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. It is estimated that up to 5% of the population of the United States experiences this type of discomfort daily.

If a specific cause for pruritus ani is found it is classified as "secondary pruritus ani". If a specific cause is NOT found it is classified as "idiopathic pruritus ani". The irritation can be caused by intestinal parasites, anal perspiration, frequent liquid stools, diarrhea, residual stool deposits, or the escape of small amounts of stool as a result of incontinence or flatulence. Another 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 bring about a disturbance of the natural balance of intestinal flora, and lead to perianal thrush, a yeast infection affecting the anus. Psoriasis also can be present in the anal area and cause irritation. 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), acting as channels which may allow leakage of irritating fluids to the anal area. Other problems that can contribute to anal itching include pinworms, hemorrhoids, tears of the anal skin near the mucocutaneous junction (fissures), and skin tags (abnormal local growth of anal skin). Aside from diseases relative to the condition, a common view suggests that the initial cause of the itch may have passed, and that the illness is in fact prolonged by what is known as an itch-scratch-itch cycle. It states that scratching the itch encourages the release of inflammatory chemicals, which worsen redness, intensifies itchiness and increases the area covered by dry skin, thereby causing a snowball effect.

Some authorities describe “psychogenic pruritus” or "functional itch disorder", where psychological factors may contribute to awareness of itching.

Ingestion of helminth (worm) "Enterobius vermicularis" (pinworm, or threadworm) eggs leads to enterobiasis, indicative of severe itching around the anus from migration of gravid females from the bowel. Severe cases of enterobiasis result in hemorrhage and eczema.

One of the most common areas of the body associated with irritation is the vagina. Many women complain of an itch, dryness, or discharge in the perineum at some point in their lives. There are several causes of vaginal irritation including fungal vaginitis (like candida) or trichomoniasis. Often, herpes simplex infection of the mouth or genitalia can be recurrent and prove to be extremely irritating.

Sometimes, the irritation can be of the chronic type and it can be so intense that it also causes painful intercourse. Aside from infections, chronic irritation of the vagina may be related to the use of contraceptives and condoms made from latex. The majority of contraceptives are made of synthetic chemicals which can induce allergies, rash and itching. Sometimes the lubricant used for intercourse may cause irritation.

Another cause of irritation in women is post menopausal vaginitis. The decline in the female sex hormones leads to development of dryness and itching in the vagina. This is often accompanied by painful sexual intercourse. Cracks and tears often develop on outer aspects of the labia which becomes red from chronic scratching. Post menopausal vaginitis can be treated with short term use of vaginal estrogen pessary and use of a moisturizer.

No definitive medical test is known for aquagenic pruritus. Rather, the diagnosis is made by excluding all other possible causes of the patient's itching. Some of which includes polycythemia vera. Since pruritus is a symptom of many serious diseases, it is important to rule out other causes before making a final diagnosis.

Symptoms occur for up to 35 minutes; duration of an attack is typically between 10 and 120 minutes. However, sensitivity varies among sufferers, and since water is always present to some extent in the air (atmospheric humidity), those with greater sensitivity who live in moister regions are symptomatic almost constantly, while perspiration can cause frequent symptoms even in the driest climates.

Gastritis or stomach upset is a common irritating disorder affecting millions of people. Gastritis is basically inflammation of the stomach wall lining and has many causes. Smoking, excess alcohol consumption and the use of non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, account for the majority of causes of gastritis. In some cases, gastritis may develop after surgery, a major burn, infection or emotional stress. The most common symptoms of gastritis include sharp abdominal pain which may radiate to the back. This may be associated with nausea, vomiting, abdominal bloating and a lack of appetite. When the condition is severe it may even result in loss of blood on the stools. The condition often comes and goes for years because most people continue to drink alcohol or use NSAIDs. Treatment includes the use of antacids or acid neutralizing drugs, antibiotics, and avoiding spicy food and alcohol.

People burdened with LSC report pruritus, followed by uncontrollable scratching of the same body region, excessively. Most common sites of LSC are the sides of the neck, the scalp, ankles, vulva, pubis, scrotum, and extensor sides of the forearms. However, due to the stigma associated with chronic scratching, some patients will not admit to chronic rubbing or abrasion. The skin may become thickened and hyperpigmented (lichenified) as a direct result of chronic exoriation. Typically this period of increased scratching is associated with stressors.

There are many different types of rectal discharge, but the most common presentation of a discharge is passage of mucus or pus wrapped around an otherwise normal bowel movement.

