Merck Manual

Please confirm that you are a health care professional

honeypot link

Causes of Hepatitis


Sonal Kumar

, MD, MPH, Weill Cornell Medical College

Last full review/revision Dec 2020| Content last modified Dec 2020
Click here for Patient Education
Topic Resources

Hepatitis is an inflammation of the liver characterized by diffuse or patchy necrosis.

Hepatitis may be acute or chronic (usually defined as lasting > 6 months). Most cases of acute viral hepatitis resolve spontaneously, but some progress to chronic hepatitis.

Common Causes of Hepatitis

Common causes of hepatitis include

At least 5 specific viruses appear to be responsible for hepatitis (see table Characteristics of Hepatitis Viruses). Other unidentified viruses probably also cause acute viral hepatitis.

Less Common Causes of Hepatitis

Less common causes of hepatitis include autoimmune disorders, genetic liver disorders, and other viral infections (eg, infectious mononucleosis, yellow fever, cytomegalovirus infection) and leptospirosis.

Parasitic infections (eg, schistosomiasis, malaria, amebiasis), pyogenic infections, and abscesses that affect the liver are not considered hepatitis. Liver involvement with tuberculosis (TB) and other granulomatous infiltrations is sometimes called granulomatous hepatitis, but the clinical, biochemical, and histologic features differ from those of the diffuse liver involvement in hepatitis caused by hepatitis viruses, alcohol, and drugs.

Various systemic infections and other illnesses may produce small focal areas of hepatic inflammation or necrosis. This nonspecific reactive hepatitis can cause minor liver function abnormalities but is usually asymptomatic.

Some types of infectious and noninfectious liver inflammation are summarized in table Selected Infections With Liver Involvement.


Selected Infections With Liver Involvement

Disease or Organism



In neonates: Hepatomegaly, jaundice, congenital defects

In adults: Mononucleosis-like illness with hepatitis; may occur posttransfusion

Epstein-Barr virus infections

Clinical hepatitis with jaundice in 5–10%; subclinical liver involvement in 90–95%

Acute hepatitis sometimes severe in young adults

Herpes simplex virus

Anicteric hepatitis, usually in immunocompromised patients (but can also occur in immunocompetent patients)

Fever in the majority; rash in 50%

Acute hepatitis, often severe

Jaundice, systemic toxicity, bleeding

Liver necrosis with little inflammatory reaction


Hepatic infection occasionally due to echovirus or coxsackievirus infections, varicella, herpes simplex, rubella, or rubeola


Granulomatous reaction of liver with progressive necrotizing abscesses

Pyogenic abscess*

Serious infection acquired via portal pyemia, cholangitis, or hematogenous or direct spread; due to various organisms, especially gram-negative and anaerobic

Illness and toxicity, yet only mild liver dysfunction

Hepatic involvement (common; usually subclinical) with granulomatous infiltration; jaundice (rare)

Disproportionately increased alkaline phosphatase


Minor focal hepatitis in numerous systemic infections (common; usually subclinical)


Granulomas in liver and spleen (usually subclinical) that heal with calcification


Granulomatous infiltration sometimes occurring in cryptococcosis, coccidioidomycosis, blastomycosis, or other infections


Important disease, often without obvious dysentery

Usually a large single abscess with liquefaction

Systemic illness, tender hepatomegaly, surprisingly mild liver dysfunction

A common cause of hepatosplenomegaly in endemic areas

Jaundice absent or mild unless active hemolysis is present

Transplacental infection

In neonates: Jaundice, central nervous system (CNS) and other systemic manifestations

Infiltration of reticuloendothelial system by parasite, hepatosplenomegaly


Biliary obstruction by adult worms, parenchymal granulomas caused by larvae

Biliary tract infestation, cholangitis, stones, cholangiocarcinoma

One or more hydatid cysts, which usually have a calcified rim and may be large but which often are asymptomatic and do not disrupt liver function

Can rupture into the peritoneum or biliary tract

Acute: Tender hepatomegaly, fever, eosinophilia

Chronic: Biliary fibrosis, cholangitis

Periportal granulomatous reaction to ova with progressive hepatosplenomegaly, pipestem fibrosis, portal hypertension, and varices

Hepatocellular function preserved; not true cirrhosis

Visceral larva migrans syndrome

Hepatomegaly with granulomas, eosinophilia


Acute fever, prostration, jaundice, bleeding, renal injury

Liver necrosis (often mild despite severe jaundice)

Congenital: Neonatal hepatosplenomegaly, fibrosis

Acquired: Variable hepatitis in secondary stage, gummas with irregular scarring in tertiary stage

Borrelia infection

Systemic symptoms, hepatomegaly, sometimes jaundice

*Differentiate from amebiasis with serologic tests for amebas and direct percutaneous abscess aspiration.

Drugs Mentioned In This Article

Drug Name Select Trade
Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Test your knowledge

Hepatitis E
There are 4 genotypes of the hepatitis E virus (HEV), and each of these genotypes can cause acute viral hepatitis. HEV was not originally thought to cause chronic hepatitis; however, reports have documented chronic hepatitis exclusively in immunocompromised patients. Which of the following genotypes is responsible for chronic hepatitis in these patients? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest