Anal itching - Causes

The cause of itchy bottom isn't always known. However, it can sometimes be a symptom of another problem or underlying condition.

Infection

An itchy bottom may be a sign that your body is trying to deal with an infection. The infection may be:

• bacterial – such as the streptococcal bacteria that causes streptococcal infections, or the staphylococcal bacteria that causes staphylococcal infections
• fungal – such as the Candida albicans fungus that causes vaginal thrush (itching, irritation and swelling of the vagina and surrounding area)
• parasitic – such as threadworms (small worm parasites that infect the intestines), or scabies (tiny mites that burrow into the skin)
• viral – such as the herpes simplex virus, which causes cold sores

An itchy bottom can sometimes be a symptom of a sexually transmitted infection (STI).

If you've had unprotected sex and think you could have an STI, visit your local sexual health clinic. They can offer advice and provide testing and treatment.

Gastrointestinal conditions

Gastrointestinal conditions affect your digestive tract (your mouth, throat, stomach, intestines and anus).

Gastrointestinal conditions that may cause an itchy bottom include:

• haemorrhoids (piles) – swellings in and around your anus that contain enlarged and swollen blood vessels
• anal fistula – where a small channel (tract) develops between your anal canal (the last section of the large intestine) and the surface of your skin, near the anus
• anal fissure – a tear or ulcer (open sore) that develops in the lining of the anal canal
• sphincter incompetence – where the sphincter (the ring of muscle that opens and closes your anus) stops working properly, causing bowel incontinence
• long-term diarrhoea – passing loose, watery stools
• long-term constipation – an inability to completely empty your bowels

Skin conditions

Some skin conditions can affect any area of skin on your body, including the skin around your anus.

Skin conditions that can be associated with an itchy bottom include:

• psoriasis – where red, flaky, crusty patches of skin develop because your skin cells reproduce too quickly
• contact dermatitis – where your skin reacts to certain substances (allergens), causing it to become inflamed
• lichen sclerosus – a long-term skin disorder that causes itchy or sore white spots to develop on the skin around the genitals
• atopic eczema – where your skin becomes dry, red and flaky

Systemic conditions

Systemic conditions affect your whole body and can sometimes make your bottom feel itchy. Systemic conditions include:

• diabetes – a lifelong condition that causes your blood sugar level to become too high
• kidney failure – where your kidneys stop working properly
• iron deficiency anaemia – a decrease in the number of red, oxygen-carrying blood cells, causing tiredness and a lack of energy (lethargy) 
• overactive thyroid (hyperthyroidism) – too much thyroid hormone in your body

Medication

Some types of medication, including those applied directly to your skin (topical), may make your bottom feel itchy.

For example, if you use a cream to treat haemorrhoids, it may irritate the sensitive skin around your anus and make the itching worse.

Some topical medicines may also cause contact dermatitis (red, itchy skin) if used for long periods.

Medicines that may cause an itchy bottom or make your symptoms worse include:

• peppermint oil – which is sometimes used to help relieve stomach cramps
• long-term use of local anaesthetics – medicines that numb a specific part of your body
• glyceryl trinitrate – which is often prescribed as a topical cream to treat anal fissures, and may cause itching 
• long-term use of topical corticosteroids – medicines applied directly to the skin to help reduce inflammation

If a medicine you're taking is causing an itchy bottom, your bottom should itch less after you've completed the course of medication.

Never stop taking a prescribed medication unless advised to do so by your GP or other qualified healthcare professional responsible for your care.

Speak to your GP if you're taking a medicine on a long-term basis and it's causing an itchy bottom. They may be able to prescribe an alternative.

Anal and bowel cancer

In rare cases, itchy bottom can be a symptom of a gastrointestinal cancer, such as anal cancer or bowel cancer.

Most cases of itchy bottom aren't caused by cancer, but it's important that your GP rules out all possibilities.

Possible symptoms of anal cancer include:

• rectal bleeding
• pain
• itching
• small lumps that develop around the anus

Possible symptoms of bowel cancer include:

• bleeding from the back passage
• blood in your stools
• a change in your normal bowel habits, such as diarrhoea that lasts longer than four to six weeks