Rectal discharge has many causes, and may present with other symptoms:

- Staining of undergarments

- Constant feeling of dampness around anus

- Frequent urge to open bowels, but passage of only small amounts of mucus or pus-like liquid rather than normal feces

- Rectal pain

- Rectal malodor, when the discharge is foul-smelling, e.g. associated with certain infections

- Pruritus ani

- Rectal bleeding

- Perianal erythema, swelling and tenderness

Pus usually indicates infection. Frequently medical sources do not differentiate between the two types of discharge, instead using the general term mucopurulent discharge, which, strictly speaking, should only be used to refer to a discharge that contains both mucus and pus. Purulent discharges may be blood-streaked.

Lichen simplex chronicus (LSC) (also known as "Neurodermatitis") is a skin disorder characterized by chronic itching and scratching. The constant scratching causes thick, leathery, darkened, (lichenified) skin. This condition is associated with many factors, including the scratch-itch cycle, psychological stressors, and atopy. LSC is more common between ages 35 and 50 and is seen approximately twice as often in women compared to men.

A common symptom is a continual urge to have a bowel movement—the rectum could feel full or have constipation. Another is tenderness and mild irritation in the rectum and anal region. A serious symptom is pus and blood in the discharge, accompanied by cramps and pain during the bowel movement. If there is severe bleeding, anemia can result, showing symptoms such as pale skin, irritability, weakness, dizziness, brittle nails, and shortness of breath.

Symptoms are ineffectual straining to empty the bowels, diarrhea, rectal bleeding and possible discharge, a feeling of not having adequately emptied the bowels, involuntary spasms and cramping during bowel movements, left-sided abdominal pain, passage of mucus through the rectum, and anorectal pain.

Vulvitis is inflammation of the vulva, the external female mammalian genitalia that include the labia majora, labia minora, clitoris, and introitus (the entrance to the vagina). It may co-occur with vaginitis, inflammation of the vagina, and may have infectious or non-infectious causes.

Internal hemorrhoids usually present with painless, bright red rectal bleeding during or following a bowel movement. The blood typically covers the stool (a condition known as hematochezia), is on the toilet paper, or drips into the toilet bowl. The stool itself is usually normally coloured. Other symptoms may include mucous discharge, a perianal mass if they prolapse through the anus, itchiness, and fecal incontinence. Internal hemorrhoids are usually only painful if they become thrombosed or necrotic.

Itchiness, a burning sensation, pus discharge, blood, and swelling in around the rectum and anus, diarrhea.

Keriorrhea (oily diarrhea, oily orange diarrhea, anal leakage, orange oily leakage) is the production of greasy, orange-colored stools which results from the consumption of indigestible wax esters found in oil fish and escolar.

If not thrombosed, external hemorrhoids may cause few problems. However, when thrombosed, hemorrhoids may be very painful. Nevertheless, this pain typically resolves in two to three days. The swelling may, however, take a few weeks to disappear. A skin tag may remain after healing. If hemorrhoids are large and cause issues with hygiene, they may produce irritation of the surrounding skin, and thus itchiness around the anus.

Vulvitis, inflammation of the vulva, can have a variety of etiologies in children and adolescents, including allergic dermatitis, contact dermatitis, lichen sclerosus, and infections with bacteria, fungi, and parasites. Dermatitis in infants is commonly caused by a soiled diaper being left on for an extended period of time. Increasing the frequency of diaper changes and topical application of emollients are sufficient to resolve most cases. Dermatitis of the vulva in older children is usually caused by exposure to an irritant (e.g. scented products that come into contact with the vulva, laundry detergent, soaps, etc.) and is treated with preventing exposure and encouraging sitz baths with baking soda as the vulvar skin heals. Other treatment options for vulvar dermatitis include oral hydroxyzine hydrochloride or topical hydrocortisone.

Lichen sclerosus is another common cause of vulvitis in children, and it often affects an hourglass or figure eight-shaped area of skin around the anus and vulva. Symptoms of a mild case include skin fissures, loss of skin pigment (hypopigmentation), skin atrophy, a parchment-like texture to the skin, dysuria, itching, discomfort, and excoriation. In more severe cases, the vulva may become discolored, developing dark purple bruising (ecchymosis), bleeding, scarring, attenuation of the labia minora, and fissures and bleeding affecting the posterior fourchette. Its cause is unknown, but likely genetic or autoimmune, and it is unconnected to malignancy in children. If the skin changes are not obvious on visual inspection, a biopsy of the skin may be performed to acquire an exact diagnosis. Treatment for vulvar lichen sclerosus may consist of topical hydrocortisone in mild cases, or stronger topical steroids (e.g. clobetasol propionate). Preliminary studies show that 75% of cases do not resolve with puberty.

