The patient is a 45-year-old female who presents to your office with the complaint of perianal itching. The assessment of the complaint of pruritus ani begins with a thorough history. The eventual successful treatment of the condition will be facilitated by carefully listening to the patient at the initial visit to investigate his or her symptomology. When did the condition arise? Patients with pruritus ani due to a dermatosis or neoplasia often experience symptoms for longer than those with idiopathic pruritus ani [8]. How often does the patient feel the perianal itching? Is it constantly present or does it ultimately subside? The precipitating and/or exacerbating factors—especially the initial inciting event—for pruritus should be explored. In general, perianal itching usually develops following a bowel movement, particularly if it has a liquid consistency, or at bedtime [12]. Does the itching wake the patient from sleep? Is the area being traumatized: Does the patient scratch or vigorously rub the perianal skin? Alternatively, does the patient engage in perianal grooming—by waxing, shaving, or depilatory—that may damage the skin? Does the perianal skin seem moist or sweaty or is there drainage noted? Do any members of the same household have a similar complaint of perianal itching, suggestive of an infectious etiology such as pinworms? Prior and current prescription and over-the-counter medications, especially used by the patient for the treatment of the condition, should be reviewed. The bowel habits—the stool frequency and consistency—and the perianal cleansing methods of the patient should be elucidated. Has the patient added or changed any cleansing products such as soap, detergent, toilet paper, or wet wipes recently? The patient should be questioned about the presence of rectal bleeding. Such bleeding, however, may emanate from fissuring or excoriation of the perianal skin. Other alarm symptoms—such as unintentional weight loss, melanotic stools, unusual fatigue, and changes in bowel habits or stool caliber—should be sought. Is there itching or a rash elsewhere on the patient’s skin surface that might point to a dermatologic condition? Any recent illnesses and their treatment, particularly with antibiotics and steroids, should be explored. As part of the inquiries regarding the medical history, the patient should be asked about skin diseases, allergies, atopy, urticaria, and previous skin patch testing that might signal a contact dermatitis [2]. Systemic diseases such as diabetes mellitus, liver disease, renal failure, hyperthyroidism, iron-deficiency anemia, leukemia, and lymphoma may be associated with pruritus ani, although the itching usually is more generalized; diabetic patients have a greater propensity to infection and to low resting sphincter pressures [13]. In females, details of previous child bearing should be elicited. The patient should be surveyed about previous sexually transmitted diseases and anoreceptive intercourse; MacLean and Russell comment that latex condoms or lubricant may produce a contact dermatitis [13]. Has the patient underwent previous anorectal procedures that may have altered the anal morphology or weakened the anal sphincters? Mazier emphasizes the importance of a dietary history, particularly focusing on caffeine, chocolate, citrus products, and tomatoes and tomato products [12]. The patient should be asked about fluid intake, which, if excessive, could lead to liquid stools as well as about laxative use [11, 14]. Mazier also advises that a social history be obtained to identify familial, work, and financial stressors that may contribute to pruritus ani [12]. Twenty percent of the patients with pruritus ani in the series from Smith and colleagues observed that stress worsened their symptoms [9]. Pruritus ani has also been cited as a manifestation of a psychiatric disorder. However, Dasan et al. identified only 13.5 % of their patients with pruritus ani who scored above the threshold of 7/8 on a general health questionnaire (GHQ 28) inquiring about psychiatric issues [15]. Also, there were no statistically significant deviations from the validity scales noted on the Minnesota Multiphasic Personality Inventory in the study from Smith and colleagues [9]. The family history should be directed to inflammatory bowel diseases, gastrointestinal malignancies, and skin disorders [13].

A general physical examination should be performed. In addition, the presence of a dermatologic condition should be assessed by examining the entire skin surface of the disrobed patient, particularly the flexor and extensor surfaces of the limbs, the inguinal creases, scalp, and the interdigital toe spaces. The classic findings of various dermatologic diseases often are not exhibited in the perianal area; the diagnosis thus may be better determined based upon skin lesions elsewhere on the body [11]. If a dermatosis is identified, a referral to a dermatologist should be considered. Dasan and colleagues suggest that, based upon the high incidence of a dermatosis as the cause of pruritus ani in their combined colorectal-dermatological clinic—85 %—a dermatologist should actually be the first referral [15]. Also a patient with a significant dermatosis might benefit from the input of a wound ostomy nurse. Enlargement of the inguinal lymph nodes may indicate neoplasia or a sexually transmitted disease [2].

