ointment itself making the itch worse, and so on.

Most creams and ointments do not sensitise the skin in most people. However, be aware that there are many preparations with various ingredients, and you may become sensitive to one of them.

If the itch is persistent and you are not sure of the cause, it is best to see a doctor. As there are a number of possible causes (listed above), it is best to be examined and checked out by a doctor to diagnose or rule out known causes. Treatment depends on the cause.

If a cause is found

A particular treatment may be advised by a doctor or pharmacist. For example:

  • You may be advised to use a steroid cream for a short while if there is eczema (dermatitis) around the anus.
  • An antifungal cream will clear fungal infections and thrush.
  • Antibiotics may help with certain other types of infection.
  • Anal conditions such as haemorrhoids or anal fissure may need treatment.
  • A medicine can clear threadworms if they are the cause.

If there is no obvious cause ('idiopathic pruritus ani')

This is a common situation. The following tips often help to stop the itch:

  • Avoid any potential irritants:
    • Stop using scented soaps, talcum powder, bubble bath, perfume, etc, near your anus.
    • Use plain, non-coloured toilet tissue. Wipe your anus gently after passing faeces.
    • Could any foods or medicines be causing the itch? Try avoiding for a while the foods and drinks listed above (such as fruits and tomatoes). Do you take laxatives regularly? Some may be leaking on to your anal skin.
  • Pay special attention to hygiene around your anus:
    • Wash your anus after going to the toilet to pass faeces. The aim is to clear any remnant of faeces which may irritate the skin. Also, wash your anus at bedtime.
    • When washing around your anus, it is best to use water only. If you use soap, use bland non-scented soap.
    • When you are not at home, use a moistened cloth or a special moistened tissue to clean your anus. You can buy moistened tissues from pharmacies.
    • Have a bath or shower daily. If possible, wash your anus with water only. If you use soap around your anus, rinse well.
    • Change your underwear daily.
  • Avoid excessive moisture around your anus:
    • After washing, dry around your anus properly by patting gently (rather than rubbing) with a soft towel. Even better, use a hairdryer, especially if your anal skin is hairy.
    • Do not put on underwear until your anus is fully dry.
    • Wear loose cotton underwear (not nylon). Avoid wearing tight-fitting trousers. If possible, do not sit for long periods, and try not to get too hot. The aim is to allow air to get to your anus as much as possible, and not to get too sweaty.
    • If you sweat and moisture gathers around your anus, put a cotton tissue in your underwear to absorb the moisture.
  • Consider the 'itch-scratch cycle':
    • Scratching can make the itch worse - which makes you want to scratch more, etc.
    • As much as possible, try not to scratch. This is especially difficult at night when the itch tends to be worse when you are trying to get to sleep.
    • You may also scratch in your sleep without realising. To help this:
      • Keep your fingernails short to limit any damage done to the skin by scratching.
      • Consider wearing cotton gloves at night to prevent sharp scratching with fingernails.
      • An antihistamine medicine that makes you drowsy may be worth a try at bedtime. Your doctor will advise.
  • Your doctor may advise a short course of a cream or ointment:
    • A bland soothing ointment may be recommended to use after going to the toilet and at bedtime. There are many to choose from. (However, remember an ingredient of an ointment may sometimes cause sensitivity and itch around the anus.) You should not use a cream such as this for longer than two weeks unless you are advised otherwise by your doctor.
    • A short course (5-7 days) of a mild steroid cream may ease symptoms if there is inflammation of your anal skin. Steroids reduce inflammation (but should not normally be used on infected skin).

The above measures will usually stop the itch. If symptoms persist for three or four weeks after doing the above, then your doctor may refer you to a specialist. This may be a skin specialist (a dermatologist) or a colorectal surgeon (who specialises in problems affecting the colon and anus). Tests may be needed to make sure a known cause has not been missed.

Other possible treatments for pruritus ani are currently being researched. One such new treatment is capsaicin cream. In one research study, 44 people were entered into a trial. These people had long-term pruritus ani with no identifiable cause and had not been helped by standard treatments. Symptoms were eased in 31 of the people in the trial (about 75%). The theory is that capsaicin blocks a chemical in the skin that is involved in sensations of pain and itch. Another treatment involves injecting a chemical called methylthioninium chloride (methylene blue) into and beneath the skin of the anus. Further research is needed to clarify the place of these new treatments.

If a cause for pruritus ani can be identified, it is easier to treat and relieve your symptoms. Most people respond well to treatment for pruritus ani. However, in some people it can become a chronic (persistent) problem. Also, if you have had pruritus ani in the past, you are more likely to develop it again at some point in the future.

Pain or other symptoms such as bleeding from the bowel, mucous discharge, or lumps around the anus are not symptoms of straightforward pruritus ani. See a doctor if these or other symptoms develop in addition to itch.

Original Author:
Dr Tim Kenny
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Last Checked:
19/07/2012
Document ID:
4318 (v40)
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