Itchy bottom

What is pruritus ani?

Pruritus ani is the medical term for a persistent (chronic) 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.

• Wearing woollen clothes.

• Moisture or wetness around the anus. This may be caused by sweating, or by incomplete drying of that area after washing. It may also be caused by leaking urine (incontinence).

• Stools (faeces) being in contact with the skin around the anus. This can be due to leaking of stools out of the anus, or due to incomplete cleaning after opening your bowels.

• 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. Both your mood and sleep can be affected.

Who develops an itchy bottom?

An itchy bottom (pruritus ani) is a common problem but the exact number of people who develop an itchy bottom is unknown. Some sources suggest around 1 to 5 out of every 100 people have an itchy bottom, though this may be an underestimate as some may not seek medical attention. It seems to be about four times more common in men than in women. It most commonly affects people between the ages of 40-60. However, it can affect people of any age, including children.

What causes an itchy bottom?

An itchy bottom (pruritus ani) is a symptom, not a final diagnosis. Various conditions may cause an itchy bottom. When the cause is another condition which has been identified, this is known as secondary pruritus ani. However, in many cases the cause is not clear. This is called 'idiopathic pruritus ani' which means 'itchy anus of unknown cause'. Up to 90% of cases of pruritus ani may be idiopathic.

There are lots of possible causes. See the separate leaflets linked to each condition below for more detail. These are just some of the possible causes:

Skin conditions

There are a number of skin conditions which may affect the skin around the anus and cause itch. For example:

• Eczema.

• Psoriasis.

• Lichen sclerosus.

• Lichen planus.

• Seborrhoeic dermatitis.

• 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, or ointments, or the dye in some toilet tissue, may irritate (sensitise) the skin around the anus in some people. You may be allergic to one or more of the ingredients in these products.

Skin conditions cause about half of all cases of secondary pruritus ani.

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Infections

• Thrush and fungal infections are caused by germs that thrive in moist, warm, airless areas, such as around the anus. Thrush is more common in people with diabetes.

• Threadworms are a very 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.

• Other infections such as scabies, infections with germs (bacteria), herpes infection, anal warts and some other sexually transmitted infections can cause itch around the anus. You are likely to have other symptoms too such as a rash, lump or discharge.

Conditions affecting the anus

These include:

• Anal fissure. This is a small crack in the anal skin. It is usually painful as well as itchy.

• Piles (haemorrhoids).

• A tumour of the anus or lower gut (bowel and rectum) is a rare cause of an itch around the anus.

Some diseases

Generalised itch, which may seem more intense around the anus at times, may be caused by some diseases. For example:

• Lymphoma.

• Certain liver diseases.

• Iron-deficiency anaemia.

• Thyroid gland problems.

• Diabetes.

With these conditions you are likely to be unwell with other symptoms.

Some foods

When certain foods are not fully digested, they may irritate the skin around the anus after you have gone to the toilet to pass stools. The foods that may cause anal itching include::

• Citrus fruits.

• Grapes.

• Tomatoes.

• Spices and chilli peppers.

• Large amounts of beer.

• Milk.

• Caffeine - in coffee, tea or cola.

Some medicines

• Some antibiotics can lead to diarrhoea. Passing lots of diarrhoea can irritate the anal skin and cause an itchy bottom.

• 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.

• Other medicines such as colchicine (for gout) and peppermint oil (for wind and bloating) may cause an itchy bottom as a side-effect.

• Medicines that are put on to the skin near the anus to treat problems such as haemorrhoids may irritate the anal skin and cause a type of dermatitis.

Unknown causes of an itchy bottom (idiopathic pruritus ani)

In many cases, the cause is not clear. In some people, it may be that something is irritating your skin. This may be 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 stool leaking from the anus and irritating the nearby skin, causing itching. Also, an itchy bottom may affect some people with problems such as depression. However, the cause can sometimes remain a complete mystery.

An itchy bottom and a vicious circle

A 'vicious circle' (itch-scratch cycle) sometimes develops. The more you scratch, the more irritated the skin becomes and the more it itches. Various factors can keep this cycle going. For example, you may have a mild itch around your anus. You may then clean your anus with a scented soap. This may contain an ingredient which irritates your skin. You then develop a worse itch. You may think the itch means the anus needs more cleaning. Therefore, 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 if you have a small pile (haemorrhoid). 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 is making the itching worse and so on.

Most creams and ointments do not irritate 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.

How to stop an itchy bottom

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.

Pruritus ani treatment

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 piles (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 stools (faeces).

  • If any foods or medicines could be causing the itch, try avoiding for a while the foods and drinks listed above (such as fruits and tomatoes). If you take laxatives regularly, some of your stool 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 stools. The aim is to clear any remnant of stool 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. Avoid scented or perfumed versions.

  • 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 to avoid getting 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 while 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.

    • Wear 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 (up to 14 days but no more) 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).

Other possible treatments

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 an itchy bottom (pruritus ani) are currently being researched. One such treatment is capsaicin cream. 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. This would only be done via a hospital clinic. Further research is needed to clarify the place of these new treatments.

What is the outlook (prognosis) for an itchy bottom?

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