The perianal skin is included in the physical examination. In some patients, there may be no evident abnormalities, although most will have an associated dermatosis [5]. Daniel et al. offered descriptions of the various stages of the perianal skin changes [8] (Table 7.2). The degree of the perianal skin changes often are correlated with the intensity and duration of pruritus ani [12]. Perianal erythema may be noted in mild cases of pruritus ani [12] (Fig. 7.5). A brightly hued erythema may signal a fungal infection [2]. More severe or chronic perianal itching may produce lichenification—a nonspecific whitening and thickening of the skin with pronounced skin folds—or fissuring, in which cracks appear in the skin [12]. Chronic inflammation is frequently associated with hyperpigmentation [2] (Fig. 7.3). Excoriation indicates that the patient has been scratching or vigorously rubbing the perianal skin. A skin lesion with a distinct margin may point to psoriasis, tinea, or a neoplasm [2]. Multiple perianal vesicles are consistent with herpes [2]. A dermatitis with an indistinct border is more commonly seen with idiopathic pruritus ani [2]. Significant inflammation may lead to “weeping” of the perianal skin or maceration. In addition to the perianal region, pruritus may ultimately include the buttocks and genital area, both of which should also be examined [12] (Fig. 7.4). A Corynebacterium minutissimum cutaneous infection—erythrasma—is characterized by the fluorescence of the perianal skin under Wood’s light.

The digital rectal examination (DRE) and anoscopy/rigid proctoscopy are performed to identify any anorectal sources for pruritus ani. In particular, the patient should be assessed for internal hemorrhoidal disease, anal fistula, anal fissure, and anal neoplasia. Straining during the anoscopy may disclose hemorrhoidal or mucosal prolapse. The anal sphincters should be assessed with anal manometry and endoanal ultrasound if the patient reports fecal soilage. A flexible sigmoidoscopy or colonoscopy may be considered based upon the patient’s associated symptoms, age, and personal or family history of colon and rectal cancer and adenomatous polyps. Daniel et al. urge that a colonoscopy be performed particularly in patients older than 50 years old with long-standing pruritus ani due to a significantly higher risk of colon and anorectal cancer [8]. A vaginal examination may be indicated in certain patients if vaginal drainage appears to be the source of the perianal pruritus.

The inclusion of additional investigations should be guided by the patient’s symptomology and physical findings. Markell and Billingham comment that, as a majority of patients are diagnosed with idiopathic pruritus ani, in the absence of specific findings at the initial evaluation, the exclusion of secondary causes of pruritus ani may be instituted if a 4–8-week trial of generic management is unsuccessful [11]. Alarm symptoms that may instigate further evaluation include rectal bleeding, melanotic stools, a change in bowel habits or stool caliber, malaise, unusual fatigue, and unintentional weight loss. A perianal mass and significant skin changes/dermatosis also signal an etiology other than idiopathic pruritus ani. Among the blood work that may add to the diagnostic process are a complete blood count, immunoglobulin E, blood glucose, celiac screen, renal and liver function panels, and syphilis serology [13]. Skin patch testing by an allergist should be considered, particularly if a contact dermatitis is suspected [2].

A skin biopsy should be obtained if a suspicious lesion is noted or if conservative measures are not successful. A 3–6 mm punch biopsy may be used. Both the affected skin—the most abnormal site—and the adjacent normal-appearing skin should be biopsied [2, 13]. In the absence of such a finding, a skin biopsy for patients with idiopathic pruritus ani usually demonstrates normal skin or nonspecific changes consistent with chronic inflammation, fibrosis, and skin hypertrophy [12, 16].