Organisms responsible for vulvitis in children include pinworms ("Enterobius vermicularis"), "Candida" yeast, and group A hemolytic "Streptococcus". Though pinworms mainly affect the perianal area, they can cause itching and irritation to the vulva as well. Pinworms are treated with albendazole. Vulvar "Candida" infections are uncommon in children, and generally occur in infants after antibiotic therapy, and in children with diabetes or immunodeficiency. "Candida" infections cause a red raised vulvar rash with satellite lesions and clear borders, and are diagnosed by microscopically examining a sample treated with potassium hydroxide for hyphae. They are treated with topical butoconazole, clotrimazole, or miconazole. "Streptococcus" infections are characterized by a dark red discoloration of the vulva and introitus, and cause pain, itching, bleeding, and dysuria. They are treated with antibiotics.

The areas most affected are the toes, fingers, earlobes, nose.

- Blistering of affected area

- Burning and itching sensation in extremities

- Dermatitis in extremities

- Digital ulceration (severe cases only)

- Erythema (blanchable redness of the skin)

- Pain in affected area

- Skin discoloration, red to dark blue

Chilblains usually heal within 7–14 days.

Perianal cellulitis (also known as "Perineal dermatitis," and "Streptococcal perianal disease") is a cutaneous condition that presents as sharply demarcated, bright, perianal erythema extending 2–3 cm around the anal verge.

The upper GI tract is defined as the organs involved in digestion above the ligament of Treitz and comprises the esophagus, stomach, and duodenum. Upper gastrointestinal bleeding is typically characterized by melena (black stool). Bright red blood may be seen with active, rapid bleeding.

Two more highly common causes of functional anorectal pain are levator ani syndrome (LAS) and proctalgia fugax. Both of these conditions are thought to be caused by muscle spasms of the either the levator ani muscle or the anal sphincter muscle respectively, and may overlap symptomatically with a third less-common condition called coccygodynia which is the result of previous trauma to the coccyx bone. Stress, prolonged sitting, and constipation all seem to be associated with LAS. The majority (90%) of those reporting chronic episodes of such pain are women. Some researchers group these conditions under the medical category of "tension myalgia of the pelvic floor". Less than a third of those experiencing these conditions seek medical treatment for them. Treatment can involve the use of antispasmotic medications as well as the down-training (conscious involvement and relaxation of previously unconscious muscle movements) so that spasms occur less frequently or not at all.

Proctitis is an inflammation of the anus and the lining of the rectum, affecting only the last 6 inches of the rectum.

Bleeding of the lower GI tract will typically appear as hematochezia and can vary in degree of seriousness. Slow bleeding from the ascending portion of the colon can result in partial digestion of the blood and the appearance of melena in the stool.

One of the most common causes of rectal pain is an anal fissure. It involves a tear in the anal canal probably due to trauma from defecation and are usually treated effectively with sitz baths, stool softeners, and analgesics.

The symptoms of this condition include:

- An upper respiratory tract infection may precede all other symptoms in as many as 69% of patients.

- A single, 2- to (rarely) 10-cm oval red "herald" patch appears, classically on the abdomen. Occasionally, the "herald" patch may occur in a 'hidden' position (in the armpit, for example) and not be noticed immediately. The "herald" patch may also appear as a cluster of smaller oval spots, and be mistaken for acne. Rarely, it does not become present at all.

- 7–14 days after the herald patch, many small (5–10 mm) patches of pink or red, flaky, oval-shaped rash appear on the torso. The more numerous oval patches generally spread widely across the chest first, following the rib-line in a characteristic "christmas-tree" distribution. Small, circular patches may appear on the back and neck several days later.

- In 6% of cases an "inverse" distribution may occur, with rash mostly on the extremities. In children, presentation can be atypical or inverse, and the course is typically milder.

- About one in four people with PR have mild to severe symptomatic itching. (Moderate itching due to skin over-dryness is much more common, especially if soap is used to cleanse the affected areas.) The itching is often non-specific, and worsens if scratched. This tends to fade as the rash develops and does not usually last through the entire course of the disease.

- The rash may be accompanied by low-grade fever, headache, nausea and fatigue.