What Causes Anal Fissures Get the Inside Scoop
Anal fissures are small tears in the anal lining, usually from hard stools or straining. Get symptoms, causes, and care options with PocketMD.
An anal fissure is a small tear in the delicate lining of your anal canal, and it usually happens when a hard or large bowel movement stretches the tissue too far. The result can be sharp pain during pooping and bright red blood on the toilet paper, which is scary but often treatable. Most fissures start with constipation, straining, or repeated diarrhea, and then a painful cycle kicks in: pain makes you tense up, which reduces blood flow and makes healing slower. In this guide you’ll learn what fissures feel like, what typically causes them, how clinicians confirm the diagnosis, and what actually helps them heal. If you want help deciding what to try next or whether your symptoms need urgent care, PocketMD can talk you through it in plain language.
Symptoms and signs of an anal fissure
Sharp pain during a bowel movement
Fissure pain is often described as a cutting or burning sensation right as stool passes. It can make you dread going to the bathroom, which sometimes leads you to hold stool in and get more constipated. That “avoidance loop” is one reason fissures can linger.
Pain that lingers after you go
Even after you’re done, the area can throb or spasm for minutes to hours because the ring of muscle there tightens up (anal sphincter spasm). When that muscle stays clenched, blood flow to the tear drops, which slows healing. Sitting can feel uncomfortable, especially on hard surfaces.
Bright red blood on paper
You might notice a streak of bright red blood on the toilet paper or on the outside of the stool. Because the tear is close to the surface, the blood is usually not mixed throughout the stool. If you see dark, tarry stool or feel lightheaded, that is a different pattern and needs prompt medical attention.
Itching or irritation at the opening
As the tear heals and reopens, the skin can get irritated and itchy, and wiping can sting. You may also notice a small amount of clear or yellowish moisture from the area, especially if the fissure has been there for a while. Gentle cleaning and protecting the skin can make a big difference in comfort.
A small skin tag or lump
With a longer-lasting fissure, you can develop a little bump at the edge called a sentinel pile (a skin tag that forms near the tear). It can make you think you have hemorrhoids, and sometimes you can have both. The key clue is that fissures usually cause intense pain with bowel movements, while hemorrhoids often cause more pressure or itching than sharp pain.
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What causes anal fissures (and who is at risk)
Hard stools and straining
The most common trigger is constipation that leads to a hard, dry, or large stool that stretches the lining until it splits. Straining also increases pressure and friction, which can worsen a tiny tear into a deeper one. If you have been “pushing through” pain to finish a bowel movement, your fissure often keeps getting re-injured.
Frequent diarrhea or wiping
Repeated loose stools can be just as rough on the tissue as constipation because the area stays inflamed and irritated. When you are wiping many times a day, the skin barrier breaks down and small cracks can form more easily. Treating the underlying diarrhea is often the missing piece when fissures keep coming back.
Childbirth and pelvic strain
Pregnancy and delivery can change bowel habits, increase constipation, and put extra strain on the pelvic floor. After delivery, pain medications and dehydration can also slow your gut, which sets up hard stools. If you are postpartum and having severe pain with bowel movements, it is worth getting checked rather than assuming it is “just hemorrhoids.”
Tight sphincter muscle and low blood flow
Some people naturally have a higher resting tone in the anal sphincter, which means the muscle stays tighter even when you are not trying to clench. That tightness reduces blood flow to the area, so a small tear has a harder time healing and can become chronic. This is why treatments that relax the muscle can be so effective even when you are already eating fiber.
Inflammatory bowel disease or infections
If fissures are off to the side rather than in the typical midline position, or if you also have ongoing diarrhea, weight loss, fevers, or mouth sores, your clinician may think about inflammatory bowel disease (Crohn’s disease) or certain infections. In those cases, the fissure is more of a signal than the whole problem. Treating the underlying inflammation is what prevents repeated tearing.
How an anal fissure is diagnosed
Your story usually gives the clue
The combination of sharp pain with bowel movements and bright red blood is often enough to strongly suggest a fissure. Your clinician will ask about constipation, diarrhea, pregnancy or recent childbirth, and any new medications that change your stool. They will also ask about symptoms that point away from a simple fissure, like black stool, unexplained weight loss, or night sweats.
A gentle exam confirms it
A careful look at the anal opening often shows the tear, although the area can be so tender that the exam has to be slow and minimal. Many clinicians avoid a deep internal exam when pain is severe because forcing it can worsen the injury. If you are anxious, it helps to say so upfront so the exam can be paced around your comfort.
When bleeding needs a broader workup
If you are over a certain age, have a family history of colon cancer, or your bleeding pattern is not typical, your clinician may recommend an evaluation of the colon. That might mean a colonoscopy or another test based on your risk. The goal is not to “over-test,” but to make sure bleeding is not being blamed on a fissure when something else is going on.
Red flags that should not wait
Get urgent care if you have heavy bleeding that soaks the toilet, feel faint, develop a fever with worsening rectal pain, or notice a painful swelling that is rapidly getting bigger. Those can point to problems like an abscess, severe infection, or significant blood loss. Also seek prompt evaluation if pain is severe and you cannot pass stool or gas, because obstruction is a different emergency.
Treatment options that actually help fissures heal
Soften stool without causing urgency
Healing usually starts with making bowel movements easier to pass, because every hard stool can reopen the tear. Many people do well with a gentle stool softener or an osmotic laxative that pulls water into the stool, but the right choice depends on whether constipation or diarrhea is your main issue. The practical goal is a soft, formed stool that passes without straining.