The presence of an infectious process may be investigated. However, due to difficulties with specimen collection and transportation, such testing is often plagued by a high false-negative rate [2]. The swabs should be obtained prior to the digital rectal examination, as the lubricant contains a bactericide [2]. The appropriate medium and storage temperature should be used [2]. The more common bacteria infecting the perianal skin include the Streptococcus species , Staphylococcus species , and Corynebacterium minutissimum . A rapid streptococcus test can diagnose streptococcal dermatitis. A fungal infection may also be identified via skin scrapings [2]. The exudate from unroofed vesicles such as found with an active herpes simplex infection may be sent to the microbiology laboratory on a slide or in a viral culture medium [2]. Testing for Neisseria gonorrhoeae and Chlamydia trachomatis may be performed by polymerase chain reaction (PCR) swabs in high-risk individuals [13].

The patient is a 41-year-old male with no significant medical history who presents to your office with the complaint of perianal itching, occurring 30 min after a bowel movement, for the past 6 weeks. He also makes note of spots of bright red blood on the toilet paper when wiping following a bowel movement. Wiping the perianum when the itching arises results in symptomatic relief. He has approximately four loose bowel movements per day. The patient has attempted no treatment other than more vigorous cleansing. A thorough evaluation identifies no perianal or anorectal pathology as a cause of his symptoms. The perianal skin demonstrates mild circumferential erythema and minimal excoriation. He is given the diagnosis of idiopathic pruritus ani.

The majority of patients with the complaint of perianal itching, as with this patient, will be ultimately categorized with idiopathic pruritus ani. Few studies have explored the underlying cause of idiopathic pruritus ani. One hypothesis suggests that the “self-sterilizing” function of the perianal skin is impaired [17]. Smith and colleagues note that the consistency of the stool also impacts the perianal itching: 48 % of patients with this condition reported loose or watery stools [18]. Certain foods or medications may add to the loose stool consistency. In contrast, the fecal microflora has not been shown to contribute to itching: Silverman et al. determined that there is no significant difference in the microbiology of stool from patients with and without pruritus ani [19]. Moreover, Caplan found no association between the stool pH and perianal itching [20].

Fecal soiling has also been suggested as a culprit for provoking or perpetuating perianal itching. Although the fecal soiling may be obvious, as with patients suffering from gross fecal incontinence, in others, as with this patient, it may be imperceptible yet sufficient to incite itching [2]. In a study from Smith and colleagues, 41 % of patients with pruritus ani experienced fecal incontinence daily to three times per week; 33 % of this group reported the episode within 1 h of the bowel movement [9]. Caplan also pointed to cutaneous secretions and other rectal discharges as factors in precipitating or promoting perianal itching [20]. The soiling may be a consequence of poor perianal hygiene, particularly in patients with obesity, deep buttocks, hirsutism, or pronounced perianal skin folds; incomplete rectal emptying; altered postsurgical anal or rectal morphology; anorectal disease such as internal hemorrhoidal disease or fistula in ano; an irregular stool consistency and/or frequency; and/or abnormal sphincter function or reflexes [2, 13, 21]. Thirty-nine percent of the patients with pruritus ani in the series from Smith et al. complained of a sensation of incomplete emptying [9]. Inciting the rectoanal inhibitory reflex (RAIR) resulted in a significantly more pronounced percentage decline in the anal pressures of patients with idiopathic pruritus ani than of controls (57 vs 40 %, p < 0.05), despite normal resting and squeeze pressures, in the study from Allan and colleagues [22]. Moreover, Eyers and Thomson showed that patients with idiopathic pruritus ani demonstrated a significantly more exaggerated RAIR in response to rectal distention with 50, 100, and 150 mL of air than patients with pruritus due to anal disease (p < 0.01, p < 0.01, and p < 0.001, respectively) [23]. Farouk et al. identified a significantly greater degree (p < 0.01) and duration (p < 0.001) of transient internal anal sphincter relaxation in patients with idiopathic pruritus ani as compared to controls during ambulatory anal manometry; at the same time, the symptomatic patients generated a more significant increase in rectal pressure than the control group (p < 0.01) [24]. In the same study, fourteen (61 %) of the patients with idiopathic pruritus ani reported staining of their underwear within 30 min of an episode of transient internal anal sphincter relaxation, while 17 (74 %) and 23 (100 %) noted perianal itching within 1 and 2 h, respectively [24]. A saline infusion test detected leakage at a significantly lower volume in patients with idiopathic pruritus ani than in controls (600 vs 1300 mL, p < 0.001); patients with more severe symptoms exhibited leakage at significantly lower volumes than those with milder complaints (p < 0.02) [22].

