Dr. Solon Gonçalves Souza Menezes
Professor of Surgery — FAMED UFU · Robotic Surgery Certification (Intuitive / Albert Einstein Hospital) · Practices at Hospital UMC and Hospital Mater Dei Santa Genoveva, Uberlândia, Brazil · +55 (34) 99341-0915
An anal fissure is a small linear tear in the skin of the anal canal, almost always in the posterior midline. It causes sharp, burning pain during bowel movements, which can last for minutes or hours, and a little bright red blood on the paper. The mechanism is a vicious circle: hard stools or diarrhea cause the tear; pain makes the internal sphincter contract excessively; the contraction reduces blood flow to the area and prevents healing. Acute fissures (less than 6 to 8 weeks) heal in about half of cases with simple measures alone; chronic fissures, with hardened edges, a skin tag and a hypertrophied papilla, rarely heal spontaneously, and that is where topical medications, botulinum toxin and surgery come in.
The guideline of the American Society of Colon and Rectal Surgeons (ASCRS 2023) is clear about the steps. First, conservative measures — fiber, water, sitz baths — for every acute fissure. Then, ointments that relax the sphincter: nitrates (effective, but with headache in at least 30% of users) or calcium channel blockers (diltiazem, nifedipine), with similar efficacy and a better side-effect profile, which is why they are preferred as first line. Botulinum toxin, injected into the sphincter, has results similar to ointments as first line and a modest gain as second line, with 5% transient incontinence. None of these treatments heals every patient: healing with topicals is around 50%.
For the chronic fissure that does not heal, lateral internal sphincterotomy is the treatment of choice, with a strong recommendation based on high-quality evidence (grade 1A in ASCRS 2023) — and the guideline accepts offering it as first line to selected patients who prefer not to go through the ointments. The operation is simple: through an incision of a few millimeters at the side of the anus, the lower portion of the internal sphincter is divided, relieving the pressure that prevents healing. In the comparative trials cited by the guideline, healing is between 88% and 100%; the meta-analysis of 8 randomized trials (1,035 patients) found healing in 90.2%, recurrence in 3.7% and some degree of incontinence — usually to gas, transient — in 8.9%. The “tailored” technique, which limits the division to the length of the fissure, keeps the healing rate with less incontinence.
And the laser? Here the answer needs to be frank, because patients arrive asking about it. Unlike hemorrhoids and fistula, there is no clinical trial, meta-analysis or guideline on laser for anal fissure: the literature comes down to case reports and small series without a comparison group, and in several of them the laser is merely the cutting instrument used to perform the sphincterotomy itself. Dr. Solon Gonçalves treats fissures following the steps of the guideline, at Hospital UMC and Hospital Mater Dei Santa Genoveva in Uberlândia, Brazil, and uses energy technology as a tool when it helps — without presenting it as an alternative to sphincterotomy, because the evidence does not yet allow it.
Book a consultationWhat to do at each stage of the fissure.
The sequence follows the ASCRS 2023 guideline. The proctological examination, done gently because of the pain, confirms the diagnosis and rules out other causes of anal wounds — Crohn's disease, infections and tumors — especially when the fissure lies off the midline.
Acute fissure
Fiber, water, mild laxatives and warm sitz baths: about half heal with this alone. Anesthetic ointments relieve pain for a limited time.
Chronic fissure — 1st line
Calcium channel blocker ointment (diltiazem or nifedipine), applied for 6 to 8 weeks; nitrates are an alternative with more headache. Healing around 50%.
Chronic fissure — 2nd line
Botulinum toxin injected into the internal sphincter, in the office or as day surgery: modest gain after ointments fail; transient incontinence in about 5%; the effect lasts a few months, during which the fissure may heal.
Refractory chronic fissure — surgery
Lateral internal sphincterotomy: healing in 88% to 100%, with 8% to 30% of some degree of incontinence in comparative studies (8.9% in the meta-analysis of randomized trials). In patients at risk of incontinence — obstetric injury, previous anal surgery —, the anocutaneous advancement flap is the sphincter-sparing alternative.
Ointment, botulinum toxin, sphincterotomy and laser, side by side.
