Hemorrhoids form when the cushion-like pads of blood vessels and connective tissue inside the anal canal become swollen, stretched, or displaced. These pads are normal anatomy that everyone has from birth. They help keep the anal canal closed at rest. Problems begin when pressure inside the abdomen rises and pushes blood into the veins around the rectum, or when the supporting tissue weakens over time. The result is an enlarged, sometimes painful or bleeding mass. The two main types are internal, which sit above the dentate line and usually do not hurt, and external, which sit below it and can be quite painful.
What Are Hemorrhoids Made Of?
Hemorrhoids are not abnormal growths or tumors. They are the same vascular cushions present in every healthy person. Each cushion is a network of small arteries and veins held together by elastic connective tissue and smooth muscle.
These cushions serve a purpose. They help the anal sphincter keep the canal sealed and contribute to fine control over bowel movements. In that sense, everyone has hemorrhoids. The word only describes a problem when these cushions enlarge, slide downward, or become inflamed.
The arteries feeding the cushions come from the superior rectal artery, a branch of the inferior mesenteric artery. Blood drains through veins that eventually empty into the portal system. Because this venous drainage has no valves, pressure from the abdomen can push backward into these vessels more easily than in veins elsewhere in the body. That anatomy is one reason the anal area is prone to swelling.
Two other structures matter. The anal sphincter is a ring of muscle that controls the opening. The dentate line is a visible landmark that separates the upper anal canal from the lower. Whether a hemorrhoid is called internal or external depends on which side of that line it sits.
How Do Hemorrhoids Form Causes And Risks?
The core mechanism is increased pressure combined with weakening support tissue. When pressure inside the abdomen rises repeatedly, blood backs up in the anal veins. At the same time, the connective tissue that holds the cushions in place stretches out.
Over time the cushions slide downward and enlarge. This is why hemorrhoids are more common with age. The tissue loses elasticity the way skin loses firmness over decades.
Several factors raise that pressure or weaken the tissue:
- Chronic constipation and straining during bowel movements
- Prolonged sitting on the toilet
- Pregnancy, especially in the third trimester
- Low-fiber diets that produce hard stool
- Obesity and excess body weight
- Heavy lifting that increases abdominal pressure
- Persistent diarrhea
- Long periods of standing or sitting
Pregnancy deserves a closer look. Pressure from the growing uterus, hormonal changes that relax veins, and the strain of delivery all combine to make hemorrhoids common during and after pregnancy. Many shrink after delivery, but some persist.
One point worth clarifying: sitting on cold concrete or a hot surface is often blamed for hemorrhoids. There is no strong evidence that surface temperature causes them. The real driver is internal pressure, not what you sit on.
What Is the Difference Between Internal and External Hemorrhoids?
The dentate line divides the two types, and that division explains why they feel so different.
Internal hemorrhoids sit above the dentate line. That area has few pain-sensing nerve endings. So internal hemorrhoids often cause no pain at all. The most common sign is bright red blood on the toilet paper or in the bowl. They may also protrude through the anus, a condition called prolapse.
Internal hemorrhoids are graded by how far they prolapse:
- Grade I: They bleed but do not prolapse.
- Grade II: They prolapse during a bowel movement but go back on their own.
- Grade III: They prolapse and must be pushed back manually.
- Grade IV: They stay prolapsed and cannot be pushed back.
External hemorrhoids sit below the dentate line, where nerve endings are dense. They can be painful, especially when a blood clot forms inside one. That clot is called a thrombosed hemorrhoid, and it produces a firm, tender lump.
Some people have both types at once. A skin tag near the anus is often the leftover of a past external hemorrhoid.
What Symptoms Do Hemorrhoids Cause?
Bleeding is the most common symptom. It is usually bright red because the blood comes from very close to the surface. You may notice it on toilet paper, on the stool, or as a few drops in the toilet.
Other symptoms include itching, irritation, a feeling of fullness or pressure, and a lump near the anus. Pain is more typical of external hemorrhoids, particularly when a clot forms.
Bleeding from the rectum is never something to assume is harmless. Conditions such as colorectal cancer and inflammatory bowel disease can cause similar bleeding. Anyone with rectal bleeding should have it evaluated by a clinician rather than assuming hemorrhoids are the cause. This is especially true after age 45 or with a family history of colorectal cancer.
Other warning signs that need prompt medical attention include a change in bowel habits lasting more than a few weeks, unexplained weight loss, and blood that is dark or mixed with stool.
Who Is Most at Risk?
Risk rises with age because the supporting tissue weakens. Roughly half of adults over 50 report symptoms at some point, though estimates vary by how the condition is defined.
Pregnancy is a major risk window. So are chronic constipation and a low-fiber diet. People whose jobs require heavy lifting or long hours of sitting face higher odds. Obesity adds risk because extra body weight raises pressure inside the abdomen.
Some risk factors can be changed and some cannot. Age and genetics fall into the fixed category. Diet, hydration, and bathroom habits are more within reach.
Can Hemorrhoids Be Prevented?
Prevention focuses on keeping stool soft and reducing strain. That is the same approach clinicians use to manage mild cases.
Adequate fiber and fluid intake are the foundation. The USDA recommends roughly 25 grams of fiber per day for adult women and 38 grams for adult men. Most Americans fall short of these targets. Adding fiber gradually, along with enough water, helps avoid the bloating that comes from a sudden jump.
Other practical steps include:
- Avoiding long stretches on the toilet
- Going when the urge comes rather than holding it
- Staying physically active
- Using proper lifting technique
- Not delaying a bowel movement out of habit
None of these steps guarantees prevention. They lower the odds by reducing the pressure that drives the problem.
When Should You See a Doctor?
See a clinician if bleeding is new, if pain is severe, or if a lump does not improve within a few days. A thrombosed external hemorrhoid is painful enough that prompt care can make a real difference.
Treatment ranges from conservative measures to office procedures and surgery. Many mild cases improve with fiber, fluids, and sitz baths. Persistent or high-grade cases may need procedures such as rubber band ligation, which cuts off blood flow so the tissue shrinks and falls off. More advanced cases may require surgical removal.
The choice depends on the type, grade, and symptoms. No single approach works for everyone, and what helps one person may not help another.
Frequently Asked Questions
Are hemorrhoids actually swollen veins?
Partly. They are enlarged vascular cushions made of arteries, veins, and supporting tissue, not just veins alone. That distinction matters because it explains why treatment targets both blood flow and tissue support.
Can hemorrhoids go away on their own?
Mild cases often improve within days to weeks with fiber, fluids, and less straining. Larger or prolapsed hemorrhoids are less likely to resolve without treatment.
Does sitting on a cold or hot surface cause hemorrhoids?
No strong evidence links surface temperature to hemorrhoids. The main drivers are internal pressure and weakened support tissue.
Is rectal bleeding always from hemorrhoids?
No. Bleeding can also come from colorectal cancer, inflammatory bowel disease, or other conditions. Any new rectal bleeding should be checked by a clinician.
