Merck Manual

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Anal Fissure

(Fissure in Ano; Anal Ulcer)

By

Parswa Ansari

, MD, Hofstra Northwell-Lenox Hill Hospital, New York

Full review/revision Jan 2023
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An anal fissure is a tear or ulcer in the lining of the anus (the opening at the end of the digestive tract where stool leaves the body).

  • Anal fissures may occur after passage of hard or large bowel movements.

  • Symptoms include pain or bleeding during or after a bowel movement.

  • The diagnosis is based on an examination of the anus.

  • Treatment includes stool softeners, protective ointments, and sitz baths and sometimes botulinum toxin injection or a surgical procedure.

Anal fissures may be caused by an injury from a hard or large bowel movement or from frequent loose bowel movements. Rarely, they may also be caused by penetration of the anus during anal sex.

Fissures cause the anal sphincter (the muscular ring that keeps the anus closed) to go into spasm, which worsens pain and prevents healing.

Anal fissures can occur in people of any age but are most common among infants.

Symptoms of Anal Fissure

Fissures cause pain and bleeding, usually during or shortly after a bowel movement. The pain lasts for several minutes to several hours and then subsides until the next bowel movement.

Diagnosis of Anal Fissure

  • A doctor's examination

A doctor diagnoses a fissure by gently inspecting the anus.

Treatment of Anal Fissure

  • Stool softeners and fiber

  • Protective ointments and sitz baths

  • Botulinum toxin injection or nitroglycerin ointment or calcium channel blockers

A stool softener and fiber supplements or increased dietary fiber may reduce the possibility of injury by hard or large bowel movements.

Healing is aided by using zinc oxide ointments or glycerin suppositories that lubricate the lower rectum and soften stool.

Applying topical anesthetics (such as benzocaine or lidocaine) to the anus or soaking in a warm (not hot) sitz bath for 10 to 15 minutes after each bowel movement eases discomfort and helps increase blood flow, which promotes healing. The soaking is accomplished by squatting or sitting in a partially filled tub or using a container filled with warm water placed on the toilet bowl or commode.

To reduce anal sphincter spasms and promote healing of fissures, doctors may inject the anal sphincter with botulinum toxin or have the person apply nitroglycerin ointment or calcium channel blockers (such as nifedipine cream or diltiazem gel) to the area of the fissure.

If these measures do not work, surgery may be needed. To relieve sphincter spasms, doctors cut a portion of the internal sphincter (called internal anal sphincterotomy).

Drugs Mentioned In This Article

Generic Name Select Brand Names
Aquaphor 3 IN 1 Diaper Rash, Aquaphor Baby Fast Relief Diaper Rash, Aquaphor Fast Relief Diaper Rash, Balmex, Boudreaux Butt Paste, Boudreauxs Rask, Carlesta, Coppertone, COZIMA, Desitin, Desitin Maximum Strength, Desitin Rapid Relief, Diaper Rash , Dr. Smith Adult Barrier, Dr. Smith's, Dr. Smith's Diaper Rash, Dr. Smith's Rash + Skin, DynaShield, Eucerin Baby Sunscreen Sensitive Mineral , Eucerin Sunscreen Sensitive Mineral, Flanders Buttocks , Medi-Paste, Novana Protect, Triple Paste, Triple Paste Adult Incontinence, Z-Bum
Colace Glycerin, Fleet, Fleet Pedia-Lax, HydroGel, Introl , Lubrin, Orajel Dry Mouth, Osmoglyn, Sani-Supp
Advocate Pain Relief Stick, Americaine, Anbesol, Anbesol Baby , Anbesol Jr , Banadyne-3, Benzodent, Benz-O-Sthetic, Boil-Ease, Cepacol Sensations, Chloraseptic, Comfort Caine , Dry Socket Remedy, Freez Eez, Little Remedies for Teethers, Monistat Care, Orabase, Orajel, Orajel Baby, Orajel Denture Plus, Orajel Maximum Strength, Orajel P.M., Orajel Protective, Orajel Severe Pain, Orajel Swabs, Orajel Ultra, Oral Pain Relief , Oticaine , Otocain, Outgro, Pinnacaine, Pro-Caine, RE Benzotic, Topex, Topicale Xtra, Zilactin-B
7T Lido, Akten , ALOCANE, ANASTIA, AneCream, Anestacon, Aspercreme, Aspercreme with Lidocaine, Astero , BenGay, Blue Tube, Blue-Emu, CidalEaze, DermacinRx Lidogel, DermacinRx Lidorex, DERMALID, Ela-Max, GEN7T, Glydo, LidaMantle, Lidocare, Lidoderm, LidoDose, LidoDose Pediatric, Lidofore, LidoHeal-90, LIDO-K , Lidomar , Lidomark, LidoReal-30, LidoRx, Lidosense 4 , Lidosense 5, LIDO-SORB, Lidotral, Lidovix L, LIDOZION, Lidozo, LMX 4, LMX 4 with Tegaderm, LMX 5, LTA, Lydexa, Moxicaine, Numbonex, ReadySharp Lidocaine, RectaSmoothe, RectiCare, Salonpas Lidocaine, Senatec, Solarcaine, SUN BURNT PLUS, Tranzarel, Xylocaine, Xylocaine Dental, Xylocaine in Dextrose, Xylocaine MPF, Xylocaine Topical, Xylocaine Topical Jelly, Xylocaine Topical Solution, Xylocaine Viscous, Zilactin-L, Zingo, Zionodi, ZTlido
Deponit, GONITRO , Minitran, Nitrek, Nitro Bid, Nitrodisc, Nitro-Dur, Nitrogard , Nitrol, Nitrolingual, NitroMist , Nitronal, Nitroquick, Nitrostat, Nitrotab, Nitro-Time, RECTIV, Transdermal-NTG, Tridil
Adalat, Adalat CC, Afeditab CR, Nifediac CC, Nifedical XL, Procardia, Procardia XL
Cardizem, Cardizem CD, Cardizem LA, Cardizem SR, Cartia XT , Dilacor XR, Dilt-CD , Diltia XT, Diltzac, Matzim LA, Taztia XT, TIADYLT ER, Tiamate, Tiazac
NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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