How to Heal a Split Bum Crack: Causes and Treatments

A split or crack in the skin of the gluteal cleft, the fold running between the buttocks, usually heals within one to two weeks once you remove the cause and keep the area clean and dry. The trouble is that the gluteal cleft is one of the hardest places on the body to heal: it stays warm, traps moisture, and the skin surfaces rub together with every step. That combination means the same split can reopen repeatedly unless you address what started it and change the local environment while the skin repairs itself.

Why the Skin Splits There in the First Place

Skin in the gluteal cleft is thinner than on most of the body, and it lives in conditions that work against it. Warmth and sweat create a humid microenvironment, while walking, sitting, and bending produce constant friction between the two skin surfaces. Intertrigo, the general term for inflammation where skin folds press together, is driven by exactly these mechanical and environmental factors, and the gluteal cleft is one of its favorite locations.¹ Once moisture softens the outer skin layer, even normal movement can create a shallow split or raw patch that stings every time you sit down.

Humidity makes friction worse. When skin is damp, its coefficient of friction against fabrics rises, which increases the mechanical stress on the skin surface and the tissue underneath.² This is why people who sweat heavily, wear non-breathable underwear, or sit for long hours are especially prone to gluteal cleft splits. It is also why the problem tends to flare in summer or after exercise.

The Wet Wipe Problem

If you use wet wipes or moist toilet paper, they may actually be causing or worsening the split. A preservative commonly found in these products, methylchloroisothiazolinone/methylisothiazolinone, is one of the most frequent causes of allergic contact dermatitis in the perianal and buttock area.³ The resulting rash looks like eczema: red, cracked, sometimes weeping skin that refuses to heal despite creams and antibiotics.

This is not a rare sensitivity. One case series documented six children with chronic buttock and perianal dermatitis that had resisted repeated courses of antibiotics and prescription steroid creams. All of them tested positive for allergy to the preservative in their wet wipes, and all of them cleared up completely once they stopped using the wipes.⁴ Adults are equally susceptible. Moist toilet paper can also contain other documented allergens including fragrances and additional preservatives.⁵

If your split has been lingering for weeks despite everything you have tried, and you use wet wipes or moist toilet paper, the simplest first step is to stop using them entirely. Switch to plain dry toilet paper, or use plain water on a soft cloth. Many people see dramatic improvement within days.

When the Split Is Actually an Anal Fissure

Not every split in this area is a surface skin crack. If the pain is concentrated at the anus itself, especially during and after bowel movements, you may be dealing with an anal fissure rather than a friction or moisture issue. An anal fissure is a small tear in the lining of the anal canal, and it has its own set of causes: mechanical trauma from passing hard stool, spasm of the internal sphincter muscle, and reduced blood flow to the area.⁶

The vicious cycle with fissures is that the tear triggers sphincter spasm, which reduces blood supply to the wound, which prevents healing, which maintains the tear. Research has shown that people with fissures tend to have significantly higher resting anal pressure than people without them, and that this elevated pressure is driven by abnormal internal sphincter activity.⁷ Breaking that cycle is the key to healing.

The hallmark of an anal fissure is sharp pain during a bowel movement, sometimes with a small amount of bright red blood on the paper. The pain can persist for minutes to hours afterward. If that matches your experience, the treatments described below for fissures will be more relevant than the moisture and barrier strategies that work for surface skin splits.

First-Line Treatments for Surface Skin Splits

For a crack caused by moisture, friction, or mild irritation, the goal is straightforward: dry the area, reduce friction, and protect the healing skin.

Keep it dry: After showering, pat the area gently with a soft towel or use a hair dryer on a cool setting. Moisture is the enemy of healing in skin folds, so spend the extra minute getting the crease fully dry before putting on clothes.
Zinc oxide barrier cream: A plain zinc oxide cream or paste creates a physical barrier that shields the raw skin from moisture and friction. Zinc oxide has also been shown to speed up the regrowth of skin over superficial wounds and reduce inflammation in the process.⁸ Apply a thin layer after cleaning and drying. Diaper rash creams, which are mostly zinc oxide, work well and are inexpensive.
Breathable underwear: Cotton or moisture-wicking athletic fabrics allow airflow. Tight synthetic underwear traps heat and sweat against the cleft. Looser-fitting bottoms help too, especially while the split is healing.
Avoid irritants: No scented soaps, no wet wipes, no harsh body washes on the area. Plain water or a gentle, fragrance-free cleanser is all you need.

