Anusitis – Causes, Symptoms, Diagnosis, Treatment

Anusitis may happen secondary to ulcerative colitis (UC), Chronic Radiation Proctitis, Proctopathy (CRP), or Diversion Proctitis (DP). Infectious causes include Clostridium difficile, enteric infections (Campylobacter, Shigella, Escherichia coli, Salmonella, and amebiasis), and STI’s (Gonorrhea, Chlamydia, Syphilis, HSV, Lymphogranuloma venereum, chancroid, CMV, HPV). Other causes include ischemia, vasculitis, toxins as hydrogen peroxide enemas or medication side effects. The most common cause of anusitis is diet, as with excess citrus, coffee, cola, beer, garlic, spices, and sauces. Diarrhea noted after intake of laxatives as in preparation for colonoscopy is noted to cause anusitis and stress may be another etiologic factor.

Anusitis is a disorder that involves inflammation of the anal canal. People often mistake anusitis for hemorrhoids. Inflammatory bowel disease, infections, and chronic diarrhea can cause anusitis. However, the most common cause is a diet that contains a lot of acidic or spicy foods, such as coffee, citrus, and spices.

Causes of Anusitis

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 sclerosis.
  • 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.


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

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

  • Lymphoma
  • Certain liver diseases
  • Iron-deficiency anemia
  • 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. These 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.

Diagnosis Of Anusitis

  • Physical exam and history – An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
  • Blood tests – These can detect blood loss or infections.
  • Stool test – You may be asked to collect a stool sample for testing. A stool test may help determine if your proctitis is caused by a bacterial infection.
  • Scope exam of the last portion of your colon – During this test (flexible sigmoidoscopy), your doctor uses a slender, flexible, lighted tube to examine the last part of your colon (sigmoid), as well as the rectum. During the procedure, your doctor can also take small samples of tissue (biopsy) for laboratory analysis.
  • Scope exam of your entire colon – This test (colonoscopy) allows your doctor to view your entire colon using a thin, flexible, lighted tube with an attached camera. Your doctor can also take a biopsy during this test.
  • Tests for sexually transmitted infections – These tests involve obtaining a sample of discharge from your anus or from the tube that drains urine from your bladder (urethra).
  • Digital anus exam (DRE) – An exam of the anus. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual. In women, the vagina may also be examined.
  • Biopsy – The removal of cells or tissues so they can be viewed under a microscope to check for signs of the anus. Anus tissue that is removed during the biopsy may be checked to see if the patient is likely to have the gene mutation that causes HNPCC. This may help to plan treatment.

The following treatment is available for anusitis

  • Antibiotic – Gonococcal proctitis is treated with ceftriaxone 250 mg intramuscular one time plus azithromycin 1 gram oral one time.
  • An alternative regimen is cefixime 400 mg -moral one time plus doxycycline 100 mg oral twice daily for seven days.mChlamydia is treated with azithromycin.
  • Doxycycline – erythromycin, ofloxacin, or Levofloxacin may be used as an alternative regimen.
  • LGV – has treated with doxycycline 100 mg twice daily for 21 days.
  • Erythromycin or azithromycin – may be used as alternative regimens for the same period of 21 days.
  • Herpes proctitis – is treated with acyclovir 400 mg oral three times daily or valacyclovir 1 gram twice daily or famciclovir 250 mg three times daily for 7 to 10 days. The course of treatment may be extended if no complete healing is achieved by the end of the 10-day course of treatment.

For patients with mild to moderate UP, guidelines from American College of Gastroenterology (ACG) and American Gastroenterological Association (AGA) recommend

  • Rectal 5-Aminosalicylic Acid (5-ASA) – mesalamine rather than oral mesalamine. Suppositories are more effective than enemas. For induction of remission, the dose is 1 g/day and this is to be continued at the same dose to maintain remission.
  • Anus therapy – In cases of intolerance, refractoriness, hypersensitivity to mesalamine suppositories, inability to retain rectal therapy, rectal corticosteroid therapy is suggested for induction of remission rather than no therapy, despite the superiority of rectal 5-ASA over rectal steroids.
  • Corticosteroids – are not recommended and are not effective in the maintenance of remission secondary to side effects and long-term complications. Up to 46% of patients with UP may develop extensive colitis. This should be especially suspected in patients refractory to topical treatment and follow-up is recommended.
  • UP is treated with topical mesalazine – in the form of suppositories, enemas, foams, and gels in severe cases combined with oral mesalazine with topical steroids or systemic corticosteroids in more severe cases.
  • In steroid-resistant cases – the addition of cyclosporine or immunomodulators; thiopurines as azathioprine (AZA) and 6-mercaptopurine (6-MP) is considered. Other options include anti-TNF-α (infliximab, adalimumab, and golimumab), anti-integrin antibodies as vedolizumab, and certolizumab, or oral tacrolimus.

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.

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-colored toilet tissue. Wipe your anus gently after passing stools (feces).
  • 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.
    • 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 (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).


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