The perianal skin , in particular, is sensitive to the presence of fecal material. Fecal material, mucus drainage, and moisture in the perianal area impair the normal barrier function of the bilayered stratum corneum and alter the pH (normally 5.0 to 5.9) of its protective acid mantle, permitting disruption of the epithelium—particularly in the presence of friction from apposing surfaces or of fragile aging skin—and entry of irritants and colonizing microorganisms such as the Candida species into the dermis [25, 26]. Consequentially, an inflammatory reaction is incited, provoking further itching [27]. In a seminal 1966 study, Caplan explored the effect of feces upon the skin, performing patch testing on the perianal skin and on the arms of 27 healthy male subjects, using their own feces, and on 10 healthy males as controls [20]. The inner arms of each subject were treated with fresh moist feces, feces with a pH of 5.0 and of 8.0, a control solution with a pH of 5.0 and of 8.0, and a plain piece of gauze [20]. Twelve of the 27 study patients (44 %)—only four of whom had previous histories of perianal itching—reported perianal irritation, itching, or burning following the application of the feces to the perianal skin, with the symptoms occurring either immediately (n = 1), within 1 h (n = 7), or at 3, 4, 6, or 24 h; the control subjects were free of pruritic symptoms. While two test subjects noted that pruritic symptoms persisted for 1 h but then resolved spontaneously, the remaining ten patients suffered the symptoms for 15 min to 6 h, with relief only obtained immediately after removing the feces. There were no objective findings when examining the perianal skin. In contrast, none of the inner arm patch tests precipitated pruritic symptoms, although mild skin reactions were observed in some subjects [20]. The author concluded that fecal matter produces an irritant, not an allergic effect [20]. Moreover, the perianal skin is more susceptible to the irritant nature of feces than is skin elsewhere on the body [20]. The fecal components that may serve as irritants include bacterial endopeptidases such as trypsin and kinase and exotoxins as well as intestinal lysozymes [19, 23, 28, 29].

The treatment of idiopathic pruritus ani begins with conservative measures: the removal of irritants and the control of itching (Table 7.3). These recommendations should be reviewed in great detail with the patient in order to ensure better compliance. The perianal skin should neither be scratched nor vigorously rubbed, even in the course of cleansing after a bowel movement. In the event that the patient scratches the area unconsciously while sleeping, socks or mittens may be worn over the hands. The fingernails should be kept short [2]. Scratching traumatizes the perianal skin, exacerbating the inflammatory process and enhancing itching; the resulting itch-scratch cycle becomes difficult to halt in the face of continued injury to the perianal skin [25, 30]. No soaps or cleansing creams—which dry and alkalinize the skin—should be applied to the perianal skin, even in the shower or bath [26]. In the bath tub, bubble baths and perfumed shampoos and conditioners should be eschewed. Washcloths, loofahs, and other cleansing accessories should be avoided when cleansing in the shower or bath, instead relying upon water and the patient’s hand; 65 % of the oil and dirt is effectively removed with water alone [26]. If necessary, a physician-sanctioned fragrance-free, hypoallergenic beauty bar or unscented pH neutral (pH 4–7) soap may be used [26]. Prior to leaving the bath or shower, any product residue, which may be an irritant, should be rinsed from the perianal skin [2]. Perfumed toilet paper as well as wet wipes should be replaced with gentle, unscented, undyed toilet paper [31]. The patient’s current regimen of topical medications—both by prescription and over the counter—should be stopped, as the patient could have become sensitized to the medication or one of its excipients. Perianal grooming—via waxing, shaving, or depilatory—should be stopped [13]. Moreover, detergents and fabric softeners should be substituted with fragrance-free versions [2].