For most surface splits, this combination resolves the problem in about a week. If the crack is deeper or repeatedly reopening, applying a thin strip of medical-grade skin protectant or even a small piece of non-stick gauze between the buttocks can reduce the skin-on-skin contact that prevents healing.

Treatments Specific to Anal Fissures

Acute anal fissures, those lasting less than about six weeks, often respond well to conservative measures: warm sitz baths several times a day, fiber supplementation to soften stool, and adequate water intake. Fiber supplements such as psyllium have been shown to improve stool consistency and reduce the mechanical trauma that caused the tear in the first place.⁹ The sitz bath relaxes the sphincter temporarily, improving blood flow to the wound.

When conservative measures are not enough and a fissure becomes chronic, prescription topical ointments can help break the spasm-ischemia cycle. Topical diltiazem, a calcium channel blocker applied as an ointment, healed fissures in about three-quarters of patients within two to three months in one study, and additional treatment brought the total healing rate even higher.¹⁰ Glyceryl trinitrate (GTN) ointment works through a different mechanism, relaxing the sphincter via nitric oxide, and produces similar healing rates. A head-to-head trial found the two were equally effective, though diltiazem caused fewer side effects, particularly the headaches that are common with GTN.¹¹

Botox Injections and Surgery for Stubborn Fissures

For fissures that do not respond to topical treatment, injecting botulinum toxin directly into the internal sphincter muscle is the next step. The toxin temporarily paralyzes part of the muscle, lowering the spasm and allowing blood flow to return to the wound. Healing rates with botulinum toxin injections reach roughly 60 to 85 percent, without the headaches associated with GTN ointment.¹²

Lateral internal sphincterotomy, a minor surgical procedure that cuts a small portion of the internal sphincter, is the most effective treatment available, with healing rates around 90 to 95 percent. The tradeoff is a real risk of some degree of fecal incontinence afterward, estimated at roughly 5 to 15 percent of cases.¹² Botulinum toxin carries a lower incontinence risk than surgery, which is why most clinicians try it first.¹³ The decision between botulinum toxin and surgery usually comes down to how much the fissure has already resisted treatment, the patient’s baseline continence, and personal preference about trading a higher cure rate for a small but meaningful incontinence risk.

Inverse Psoriasis and Other Skin Conditions That Mimic Simple Splits

Sometimes what looks like a simple moisture crack turns out to be a skin condition that requires different treatment entirely. Inverse psoriasis is a variant of psoriasis that targets skin folds, including the gluteal cleft, and it can be hard to distinguish from intertrigo, fungal infections, or contact dermatitis. Unlike the scaly plaques people associate with psoriasis, inverse psoriasis tends to produce smooth, red, raw-looking patches because the moisture in the folds prevents the typical scaling.¹⁴

Treatment for inverse psoriasis ranges from mild topical steroids and calcineurin inhibitors to systemic medications in severe cases. Vitamin D analogs applied topically are another option. The key point is that if your split keeps coming back despite good hygiene and barrier creams, and it looks more like a persistent red patch than a clean linear crack, a dermatologist can help sort out whether you are dealing with psoriasis, a fungal infection, or something else. Patch testing can also identify whether contact allergy is playing a role.

Prolonged Sitting and Pressure

If you spend long hours sitting, either for work or because of limited mobility, the skin in the gluteal cleft is under extra stress. Sitting compresses the soft tissue between the bone and the chair surface, and for people with reduced mobility the mechanical loads on the gluteal tissue are substantially higher than in people who shift position frequently. Research comparing paraplegic patients with healthy controls found that the strains and stresses in the buttock tissues were significantly elevated during sitting, and that simply switching from sitting to lying reduced peak compression and shear stresses by as much as 70 percent.¹⁵

You do not need to be paraplegic for this to matter. Anyone who sits for eight or more hours a day, truck drivers, office workers, wheelchair users, is putting sustained mechanical stress on this skin. Taking regular standing breaks, using a pressure-relieving cushion, and keeping the area dry all help prevent the kind of maceration and tissue breakdown that leads to chronic splitting. If you already have a split, reducing sitting time as much as possible during the healing period makes a real difference.

