What Are Hemorrhoids? Complete Guide

Hemorrhoids are swollen, engorged cushions of tissue in the anal canal — not a foreign growth, but normal anatomical structures that everyone has, which become a “condition” specifically when they swell, bleed, or prolapse enough to cause symptoms.

Key takeaways

Everyone has hemorrhoidal tissue; “having hemorrhoids” refers to this normal tissue becoming swollen or displaced, not something new appearing.
They’re classified as internal (above the dentate line) or external (below it), and internal ones are further graded I–IV by degree of prolapse.
They’re extremely common and, in the large majority of cases, not dangerous — though a small share of anorectal symptoms have other, more serious causes worth ruling out (see this site’s differential diagnosis section).

The basic anatomy

The anal canal contains cushions of blood vessels, connective tissue, and smooth muscle that help with continence — sealing the anus between bowel movements and cushioning the area during passage of stool. These cushions sit both above the dentate line (internal) and below it (external), and are present in everyone from birth, serving a genuinely useful function.

What “having hemorrhoids” actually means

The condition happens when this normal tissue becomes engorged with blood, displaced downward (prolapse), or both — generally from increased pressure over time (straining, prolonged sitting, pregnancy) combined with some weakening of the connective tissue that normally holds the cushions in place. See Why do hemorrhoids happen? for the full mechanism.

Internal vs. external

Internal hemorrhoids develop above the dentate line, in an area with limited pain sensation — often causing painless bleeding without much discomfort, at least in earlier stages.
External hemorrhoids develop below the dentate line, in nerve-rich tissue — can cause significant pain, particularly if a blood clot forms within them (a thrombosed external hemorrhoid).

See Internal vs. external hemorrhoids for a fuller comparison.

How they’re graded

Internal hemorrhoids are classified by degree of prolapse, from grade I (no prolapse) to grade IV (permanently prolapsed) — see Hemorrhoid grades I–IV explained for the full breakdown with what each grade typically looks and feels like.

How common they are

Hemorrhoids are extremely common — estimates of symptomatic prevalence in the US general population are commonly cited around 4.4%, with roughly half of adults experiencing symptoms by age 50 in some estimates. See The epidemiology of hemorrhoids: what the real numbers are for a more careful look at the range of figures actually reported in research.

Are they dangerous?

In the large majority of cases, no — hemorrhoids themselves are a benign, common condition, not a serious disease. The more important point, covered throughout this site, is that hemorrhoid-like symptoms (rectal bleeding, in particular) have other possible causes, some of which do need prompt attention — this is why this site exists as a differential-diagnosis-first resource rather than a hemorrhoid-only one. See Are hemorrhoids dangerous? for the specific, direct answer.

What tends to happen to them over time

Mild hemorrhoids often improve or resolve on their own with basic self-care; some recur, particularly if underlying contributing factors (constipation, prolonged sitting) aren’t addressed. See Do hemorrhoids go away on their own? and Do hemorrhoids come back? for the fuller picture.

Where to go from here

If you’re not sure your symptoms are actually hemorrhoids, the most useful next stop is Is it hemorrhoids or something else? — the hub for this site’s entire differential diagnosis approach. If you’re confident this is a hemorrhoid and want to understand self-care, see Home care for hemorrhoids.

Want the difference between internal and external explained in depth? See Internal vs. external hemorrhoids.

This page is for general education.