Pruritus ani

Infobox_Disease
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Caption =
DiseasesDB = 30154
ICD10 = ICD10|L|29|0|l|20
ICD9 = ICD9|698.0
ICDO =
OMIM =
MedlinePlus =
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Pruritus ani is the irritation of the skin at the exit of the rectum, known as the anus, causing the desire to scratch. The intensity of anal itching increases from moisture, pressure, and rubbing caused by clothing and sitting. At worst, anal itching causes intolerable discomfort that often is accompanied by burning and soreness.

Causes

Anal itching can be caused by irritating chemicals in the foods consumed, such as are found in:

* Spices, hot sauces, and peppers
* Coffee, tea
* Carbonated beverages
* Milk products
* Tomatoes and tomato products, such as Ketchup
* Cheese
* Chocolate
* Nuts

It also can be caused by the irritation of frequent liquid stools, diarrhea, or the escape of small amounts of stool (incontinence). Another main cause is yeast infection or Candidiasis.

Some diseases increase the possibility of yeast infections, such as diabetes mellitus or HIV infection. Treatment with antibiotics can lead to a yeast infection and irritation of the anus. Psoriasis also can irritate the anus. Abnormal passageways (fistulas) from the small intestine or colon to the skin surrounding the anus can form as a result of disease (such as Crohn's disease), and these fistulas bring irritating fluids to the anal area. Other problems that can cause anal itching include pinworms, hemorrhoids, tears of the anal skin (fissures), and skin tags (abnormal local growth of anal skin).

Treatment

Initial treatment of simple itching is directed toward relieving the burning and soreness. It is important to clean and dry the anus thoroughly and avoid leaving soap in the anal area. Cleaning efforts should include gentle showering without direct rubbing or irritation of the skin with either the washcloth or towel. After bowel movements, moist pads should be used for cleaning the anus instead of toilet paper.

Many over-the-counter products are sold for the treatment of anal itching. These often contain the same drugs that are used for treating hemorrhoids. Products used for the treatment of anal itching are available as ointments, creams, gels, suppositories, foams, and pads. Ointments, creams, and gels--when used around the anus--should be applied as a thin covering. When applied to the anal canal, these products should be inserted with a finger or a "pile pipe." Pile pipes are most efficient when they have holes on the sides as well as at the end. Pile pipes should be lubricated with ointment prior to insertion. Suppositories or foams do not have advantages over ointments, creams, and gels.

Most products contain more than one type of active ingredient. Almost all contain a protectant in addition to another ingredient. Only examples of brand-name products containing one ingredient in addition to the protectant are discussed below.

Local anesthetics

Local anesthetics temporarily relieve pain, burning, and itching by numbing the nerve endings. The use of these products should be limited to the perianal area and lower anal canal. Local anesthetics can cause allergic reactions with burning and itching. Therefore, if burning and itching increase with the application of anesthetics, they should be discontinued. Local anesthetics include:

*Benzocaine 5% to 20% (Americaine Hemorrhoidal, Lanacane Maximum Strength, Medicone)
*Benzyl alcohol 5% to 20%
*Dibucaine 0.25% to 1.0% (Nupercainal)
*Dyclonine 0.5% to 1.0%
*Lidocaine 2% to 5%
*Pramoxine 1.0% (Fleet Pain-Relief, Procto Foam Non-steroid, Tronothane Hydrochloride)
*Tetracaine 0.5% to 5.0%

Vasoconstrictors

Vasoconstrictors are chemicals that resemble epinephrine, a naturally occurring chemical. Applied to the anus, vasoconstrictors make the blood vessels become smaller, which may reduce swelling. They also may reduce pain and itching due to their mild anesthetic effect. Vasoconstrictors applied to the perianal area--unlike vasoconstrictors that are taken orally or by injection--have a low likelihood of causing serious side effects, such as high blood pressure, nervousness, tremor, sleeplessness, and aggravation of diabetes or hyperthyroidism. Vasoconstrictors include:

*Ephedrine sulfate 0.1% to 1.25%
*Epinephrine 0.005% to 0.01%
*Phenylephrine 0.25% (Medicone Suppository, Preparation H, Rectacaine)

Protectants

Protectants prevent irritation of the perianal area by forming a physical barrier on the skin that prevents contact of the irritated skin with aggravating liquid or stool from the rectum. This barrier reduces irritation, itching, pain, and burning. There are many products that are themselves protectants or that contain a protectant in addition to other medications. Protectants include:

*Aluminum hydroxide gel
*Cocoa butter
*Glycerin
*Kaolin
*Lanolin
*Mineral oil (Balneol)
*Petroleum jelly
*Starch
*Zinc oxide or calamine (which contains zinc oxide) in concentrations of up to 25%
*Cod liver oil or shark liver oil if the amount of vitamin A is 10,000 USP units/day.

Astringents

Astringents cause coagulation (clumping) of proteins in the cells of the perianal skin or the lining of the anal canal. This action promotes dryness of the skin, which in turn helps relieve burning, itching, and pain. Astringents include:

*Calamine 5% to 25%
*Zinc oxide 5% to 25% (Calmol 4, Nupercainal, Tronolane)
*Witch hazel 10% to 50% (Fleet Medicated, Tucks, Witch Hazel Hemorrhoidal Pads)

Antiseptics

Antiseptics inhibit the growth of bacteria and other organisms. However, it is unclear whether antiseptics are any more effective than soap and water. Examples of antiseptics include:

*Boric acid
*Hydrastis
*Phenol
*Benzalkonium chloride
*Cetylpyridinium chloride
*Benzethonium chloride
*Resorcinol

Keratolytics

Keratolytics are chemicals that cause the outer layers of skin or other tissues to disintegrate. The rationale for their use is that the disintegration allows medications that are applied to the anus and perianal area to penetrate into the deeper tissues. The two approved keratolytics used are:

*Aluminum chlorhydroxy allantoinate (alcloxa) 0.2% to 2.0%
*Resorcinol 1% to 3% Analgesics

Analgesic products, like anesthetic products, relieve pain, itching, and burning by depressing receptors on pain nerves. Examples include:

*Menthol 0.1% to 1.0% (greater than 1.0% is not recommended)
*Camphor 0.1% to 3% (greater than 3% is not recommended)
*Juniper tar 1% to 5%

Corticosteroids

Corticosteroids reduce inflammation and can relieve itching, but their chronic use can cause permanent damage to the skin. They should not be used for more than short periods of a few days to two weeks. Only products with weak corticosteroid effects are available over-the-counter. Stronger corticosteroid products are available by prescription.

*The OTC medication Lotrimin cream mixed with hydrocortisone 1% cream can be applied daily. A mild alphahydroxyacid cream can help, as can plain vaseline applied each day to the anal area
*Methylpred 4mg (methylprednisolone tapered dose pack) has shown remission of symptoms in some cases.

For persistent anal itching, efforts are directed toward identifying an underlying cause. An examination by a doctor can rapidly identify most causes of anal itching. Adjustments in diet, treatment of infections, or surgical procedures to correct the underlying cause may be required.