The table summarizes what the ASCRS 2023 guideline and the meta-analyses have published for each option. The laser column has no numbers because, as of 2026, there is no comparative study to provide them.
| Aspect | Ointments (nitrate / calcium channel blocker) | Botulinum toxin | Lateral internal sphincterotomy | Laser |
|---|---|---|---|---|
| Grade of recommendation (ASCRS 2023) | 1B | 1B | 1A — treatment of choice | Not in the guideline |
| Healing | About 50% | Similar to ointments; modest gain as 2nd line | 88% to 100% (90.2% in the meta-analysis of trials) | No comparative trial; case reports and uncontrolled series |
| Recurrence | Frequent after stopping | Common after the effect wears off | 3.7% in the meta-analysis | Unknown |
| Incontinence | None | Transient in ~5% | 8.9% in the meta-analysis (usually to gas, transient); lower with the tailored technique | Unknown |
| Side effects | Headache (nitrates, ≥30%); local irritation | Pain at injection; temporary incontinence | Mild pain, bleeding, infection (rare) | Unknown |
| Where it is done | At home | Office / day surgery | Day surgery, local anesthesia with sedation or spinal | — |
On a phone, drag the table sideways to see all the columns.
What to expect before and after surgery.
Preoperative preparation
The proctological examination is done carefully, often without a digital rectal examination at the first visit because of the pain. For sphincterotomy, blood tests and an anesthetic assessment are requested; in women with a history of childbirth with perineal injury and in patients with previous anal surgery, assessment of sphincter function (sometimes with endoanal ultrasound or manometry) is important to decide between sphincterotomy and the flap. Fasting and simple bowel cleansing are advised. Botulinum toxin and ointments require no special preparation.
Recovery and postoperative care
Sphincterotomy is performed as day surgery. The pain of the fissure usually improves within the first few days, because the sphincter pressure drops; the small incision heals in one to two weeks. Sitz baths, simple painkillers and soft stools (fiber, water, mild laxative) are the basis of recovery. There may be some leakage of gas or minor soiling in the first weeks, generally transient. Work without effort is resumed in a few days. Keeping the bowels regular for life is the best prevention of recurrence.
Incontinence, recurrence and other risks, with the numbers.
The main risk of fissure surgery is a change in continence, which is why the indication is careful and the technique is economical. The numbers come from the ASCRS 2023 guideline and the meta-analysis of randomized trials.
- Incontinence after sphincterotomy — some degree (almost always to gas, transient) in 8.9% in the meta-analysis of 8 trials; the comparative studies cited by the guideline report 8% to 30% depending on the length of follow-up. The tailored technique reduces this risk (1.4% incontinence to gas in a series of 287 patients). The closed technique tends to cause less incontinence than the open one.
- Recurrence of the fissure — 3.7% after sphincterotomy in the meta-analysis; frequent after ointments and toxin when bowel habits are not corrected.
- Transient incontinence after botulinum toxin — about 5%, with recovery within weeks.
- Headache with nitrates — in at least 30% of users, leading to discontinuation in up to 20%.
- Bleeding, infection, abscess or fistula — rare after sphincterotomy.
- Laser — no comparative data published; risks not quantified.
Common questions about this procedure.
Can an anal fissure be cured?+
Yes. Acute fissures heal, in about half of cases, with fiber, water and sitz baths alone. Chronic fissures respond to ointments around 50% of the time and, when they do not heal, lateral internal sphincterotomy cures 88% to 100% of patients in the studies, with recurrence of about 4%.
What is the best ointment for a fissure? Does ointment work?+
Ointments that relax the sphincter — diltiazem or nifedipine (calcium channel blockers) and, as an alternative, nitrates — heal about half of chronic fissures in 6 to 8 weeks. Anesthetic and steroid ointments relieve pain but do not treat the cause. Use should be guided by the doctor, because nitrates cause headache in at least 30% of users.
Anal fissure: what to do to relieve the pain?+
Warm sitz baths for 10 to 15 minutes, several times a day; soft stools with fiber, water and a mild laxative; simple painkillers; and the prescribed sphincter-relaxing ointment. Avoid rough toilet paper, and do not hold back bowel movements — that worsens the cycle of pain and contraction.
Sphincterotomy or botulinum toxin (Botox)?+
Sphincterotomy heals more fissures: a meta-analysis of 18 randomized trials (1,839 patients) showed significantly higher healing with surgery. The toxin has the advantage of not cutting the muscle and of having a temporary effect, with about 5% transient incontinence, and is a good option for those at risk of incontinence or who prefer to avoid surgery — knowing that the chance of cure is lower.
