Aortic dissection happens when there is a tear in the inner lining of the aorta and blood forces its way into the wall of the vessel, and this almost always occurs in an aorta that has been weakened over time by other conditions.

What causes aortic dissection?

The core problem

  • Aortic dissection begins with a tear in the inner layer (intima) of the aorta, allowing blood to track between the layers of the wall and split them apart.
  • This tear almost never appears “out of nowhere”; it usually sits on top of chronic damage or weakness in the aortic wall from high blood pressure, genetic disorders, or atherosclerosis.

Major medical risk factors

  • Long‑standing high blood pressure (hypertension) : The single most important risk factor; constant high pressure gradually damages the aortic wall and makes it prone to tearing.
  • Atherosclerosis (hardening of the arteries) : Fatty plaque and calcium stiffen and weaken the aortic wall, increasing the chance of dissection, especially in older adults.
  • Age and sex : Dissections are more common in men over about 60–70 years old.
  • Pre‑existing aortic aneurysm : A dilated, bulging segment of the aorta has thinner, weaker walls that can dissect or rupture.

Genetic and structural causes

  • Connective tissue disorders : Conditions like Marfan syndrome and Ehlers‑Danlos syndrome make the aortic wall more fragile, so dissections can occur at a younger age and with less obvious triggers.
  • Congenital heart or aortic problems : Bicuspid aortic valve, coarctation (narrowing) of the aorta, and some other congenital defects raise stress on certain segments of the aorta and predispose them to dissection.
  • Family history : Having close relatives with aortic aneurysm or dissection suggests an inherited tendency toward weaker aortic tissue.

Triggers and lifestyle‑related factors

  • Sudden severe blood‑pressure spikes : Strenuous weight lifting, intense exertion, or sudden emotional stress can sharply increase pressure and “trigger” a tear in someone whose aorta is already vulnerable.
  • Stimulant drug use : Cocaine, amphetamines, and similar drugs acutely raise blood pressure and stress on the aorta, and are recognized triggers of dissection, particularly in younger patients.
  • Traumatic chest injury : High‑speed car crashes or major blunt trauma can physically tear the aorta or its inner lining.
  • Pregnancy‑related hypertension : High blood pressure during pregnancy can, in rare cases, contribute to dissection in women who are predisposed.

Why “random” cases still have causes

  • In many stories and forum discussions, aortic dissection is described as “sudden” or “out of the blue,” but in most cases, microscopic damage in the aorta has been developing silently for years.
  • Often, only after a dissection do clinicians uncover underlying issues such as previously undiagnosed high blood pressure, a mild aortic aneurysm, or a subtle genetic/connective‑tissue problem.

Important: Aortic dissection is a medical emergency. Any sudden, severe chest, back, or tearing pain, with or without collapse, needs immediate emergency evaluation. This information is educational and not a substitute for seeing a healthcare professional.

TL;DR: What causes aortic dissection?
Aortic dissection is usually caused by a combination of long‑term aortic wall weakening (high blood pressure, atherosclerosis, genetic/connective‑tissue disorders, aneurysm) plus a trigger such as a sudden blood‑pressure surge, heavy exertion, stimulant drug use, or trauma.

Information gathered from public forums or data available on the internet and portrayed here.