Warm sitz baths for spasm relief
Soaking your bottom in warm water for 10–15 minutes can relax the muscle spasm and improve blood flow, which often reduces that lingering post-bathroom pain. It also helps you clean the area without aggressive wiping. If you do this after bowel movements for a week or two, many acute fissures start to calm down.
Topical numbing and skin protection
A short course of a numbing ointment can take the edge off so you are not bracing against pain every time you go. Barrier ointments can also protect irritated skin from moisture and friction while the tear closes. Use these as support, not as the only plan, because pain control without stool changes often leads to a “same problem, quieter symptoms” situation.
Prescription creams that relax the muscle
If your fissure is not improving, clinicians often prescribe a cream that relaxes the sphincter and improves blood flow, such as nitroglycerin ointment or a calcium channel blocker cream. These can sting at first, and nitroglycerin can cause headaches, but they are aimed at the underlying spasm that keeps the tear from healing. This approach is especially helpful for fissures that have lasted more than a few weeks.
Procedures for chronic or stubborn fissures
When a fissure becomes chronic, options like botulinum toxin injections to relax the muscle or a small surgery to reduce sphincter tension (lateral internal sphincterotomy) can be considered. These are usually discussed after conservative care has been tried, because many fissures heal without procedures. If you are hearing the word “surgery,” it does not mean you failed—it often means the muscle spasm has become the main barrier to healing.
Living with an anal fissure day to day
Make bathroom time less traumatic
Give yourself time, but try not to sit and strain, because that increases pressure and swelling. A footstool to raise your knees can help your pelvic floor relax so stool passes more easily. If you feel yourself holding your breath and pushing, pause, breathe out, and try again later after water or a warm bath.
Eat for soft, predictable stools
Fiber helps, but the “best” fiber is the one you can tolerate consistently without bloating or urgency. Many people do well by adding fiber slowly and pairing it with more water, because fiber without fluid can backfire. If your fissure started after diarrhea, focus first on calming the diarrhea rather than forcing high-fiber foods that worsen it.
Protect the skin while it heals
Wiping can feel like sandpaper when the area is inflamed, so rinsing with water or using a gentle, unscented wipe can reduce irritation. Pat dry rather than rubbing, and consider a barrier ointment if moisture or itching is a problem. Small changes here can reduce daily pain a lot, even before the fissure fully closes.
Know when it’s becoming chronic
If symptoms are not clearly improving after a couple of weeks of consistent stool-softening and warm baths, you may be moving into “chronic fissure” territory. Chronic fissures often need prescription muscle-relaxing creams or a specialist plan, not just more fiber. Getting help earlier can prevent months of on-and-off pain.
Prevention and reducing recurrences
Treat constipation at the first hint
A fissure often starts with one bad bowel movement, so your best prevention is not letting constipation build for days. If travel, stress, or a new medication slows you down, respond early with extra water, gentle stool support, and a routine bathroom time. Preventing that “first hard stool” is usually easier than healing the tear afterward.
Avoid straining habits that creep in
Straining becomes a habit when you are rushing, distracted, or trying to force a bowel movement that is not ready. Try to go when you feel the natural urge, and keep your phone out of the bathroom if it makes you sit longer. Less time on the toilet usually means less pressure on the tissue.
Manage diarrhea and irritation triggers
If you get frequent loose stools from food intolerance, IBS, infections, or medications, your prevention plan has to include controlling that pattern. Ongoing diarrhea keeps the area inflamed and makes small cracks more likely to reopen. A clinician can help you sort out whether you need diet changes, medication adjustments, or testing for inflammation.
Review meds and health conditions
Some medications can constipate you, including certain pain medicines and iron supplements, while others can cause diarrhea. If you are repeatedly getting fissures, it is worth reviewing your medication list and any conditions that affect your gut. Sometimes the fix is as simple as changing timing, dose, or adding a stool plan alongside a necessary medication.
Frequently Asked Questions
How do I know if I have an anal fissure or hemorrhoids?
Fissures usually cause sharp, cutting pain during a bowel movement and often for a while afterward, while hemorrhoids more often cause pressure, itching, or painless bleeding. A fissure is a tear, so it tends to hurt when stool stretches it. If you are not sure, a gentle exam can usually tell the difference quickly.
How long does an anal fissure take to heal?
Many acute fissures improve within a couple of weeks when you keep stools soft and reduce spasm with warm baths. If symptoms persist beyond about six weeks, it may be considered chronic and often needs prescription creams or a specialist plan. The biggest predictor of healing is whether you can stop re-injuring the area with hard stools or frequent diarrhea.
Can stress cause anal fissures?
Stress does not directly tear the tissue, but it can change your bowel habits in ways that set you up for a fissure. Some people get constipated when stressed, while others get diarrhea, and both patterns can irritate the anal lining. If you notice a stress-bowel connection, building a simple stool routine can be surprisingly protective.
When should I worry about rectal bleeding with a fissure?
Small streaks of bright red blood with sharp pain are common with fissures, but heavy bleeding, dizziness, or black tarry stool is not typical and needs urgent evaluation. You should also get checked if bleeding continues even after pain improves, because not all rectal bleeding is from a fissure. If you are feeling unusually tired, labs to check for anemia can be helpful.
Do I need antibiotics for an anal fissure?
Most fissures are not infections, so antibiotics are not usually part of treatment. The focus is on softening stool, calming irritation, and relaxing the muscle spasm so the tear can close. Antibiotics may be considered only if there are signs of infection nearby, such as fever, worsening swelling, or a suspected abscess.