The contribution of certain foods to perianal itching has been debated (Table 7.4). Specific foods may directly have an irritant effect upon the perianal skin. Tomatoes and tomato products may promote perianal pruritus via histamine release [13]. Alternatively, bowel consistency and/or frequency is altered by various foods, leading to the seepage of stool. Certain foods impact the internal anal sphincter: a decline in resting anal canal pressures was observed by Smith et al. in eight patients (73 %) 1 h following the ingestion of three cups of coffee (p = 0.03) [9, 13]. In their patients with idiopathic pruritus ani, Daniel and colleagues found that the volume of coffee significantly influenced the severity of the perianal itching (p < 0.0001); a similar correlation was not identified for alcohol or tobacco use [8]. The common foods that may be associated with pruritus ani should ideally be removed from the diet; once itching subsides, each item can be sequentially reintroduced into the diet. To track the success of the dietary changes, a symptom diary should be kept. There is a 24- to 48-h delay between eating a certain food and developing perianal itching [14]. Friend notes that the perianal itching subsided within 2 weeks due to this elimination diet, although no systematic study has verified its efficacy [2, 14]. If a certain food is determined to be a causative agent for the perianal itching, it should be avoided. Alternatively, the patient may be able to ingest it up to a threshold amount before symptoms occur: usually two to three cups of coffee, four cups of tea, and less than two cans of beer per day, in the experience of Friend [14]. As with certain foods, some medications such as laxatives, antibiotics, and colchicine may incite or aggravate pruritus ani either by producing an irritant effect upon the skin, causing fecal leakage (e.g., mineral oil), or by loosening the stool [2, 21] (Table 7.5).

The recommendations for the control of itching focus upon maintaining a clean, dry perianal skin without inflicting any trauma (Table 7.6). However, no systematic studies have proven the benefit of careful anal hygiene in treating pruritus ani, although the majority of groups advocate these methods [2]. After a bowel movement, the perianal skin should ideally be washed while in a squatting position in the shower with a shower head or with a bidet, without employing soap [2]. It is possible to install a bidet attachment to an existing toilet (called a washlet), if a bidet is not available. If neither method is practicable, then moistened, unscented toilet paper can be used. Alternatively, especially when outside the home, the site may be cleansed with mineral oil or another oil-based cleanser such as Balneol^® (Meda Consumer Healthcare, Marietta, GA) or with an aqueous cream, applied with a cotton ball. Immediate cleansing should also take place if itching arises spontaneously in the absence of a bowel movement, even at night, as it may represent the occult leakage of stool [2]. Following cleansing, the moist perianal skin should be gently patted dry, after which, if at home, the area should be further dried with a hairdryer on the cool setting. A barrier cream such as zinc oxide or Calmoseptine^® (Calmoseptine, Inc., Huntington Beach, CA) can then be applied as a skin protectant after cleansing. Siddiqui and colleagues suggest that petroleum jelly be placed on the perianal skin after washing [2]. In contrast, Rohde recommends that water—as well as ointments, creams, gels, and suppositories—not at all be applied to the perianal skin, using only a “smooth dry article” to wipe, possibly along with a few drops of oil, such as olive oil [32]. He found that the 19 patients (100 %) who exactly followed his guidelines but only 8 (33 %) who did not or partially adhered to the plan experienced a resolution of their symptoms (p < 0.001) [32].

The impact of clothing upon pruritus ani has not been studied. However, it is agreed that, since heat and moisture worsen perianal itching, clothing that promote dryness should be favored [2]. However, Smith and colleagues found an equal incidence of pruritus ani in male Navy personnel working in hot (5 %) and cool (7 %) areas on a ship [9]. Yet, most groups advocate loose, cotton clothing. Clothing to avoid include pantyhose, jeans or other tight pants, swimsuits, leotards, and Lycra clothing. Underwear—cotton, not nylon or acrylic—should be put on only after the perianal skin is dry and changed at least once a day [2, 10]. Also, patients who wear incontinence protection should avoid products with a plastic backing [26]. MacLean and Russell recommend that prolonged sitting be avoided [13]. The patient should wear a strip of cotton, dusted with unscented baby powder or cornstarch, against the perianal skin, changing it on multiple occasions throughout the day, to collect any moisture or drainage; Alexander-Williams describes the cotton strip as measuring twice as long as a 50 pence piece (60 mm) [25]. Powders both absorb moisture and reduce friction [26]. A sanitary napkin is not a replacement for a cotton strip and may in fact prove an irritant.