Does fissure surgery cause incontinence?+
It is the main risk, which is why the indication is careful. In the meta-analysis of randomized trials, 8.9% had some degree of incontinence — almost always to gas and transient; comparative studies report 8% to 30% depending on follow-up. The tailored technique, limited to the length of the fissure, reduces this risk (1.4% in one series), and patients at increased risk — obstetric injury, previous anal surgery — are advised to have the advancement flap, which spares the sphincter.
Is there laser fissure surgery? Is it better?+
There is no evidence supporting the laser as an alternative to sphincterotomy in anal fissure: as of 2026 there is no clinical trial, meta-analysis or guideline on the subject — only case reports and small uncontrolled series, and in several of them the laser is merely the instrument used to perform the sphincterotomy itself. Promises of ‘laser fissure treatment without cutting the muscle’ have no published basis.
Does fissure surgery hurt? What is the recovery like?+
Sphincterotomy is performed as day surgery, under local anesthesia with sedation or spinal anesthesia. The pain of the fissure usually improves within the first few days, because the sphincter pressure drops. The incision is a few millimeters long and heals in one to two weeks; sitz baths and soft stools complete the recovery. Return to work takes a few days.
Does an anal fissure itch? Why does it bleed?+
The itching comes from moisture and irritation of the skin around the wound, and the bright red blood on the paper comes from the fissure itself, which tears open with each bowel movement. Heavier bleeding, with clots, or a wound off the midline require assessment, because they may indicate another disease.
Chronic fissure: when to operate?+
When the fissure persists after treatment with ointments (and, if chosen, botulinum toxin), or when the well-informed patient prefers sphincterotomy as first line — an option the ASCRS 2023 guideline accepts in selected patients without prior risk of incontinence.
How to prevent the fissure from coming back?+
By keeping stools soft and bowel habits regular, for good: fiber (25 to 30 g per day), water, physical activity and not postponing bowel movements. It is the measure that weighs most at every stage of treatment.
Do you operate through the SUS, the Brazilian public health system?+
I do operate through the SUS. I am a Professor of Surgery at the School of Medicine of the Federal University of Uberlândia and I operate on patients at the university hospital, HC-UFU. The route, however, does not go through my private practice: to be operated on through the SUS you must go to the health post or Basic Health Unit nearest your home, be assessed by a doctor and, if surgery is indicated, be placed in your municipality's regulation queue. The surgeon does not choose who gets operated on through the SUS — the queue is followed strictly, according to SUS rules.
Hospital facilities in Uberlândia, Brazil.
Hospital Mater Dei Santa Genoveva
Av. Vasconcelos Costa, 967 — Martins, Uberlândia-MG
Open in Google Maps →Content reviewed by Dr. Solon Gonçalves Souza Menezes — CRM-MG 79366, RQE 60355 (GI Surgery), RQE 44656 (General Surgery). Professor of Surgery at FAMED-UFU and Supervisor of the General Surgery Medical Residency Program at HC-UFU. ORCID. Last reviewed: October/2026.
- Davids JS, Hawkins AT, Bhama AR, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Anal Fissures. Dis Colon Rectum. 2023;66(2):190-199. doi:10.1097/DCR.0000000000002664
- Asefa Z, Awedew AF. Comparing closed versus open lateral internal sphincterotomy for management of chronic anal fissure: systematic review and meta-analysis of randomised control trials. Sci Rep. 2023;13(1):20957. doi:10.1038/s41598-023-48286-z
- Bonyad A, Zadeh RH, Asgari S, et al. Botulinum toxin injection versus lateral internal sphincterotomy for chronic anal fissure: a meta-analysis of randomized control trials. Langenbecks Arch Surg. 2024;409(1):355. doi:10.1007/s00423-024-03484-9
- Sahebally SM, Walsh SR, Mahmood W, et al. Anal advancement flap versus lateral internal sphincterotomy for chronic anal fissure — a systematic review and meta-analysis. Int J Surg. 2018;49:16-21. doi:10.1016/j.ijsu.2017.12.002
- Elfallal AH, Fathy M, Elbaz SA, et al. Comprehensive literature review of the applications of surgical laser in benign anal conditions. Lasers Med Sci. 2022;37(7):2775-2789. doi:10.1007/s10103-022-03577-1