Most episodes of diverticular bleeding stop on their own within 24 to 72 hours. Roughly 70 to 90 percent of cases resolve without any intervention, though some people experience bleeding that lasts longer or returns after initially stopping. If you’re hospitalized, the average stay runs about five to six days, which accounts for monitoring, testing, and making sure the bleeding has truly stopped.
What the Bleeding Looks Like
Diverticular bleeding typically shows up as painless, bright red or maroon-colored blood in the toilet or on toilet paper. Unlike other causes of rectal bleeding, there’s usually no cramping or abdominal pain accompanying it. The volume can range from a few streaks to a toilet bowl full of blood, which understandably causes alarm. A small amount that stops within a day or two is the most common scenario, but heavier bleeding can cause lightheadedness, weakness, or a rapid heartbeat, all signs that you’re losing enough blood to need medical attention.
Why It Stops on Its Own
Diverticula are small pouches that form along the wall of the colon, most often in the left side. Bleeding happens when a small blood vessel inside or near one of these pouches erodes and ruptures. In most cases, the body’s normal clotting process seals the vessel without help. One hospital-based study found that bleeding stopped spontaneously in about 69 percent of admitted patients, consistent with the broader 70 to 90 percent range reported across research.
The bleeding can be intermittent before it fully resolves. You might see blood, then nothing for several hours, then blood again. This stop-and-start pattern can stretch over one to three days and still fall within the range of a self-resolving episode.
What Happens in the Hospital
If you go to the emergency room with significant rectal bleeding, doctors will first stabilize you with fluids and check your blood counts to gauge how much blood you’ve lost. From there, the main diagnostic tool is a colonoscopy. U.S. and Japanese guidelines recommend performing a colonoscopy within 24 hours of arrival to locate the bleeding source, though European and British guidelines take a less urgent approach and don’t necessarily push for early colonoscopy as routine practice.
During the colonoscopy, if doctors find the specific diverticulum that’s bleeding, they can treat it on the spot using clips or bands to seal the vessel. When bleeding is too heavy for a colonoscopy to provide a clear view, an angiogram (imaging of the blood vessels) can both locate the bleed and allow treatment through a catheter. This approach is typically reserved for more severe cases, particularly when blood pressure drops below 90 systolic or the patient needs five or more units of transfused blood within 24 hours.
Surgery to remove part of the colon is a last resort, used only when both endoscopic treatment and catheter-based treatment fail to control the bleeding.
Medications That Increase Risk
Regular use of aspirin and anti-inflammatory painkillers like ibuprofen and naproxen significantly raises the risk of diverticular bleeding. In a large prospective study, men who took aspirin at least twice a week had a 70 percent higher risk of diverticular bleeding compared to nonusers. Those taking it four to six days per week had more than three times the risk. Non-aspirin anti-inflammatory drugs carried a similar increase, at 74 percent higher risk.
These medications interfere with the blood’s ability to clot and can irritate the lining of the colon, making an existing diverticulum more likely to bleed and potentially harder to stop. If you’ve had an episode of diverticular bleeding, your doctor will likely reassess whether you need to continue these medications or switch to alternatives.
Risk of Bleeding Again
Even after a first episode resolves completely, diverticular bleeding has a meaningful chance of coming back. The recurrence rate depends partly on how the initial bleed was treated. In one study comparing two endoscopic treatment methods, patients who had band ligation had an 11.5 percent chance of rebleeding within one year, while those treated with clips had a 37 percent chance. Without any endoscopic treatment (because the bleeding stopped before the source was found), recurrence rates generally fall somewhere in that range.
Recurrent episodes tend to follow the same pattern as the first: sudden, painless bleeding that usually stops on its own. But each recurrence raises the likelihood of needing more aggressive treatment. After two or more significant episodes, surgery to remove the affected section of colon becomes a more serious consideration.
Recovery After an Episode
Once the bleeding stops, recovery focuses on resting the digestive tract and gradually returning to normal eating. Most people start with clear liquids for a short period, then move to small amounts of easily digestible food, including about one to two ounces of protein per meal alongside other low-fiber options. Drinking plenty of water during this phase is important.
Over the following weeks, you’ll slowly reintroduce fiber into your diet. This transition typically happens over two to four weeks rather than all at once, since a sudden jump in fiber can irritate the colon. Once fully healed, a high-fiber diet is generally encouraged for long-term colon health and to reduce the risk of future diverticular problems. Your timeline for returning to normal activity depends on how much blood you lost and whether you needed any procedures, but most people who had a self-resolving episode feel back to normal within a week or two of leaving the hospital.