Treatment also involves eliminating any occult fecal soiling. To improve the consistency of watery to loose stools, the patient should concentrate on eating a diet high in fiber and avoiding overhydration. A fiber supplement may be added for further stool bulk, which may aid in completely emptying the rectum of feces. In the case of watery stools, antidiarrheal medications such as loperamide, diphenoxylate/atropine, and codeine may be considered. Rectal irrigation using lukewarm water in a 3–4 oz bulb syringe may be used immediately following a bowel movement to evacuate any residue that may later leak onto the perianal skin.

The patient should follow up in the office in 4–6 weeks to confirm that the symptoms and perianal skin changes have resolved. This treatment yields a more than 90 % success rate [11]. In contrast, Smith and colleagues encountered a 27 % rate of cure after a 2-year observation period, with the greater success in patients who suffered from pruritus ani for less than 2 years; the patients who had the complaint for greater than 2 years did improve symptomatically but had frequent recurrences [9]. Even after becoming asymptomatic, the patient should generally adhere to the precepts of maintaining a clean, dry perianal skin without inflicting any trauma [25]. The patient should be advised that recurrences of pruritus ani are commonly experienced, in which case the full regimen of treatment should be reintroduced. Daniel et al. found that, despite initial good responses to treatment in all their patients with idiopathic pruritus ani, the condition was associated with a 22 % recurrence rate within 9 months, which was twice as high as that for pruritus due to anorectal disease (p < 0.0001) [8].

The same patient returns for a 4-week follow-up visit, stating that he is significantly improved. He has been meticulously adhering to your instructions for treatment. However, he still notices mild perianal itching several times per week. The perianal excoriation has resolved, although the mild circumferential perianal erythema remains. The examination is otherwise unremarkable.

Topical medications, in conjunction with proper anal hygiene, are an important part of the treatment armamentarium for idiopathic pruritus ani. A topical steroid assists in stopping the itch-scratch cycle by reducing inflammation [9]. The majority of patients with mild to moderate symptoms and minor changes in skin morphology are successfully managed with a low-potency steroid preparation such as a 1 % hydrocortisone ointment, applied twice a day, for a short course. Some groups suggest that the 1 % hydrocortisone be alternated with a barrier cream such as zinc oxide or Calmoseptine^® (Calmoseptine, Inc., Huntington Beach, CA) every 2 weeks to minimize the side effects of the steroid. In a randomized, double-blind, placebo-controlled, crossover study, Al-Ghnaniem and colleagues treated ten patients with moderate idiopathic pruritus ani for a mean of 50.2 months topically with 1 % hydrocortisone (in white soft paraffin) and with a placebo (white soft paraffin), both for 2 weeks, with the study intervals preceded and separated by 2-week “washout” periods without any topical medication; the authors found significant improvements in the visual analog score (VAS) for perianal itching (p = 0.019) and in the eczema area and severity index (EASI, p < 0.01) with the steroid [5]. The dermatology life quality index (DLQI) did not significantly change (p = 0.065), possibly due to the small sample size and the minimal impact that the itching had on the patients’ lives prior to treatment [5]. In contrast, Ӧztaş and colleagues determined that Protex liquid cleanser—chosen to reduce perianal fecal contamination—applied twice daily in 32 patients with idiopathic pruritus ani for 2 weeks, yielded no statistically significant difference in symptom relief as compared to a topical steroid cream, Advantan (methylprednisolone aceponate 0.1 %), used by 28 patients: 90.6 vs 92.3 %, p > 0.05 [33]. Low-potency topical steroid preparations containing an anesthetic afford brief relief of itching; however, the perianal skin may become sensitized to the topical anesthetic, leading to a worsening of the symptoms and skin changes. There has been no recommendation made for the longest safe duration for treatment with the low-potency topical steroids [2]. A higher potency topical steroid may be necessitated by more severe symptoms or skin changes, with the course lasting for no longer than 8 weeks; if required, the high-potency steroid can then be replaced with a lower potency steroid until the symptoms and skin changes completely resolve [2]. Ultimately, once the symptoms resolve, only a barrier cream should be used on the perianal skin, employing the topical steroid for brief, as needed treatment [5]. There is no role for oral steroids for idiopathic pruritus ani. Steroid injections have been described for this condition. Tunuguntla and Sullivan presented a case study in which a 48-year-old female with intermittent rectal pain and itching was successfully treated with a single injection of 80 mg of methylprednisone acetate into the excoriated perianal skin, with no recurrence by the 1 year follow-up visit [27]. Similarly, 73.6 % of the 19 patients injected with the long-acting triamcinolone hexacetonide for perianal itching obtained “good” or “excellent” symptomatic relief in the series from Minvielle and Hernandez over a 1–9-month observation period [34].

