The symptoms are non-specific and vary widely, but it may present with the classical triad of: It is usually seen in younger adults, with the median age at diagnosis between 35 and 40 years, and it has a similar incidence in males and females.

The acute syndrome presents with rapidly progressive and severe upper abdominal pain, yellow discoloration of the skin and whites of the eyes, liver enlargement, spleen enlargement, fluid accumulation within the peritoneal cavity, elevated liver enzymes, and eventually encephalopathy.

Secondary Budd–Chiari syndrome, which is very rare compared to the primary variant, is due to compression of the hepatic vein by an outside structure (such as a tumor or polycystic kidney disease).

[15] Budd–Chiari syndrome is also seen in tuberculosis, congenital venous webs and occasionally in inferior vena caval stenosis.

An important non-genetic risk factor is the use of estrogen-containing forms of hormonal contraception, which is implicated in 22% of cases of Budd–Chiari syndrome.

[16] People who have paroxysmal nocturnal hemoglobinuria (PNH) appear to be especially at risk for Budd–Chiari syndrome, more than other forms of thrombophilia: up to 39% develop venous thromboses,[17] and 12% may acquire Budd–Chiari.

This leads to increased portal vein and hepatic sinusoid pressures as the blood flow stagnates.

Obstruction also causes centrilobular necrosis and peripheral lobule fatty change due to ischemia.

Kidney failure may occur, perhaps due to the body sensing an "underfill" state and subsequent activation of the renin-angiotensin pathways and excess sodium retention.

[2] With regards to secondary causes of hypercoagulability, 40–50% of cases of Budd–Chiari syndrome are due to myeloproliferative disorders, and these conditions each have their own specific treatments.

[2] A beta-blocker is indicated for prophylaxis against esophageal variceal bleeding and as needed diuretics can be used in cases of fluid overload in people with ascites.

TIPS accomplishes the same goal as a surgical shunt but has a lower procedure-related mortality, a factor that has led to a growth in its popularity.

[2] Pregnancy is not contraindicated in those with Budd Chiari syndrome and if it occurs, anticoagulants should be continued with low molecular weight heparin as the preferred agent, as warfarin is teratogenic (associated with birth defects).