Why Understanding the Cause Matters
No one likes to think about hemorrhoids, but if you’ve had them, you probably never want them again. The first step in preventing future flare-ups is understanding why they happen in the first place.
Hemorrhoids develop when pressure builds in the veins around your rectum, causing them to swell. Some causes—like diet and bathroom habits—are within your control, while others—such as aging or pregnancy—are unavoidable.
This article focuses on the physiological causes of hemorrhoids, explaining exactly what happens inside your body to trigger them. If you're looking for a breakdown of lifestyle and external factors that contribute to hemorrhoids, check out our article on the root causes of hemorrhoids [insert link].
How Hemorrhoids Form: The Chain Reaction
Hemorrhoids don’t appear overnight—they develop through a series of physiological events. Whether caused by constipation, prolonged sitting, or pregnancy, excessive pressure on the veins in the rectal area forces them to stretch and swell, leading to inflammation and discomfort.
Think of it like a traffic jam in your veins—when things aren’t moving properly, congestion builds up, leading to irritation.
Key Statistics:
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Nearly 75% of adults will experience hemorrhoids at some point. (Source: American Society of Colon and Rectal Surgeons)
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Constipation is a leading cause, affecting over 16% of adults globally. (Source: National Institute of Diabetes and Digestive and Kidney Diseases)
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Obesity increases the risk of hemorrhoids by up to 40% due to increased abdominal pressure. (Source: Mayo Clinic)
The Four Stages of Hemorrhoid Development
1. Constipation or Straining: The Initial Trigger
What Happens:
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When stool becomes hard and difficult to pass, people push harder to expel it.
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This increases abdominal pressure, putting strain on rectal veins.
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Straining slows down blood circulation, creating a pooling effect in the veins.
Why It Matters:
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Chronic constipation is responsible for 40% of symptomatic hemorrhoid cases. (Source: American Gastroenterological Association)
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Hard stools can also cause micro-tears in the anal canal, leading to irritation and bleeding.
2. Increased Pressure on the Veins: The Congestion Begins
What Happens:
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The blood vessels in the rectum and anus are delicate and not designed to handle prolonged pressure.
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Sitting for extended periods (especially on the toilet) restricts circulation, further weakening these veins.
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As the pressure increases, the veins stretch and become engorged with blood, making them more prone to inflammation.
Prolonged sitting accounts for 25% of hemorrhoid cases. (Source: American Gastroenterological Association)
Why It Matters:
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Once veins become swollen, they are easily irritated by bowel movements, wiping, and even everyday activities like walking or exercising.
3. Irritation & Inflammation: The Symptoms Begin
What Happens:
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Swollen veins rub against stool, skin, and clothing, leading to irritation.
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The body responds with inflammation, which triggers itching, discomfort, and swelling.
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In some cases, the veins may rupture, leading to rectal bleeding.
Why It Matters:
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Inflammation makes hemorrhoids more sensitive, which is why they become itchy and painful during flare-ups.
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Bleeding hemorrhoids aren’t necessarily dangerous, but persistent rectal bleeding should always be checked by a doctor to rule out other conditions.
4. Swelling & Discomfort: The Full-Blown Hemorrhoid
What Happens:
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The vein continues to swell, leading to increased sensitivity and pain.
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External hemorrhoids may form visible lumps, while internal hemorrhoids can create a sensation of fullness or an incomplete bowel movement.
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If the vein becomes thrombosed (clotted), it can cause extreme pain and may require medical intervention.
Up to 40% of people with symptomatic hemorrhoids experience significant swelling and discomfort. (Source: Mayo Clinic)
Why It Matters:
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At this stage, management and relief become the primary focus—whether through topical treatments, sitz baths, or lifestyle adjustments.
Final Thoughts: Why Understanding the Cause Helps Prevent Future Flare-Ups
Hemorrhoids follow a predictable physiological pattern, starting with pressure on the veins and ending with inflammation and discomfort.
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The good news? Knowing what’s happening inside your body helps you take action early, preventing minor irritation from turning into a full-blown hemorrhoid.
If you’re looking to dive deeper into the lifestyle and external factors that contribute to hemorrhoids, check out our article on the root causes of hemorrhoids [insert link].