Topical steroid preparations should be used with caution when treating idiopathic pruritus ani. Patients must be advised against prolonged use of these medications due to the association with skin atrophy. Intertriginous sites such as the perianal skin are particularly susceptible to skin atrophy [35]. The higher potency topical steroids, which are 1000-fold stronger than the lowest potency topical steroids, carry a greater risk of skin atrophy [2]. Also, as compared to steroid creams, steroid ointments are less likely to result in skin atrophy [2]. Topical steroid use may promote bacterial or fungal infections at the treatment site [33]. With chronic use, the perianal skin may appear intensely erythematous or develop telangiectasias, purpura, striae, or scar [2, 33]. Moreover, once the steroid medication is stopped, some patients suffer from a “rebound itch” (steroid addiction) that requires a gradual reduction in the dosage and concentration of the medication [2, 36].

Tacrolimus has been offered as an alternative topical medication, used off-label, for idiopathic pruritus ani. Suys conducted a randomized double-blind crossover study using topical 0.1 % tacrolimus and a placebo (petrolatum) in 21 patients with idiopathic pruritus ani [37]. Each patient was treated with the study medication and the placebo for 4-week intervals, with a 1 week washout period in between the two phases [37]. The author recorded a significant improvement in the itch intensity (p = 0.044) and frequency (p = 0.019) as a result of the treatment with topical tacrolimus; within 2 weeks of starting the medication, a 68 % symptom reduction was noted [37]. Although there was a positive trend in the DLQI during the tacrolimus treatment, it did not reach statistical significance when compared to that of the placebo phase [37]. The only reported side effect was a minimal burning sensation in one patient [37]. There was no long-term follow-up of these patients. Similarly, in a 4-week randomized study of patients with pruritus ani due to atopic dermatitis, Ucak and colleagues found that topical 0.03 % tacrolimus ointment yielded significantly improved EASI, DLQI, and itching scores as compared to placebo at weeks 4 and 6 (p < 0.05), with 12.5 % of the study subjects reporting the side effect of burning; however, 8 weeks after the conclusion of the study, recurrent symptoms were noted in 81.25 % of the tacrolimus and in 68.75 % of the placebo group [1]. Unlike the topical steroid preparations, topical tacrolimus avoids the side effect of skin atrophy. Yet this immunosuppressive medication, a calcineurin inhibitor, is associated with potential significant side effects of which the patient should be advised. Twenty percent or more of patients treated with topical tacrolimus experience burning or pruritus, flu-like symptoms, skin erythema, and headache [38]. Ali and Lyon described a 23-year-old female patient treated with 1 g of once daily 0.1 % tacrolimus applied to the perianal skin for perianal Crohn’s disease, who developed tacrolimus toxicity after 4 weeks, complaining of nausea, paresthesias, and light-headedness; tacrolimus toxicity may be accompanied by renal failure, hypertension, and gastrointestinal and central nervous system symptoms [39]. Additional rare side effects of topical tacrolimus include an increased risk of malignancy, especially lymphoma and non-melanoma skin cancer; acute renal failure; and infections with varicella-zoster, herpes simplex virus, and eczema herpeticum [38, 39]. As such, no more than the minimum amount of medication needed for symptom control should be applied to only the affected areas [38]. Systemic absorption is more likely if the topical medication is applied to injured skin [38]. Moreover, topical tacrolimus is not meant for continuous, long-term use, due to the greater risk of side effects [38]. It should be avoided if a perianal skin infection is present [38]. Also the treatment should not be employed in patients who are immunocompromised or have renal impairment [38].