Hemorrhoids are swollen clusters of blood vessels, muscle, and connective tissue in and around the anal canal. They affect roughly half of all adults over age 50, making them one of the most common conditions people search for but rarely talk about. The good news: understanding what causes them gives you a clear path to preventing them or keeping mild cases from getting worse.
Hemorrhoids Are Normal Anatomy Gone Wrong
Here’s something most people don’t realize: hemorrhoidal tissue is a normal part of your body. Everyone has it. These vascular cushions are present before birth and remain throughout life, sitting inside the anal canal where they help with continence and cushion the passage of stool. There are typically three main cushions positioned around the inside of the canal.
Problems start when these cushions swell, stretch, or slip out of position. The connective tissue that anchors them weakens, blood pools in the vessels, and what was once a quiet part of your anatomy becomes inflamed, itchy, or painful. That’s the shift from normal hemorrhoidal tissue to hemorrhoidal disease, which is what people mean when they say “I have hemorrhoids.”
Internal vs. External Hemorrhoids
The two types form on opposite sides of an important boundary inside the anal canal called the dentate line. This distinction matters because it determines what you feel and what symptoms you’ll notice.
Internal hemorrhoids develop above the dentate line, where the tissue doesn’t have pain-sensing nerves. That’s why they typically don’t hurt. Their hallmark symptom is painless, bright red bleeding during a bowel movement, often noticed on toilet paper or in the bowl. As they progress, they can bulge out of the anal opening. Doctors grade internal hemorrhoids on a four-point scale: Grade 1 hemorrhoids bleed but don’t protrude. Grade 2 protrude during straining but slide back in on their own. Grade 3 protrude and need to be manually pushed back. Grade 4 stay prolapsed and can’t be pushed back in.
External hemorrhoids form beneath the dentate line, covered by skin that has plenty of nerve endings. These are the ones that hurt, itch, and swell. You can often feel them as a lump near the opening. When a blood clot forms inside an external hemorrhoid (called a thrombosed hemorrhoid), it becomes a firm, bluish lump that can cause sudden, intense pain.
What Causes Hemorrhoids
The underlying mechanism is increased pressure in the lower rectum and anal canal. That pressure engorges the blood vessels, stretches the supporting tissue, and eventually causes the cushions to swell or slide downward. Several specific factors create that pressure.
Straining during bowel movements is the most common trigger. When you bear down to pass a hard stool, you dramatically increase the pressure on the veins in your anal canal. Chronic constipation makes this worse because you’re straining repeatedly over weeks or months. Ironically, chronic diarrhea does the same thing through frequent irritation and pressure.
Sitting on the toilet too long is an underappreciated cause. The seated position on a toilet allows the anal cushions to engorge with blood, and prolonged sitting (scrolling your phone, reading) keeps that pressure sustained. Even 10 to 15 extra minutes per session adds up over time.
Low-fiber diets set the stage for constipation. Without enough fiber, stools become hard and difficult to pass, which leads right back to straining. The recommended daily fiber intake is about 14 grams per 1,000 calories you eat, which works out to roughly 28 grams a day on a standard 2,000-calorie diet. Most people fall well short of that number.
Heavy lifting on a regular basis raises intra-abdominal pressure in a way similar to straining on the toilet. If you hold your breath and bear down while lifting (the Valsalva maneuver), the effect is even more pronounced.
Obesity creates chronic pressure in the pelvic and rectal area simply from the extra weight the body carries.
Why Pregnancy Is a Major Risk Factor
Pregnancy creates a perfect storm for hemorrhoid development, which is why so many pregnant people deal with them, especially in the third trimester. The growing uterus presses directly on the veins in the pelvic region, compressing blood flow and causing those vessels to swell. At the same time, total blood volume increases significantly during pregnancy to support the fetus, which puts additional pressure on veins throughout the body, including the rectal area.
Hormones play a role too. Rising progesterone levels relax the walls of blood vessels, making the veins in the rectal area more prone to stretching and swelling. Progesterone also slows digestion, which can lead to harder stools and more straining. Add in the pressure from frequent urination and the intense pushing during labor, and it’s clear why hemorrhoids are so common during and after pregnancy.
How Aging Weakens the Supporting Tissue
Age is one of the biggest risk factors, and it has nothing to do with behavior. The connective tissue that anchors hemorrhoidal cushions in place naturally deteriorates over time. Research shows this tissue loses collagen content and develops altered collagen ratios as you get older, making it weaker and less able to hold the cushions in position. The result is that the cushions gradually slide downward, the blood vessels dilate, and hemorrhoidal disease becomes more likely. This is a big reason why prevalence jumps so sharply after age 50.
What Hemorrhoid Symptoms Feel Like
Symptoms vary depending on the type and severity, but the most common ones include:
- Painless bleeding during bowel movements, usually bright red blood on toilet paper or dripping into the bowl (most common with internal hemorrhoids)
- Itching or irritation around the anal area
- Swelling or a lump near the anus that you can feel with your fingers
- Pain or discomfort, particularly with external hemorrhoids or thrombosed hemorrhoids
- A feeling of fullness or incomplete bowel movements when internal hemorrhoids prolapse
Bleeding, thrombosis, and prolapse can occur independently or together, and they don’t always correlate with the size of the hemorrhoid. A small thrombosed external hemorrhoid can be extremely painful, while a larger internal hemorrhoid might cause no discomfort at all. If you notice dark red or black blood, or bleeding that doesn’t resolve, that warrants medical evaluation because those patterns can signal other conditions.
How Diet and Habits Help Prevent Flare-Ups
Since most hemorrhoids stem from pressure and straining, the most effective prevention targets those root causes. Increasing your fiber intake to the recommended 28 grams per day softens stools and makes them easier to pass. Good sources include beans, lentils, whole grains, fruits, and vegetables. Fiber supplements work too, but drinking plenty of water alongside fiber is essential. Without adequate fluids, extra fiber can actually make constipation worse. Fruit juices and clear soups count toward your fluid intake.
Beyond diet, a few habits make a real difference. Limit your time on the toilet to the minutes you actually need. Avoid straining or holding your breath during bowel movements. Go when you feel the urge rather than delaying, which allows stool to harden in the rectum. If you lift weights or do heavy physical work, exhale during exertion rather than holding your breath. Staying physically active in general helps keep your digestive system moving and reduces the likelihood of constipation.
When Hemorrhoids Need Medical Treatment
Most mild hemorrhoids respond to dietary changes, increased water intake, and over-the-counter topical treatments that reduce swelling and itching. Warm baths (sitting in a few inches of warm water for 10 to 15 minutes) can also ease discomfort during flare-ups.
For internal hemorrhoids that bleed persistently or prolapse, doctors can perform office-based procedures that cut off blood flow to the swollen tissue. These are generally quick, don’t require anesthesia, and involve minimal recovery time. Surgical removal is typically reserved for severe cases, particularly Grade 3 or 4 internal hemorrhoids that haven’t responded to other treatments.
Thrombosed external hemorrhoids present a specific scenario. If caught within the first 48 to 72 hours of symptom onset, surgical excision of the clot can provide rapid relief. After that window, the pain usually begins to resolve on its own over one to two weeks, and the clot is gradually reabsorbed by the body. Current clinical guidelines note that early excision can be beneficial for select patients, though the decision depends on the severity of pain and timing.