When to See a Doctor

Most gluteal cleft splits are nuisances, not emergencies. But there are situations where professional evaluation matters:

No healing after two weeks: A simple skin crack with good care should show clear improvement in that window. Persistent splitting suggests an underlying condition like psoriasis, a fungal infection, or contact allergy that needs targeted treatment.
Pus, spreading redness, or fever: These are signs of secondary infection. A cracked skin surface is an open door for bacteria, and the warm, moist environment of the gluteal cleft is hospitable to them.
Recurrent anal fissures: If you keep getting fissures despite adequate fiber intake and soft stools, a gastroenterologist should evaluate for underlying conditions. Crohn’s disease, for example, can produce fissures, ulcers, and skin tags in the perianal area as part of its broader inflammatory process.¹⁶
Lumps or swelling in the cleft: A case series examining gluteal cleft pathologies found a surprising range of diagnoses beyond the expected skin conditions, including neurological cysts and inflammatory bowel disease.¹⁷ A lump that does not resolve, or a pit or sinus tract in the cleft, warrants evaluation to rule out pilonidal disease or other conditions.

Preventing Recurrence

Once you have healed a gluteal cleft split, prevention is mostly about maintaining the conditions that allowed healing. Keep the area dry after bathing and exercise. Use breathable fabrics. If you are prone to sweating, a light dusting of plain cornstarch or a moisture-wicking body powder after showering can help absorb excess humidity before it softens the skin. Avoid fragranced products in the area.

For people prone to anal fissures, the long game is stool management. Enough fiber and water to keep stools soft and easy to pass eliminates the main mechanical trigger. Psyllium husk is inexpensive and well-studied for this purpose.⁹ Starting with a small dose and increasing gradually helps avoid the bloating that puts people off fiber supplements. If constipation is chronic, an osmotic laxative like polyethylene glycol can be added.

Weight loss, where relevant, reduces the depth of the gluteal cleft and the amount of skin-on-skin contact, which lowers moisture trapping and friction. Exercise improves circulation to the area, which supports skin integrity, though it is worth showering or at least drying the cleft soon after a workout rather than sitting in sweaty clothes. Small habits, keeping the area dry, wearing the right fabric, and avoiding chemical irritants, compound over time and can turn a recurring problem into a one-time event.

1
PubMed Central. Recurrent candidal intertrigo: challenges and solutions
2
PubMed Central. Effects of humidity on skin friction against medical textiles as related to prevention of pressure injuries
3
PubMed. Patch testing in patients with perianal eczema
4
PubMed. Six children with allergic contact dermatitis to methylisothiazolinone in wet wipes (baby wipes)
5
JAMA Dermatology. The Hazards of Moist Toilet Paper: Allergy to the Preservative Methylchloroisothiazolinone/Methylisothiazolinone
6
Journal of Visceral Surgery. Review Update on the management of anal fissure
7
PubMed. The internal sphincter and anal fissure
8
PubMed Central. Topical Zinc Oxide Assessed in Two Human Wound-healing Models
9
PubMed. Dietary fibre supplementation with psyllium or gum arabic reduced incontinent stools and improved stool consistency in community living adults
10
PubMed. Topical diltiazem ointment in the treatment of chronic anal fissure
11
PubMed. A prospective randomized trial of diltiazem and glyceryltrinitrate ointment in the treatment of chronic anal fissure
12
PubMed Central. Efficacy of botulinum toxin in the treatment of chronic anal fissure: a comprehensive systematic review
13
PubMed Central. Incidence of anal incontinence among patients with anal fissure treated with Botox injection versus lateral sphincterotomy
14
PubMed Central. Inverse Psoriasis: From Diagnosis to Current Treatment Options
15
PubMed. Strains and stresses in sub-dermal tissues of the buttocks are greater in paraplegics than in healthy during sitting
16
PubMed Central. Nonfistulizing Perianal Crohn’s Disease
17
PubMed Central. Adolescent Gluteal Cleft Pathologies Not Due to Pilonidal Disease: A Case Series and Diagnostic Algorithm