Anal Itching (Pruritus Ani)

Picture of Anus

Anal itching (known medically as pruritus ani) is irritation of the skin at the opening of the anal canal through which stool exits the body which leads to itching. The skin surrounding the opening is known as the anus. The itching is accompanied by the desire to scratch. Although itching may be a reaction to chemicals in the stool, it often implies that there is inflammation of the anal area. The intensity of anal itching and inflammation increases with the direct trauma of scratching and the presence of moisture. At its most intense, anal itching causes intolerable discomfort, often described as burning and soreness.

External hemorrhoids are located underneath the skin that surrounds the anus and is lower than internal hemorrhoids.

• An itchy bottom can be caused by irritating chemicals in the foods we eat, such as are found in spices, hot sauces, and peppers.
• Anal itching also can be caused by the irritation of continuous moisture in the anus from frequent liquid stools, diarrhea, or escape of small amounts of stool (incontinence or fecal spoilage). Moisture increases the possibility of infections of the anus, especially yeast, particularly in patients with diabetes or HIV.
• Treatment with antibiotics can lead to a yeast infection and irritation of the anus.
• Psoriasis 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 medical conditions (such as Crohn's disease), and these fistulas bring irritating fluids to the anal area.
• Rarely, tumors of the anus (anal cancer) may be the cause of itching.

Other problems that can cause anal itch include:

• Pinworms
• Hemorrhoids
• Tears of the anal skin (fissures)
• Skin tags (abnormal local growth of anal skin)

At its most intense, anal itching causes intolerable discomfort that often is described as burning and soreness.

The intensity of anal itching and the amount of inflammation increases from the direct trauma of scratching and the presence of moisture. At its most intense, anal itching causes intolerable discomfort that often is described as burning and soreness, especially during and after bowel movements. There also may be small amounts of bleeding.

Although anal itching can be evaluated by a family practice or internal medicine physician, it most often is evaluated by a colorectal surgeon (proctologist) and sometimes by a gastroenterologist.

Anal itching is first evaluated with a careful examination of the anus for such abnormalities as hemorrhoids, anal fissures, skin tags, moisture, and excoriations (breaks in the skin from scratching).

A rectal examination with a finger inserted into the anal canal can identify rectal tumors. For a closer look at the anal canal, a proctoscope can be used. A proctoscope is a short tube that is inserted through the anus and into the rectum so that the anal canal can be examined visually If pinworms are suspected, they and their eggs can be identified using the pinworm test, a test in which the worms and eggs are recovered from the anus using transparent adhesive tape.

Initial self-care for simple itching is directed toward relieving symptoms, like 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 (such as baby wipes, flushable moist wipes, and flushable anal cleansing wipes) should be used for cleaning the anus instead of toilet paper.
• If there is constant moisture present in the anus or stool incontinence, it may be necessary to clean the anus with wet wipes between bowel movements.

Many over-the-counter (OTC) products are sold for the treatment of an itchy anus and are available as ointments, creams, gels, suppositories, foams, and pads. These products often contain the same drugs used to treat hemorrhoids.

• When used around the anus, ointments, creams, and gels should be applied as a thin covering.
• When applied to the anal canal, these products should be inserted with a finger using finger cots (latex covers for the fingertips) 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 before 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 in this article.

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, the application of anesthetics should be discontinued if burning and itching increase.

Examples of local anesthetics include:

• benzocaine 5% to 20% (Americaine Hemorrhoidal, Lanacane Maximum Strength, Medicone)
• benzyl alcohol (Itch-X) 5% to 20%
• dibucaine 0.25% to 1.0% (Nupercainal)
• dyclonine 0.5% to 1.0%
• lidocaine (Xylocaine) 2% to 5%
• pramoxine 1.0% (Fleet Pain-Relief, Procto Foam Non-steroid, Tronothane Hydrochloride)
• tetracaine 0.5% to 5.0%

Vasoconstrictors are chemicals such as epinephrine, a naturally occurring chemical. Applied to the anus, vasoconstrictors make the blood vessels become smaller, which may reduce swelling. They also may reduce symptoms due to their mild anesthetic effect.

Vasoconstrictors applied to the perianal area -- unlike vasoconstrictors given 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.

Examples of vasoconstrictors include:

• ephedrine sulfate 0.1% to 1.25%
• epinephrine 0.005% to 0.01%
• phenylephrine 0.25% (Medicone Suppository, Preparation H, Rectocaine)

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.

Examples of protectants include:

• aluminum hydroxide gel
• cocoa butter
• glycerin
• kaolin
• lanolin
• mineral oil (Balneol)
• white petrolatum
• starch
• zinc oxide (Desitin) 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 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.

Examples of 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 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
• phenol
• benzalkonium chloride
• cetylpyridinium chloride
• benzethonium chloride
• resorcinol

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 the deeper tissues.

The two approved keratolytic used are:

• aluminum chlorhydroxy allantoinate (alcloxa) 0.2% to 2.0%
• resorcinol 1% to 3%

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

Examples of analgesics include:

• menthol 0.1% to 1.0% (greater than 1.0% is not recommended) (Calmoseptine)
• camphor 0.1% to 3% (greater than 3% is not recommended)
• juniper tar 1% to 5%

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 that are available by prescription should not be used for treating anal itching.

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