Hepatitis means inflammation of the liver. It is a descriptive medical term rather than the name of one disease, and it can result from infectious agents, alcohol, medications, toxins, autoimmune mechanisms, metabolic disorders and other causes. Viral hepatitis is particularly important globally and includes Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D and Hepatitis E. The different viral forms have distinct transmission routes, natural histories, preventive measures and treatments. Hepatitis can be acute, meaning relatively recent and potentially self-limited, or chronic, meaning persistent inflammation or infection that can cause progressive fibrosis and cirrhosis. WHO defines hepatitis as liver inflammation that can lead in some circumstances to severe liver damage and cancer.
The liver responds to injury through cellular and immune mechanisms that can produce inflammation and hepatocyte damage. Acute hepatitis may cause temporary disruption of liver function, while persistent injury can activate repair processes that result in fibrosis. Progressive fibrosis can eventually produce cirrhosis, in which normal hepatic architecture is extensively remodelled. Some chronic forms also increase the risk of hepatocellular carcinoma. The clinical severity of hepatitis varies considerably: an individual may have no symptoms, mild nonspecific illness, marked jaundice or, rarely, acute liver failure. Thus the word hepatitis alone does not establish either cause or prognosis. Determining the underlying mechanism is essential for diagnosis and management.
Symptoms of Hepatitis can include fatigue, reduced appetite, nausea, vomiting, abdominal discomfort, dark urine and jaundice, although many infections remain asymptomatic. Jaundice occurs when bilirubin accumulates in tissues and becomes visible in the skin and sclerae, but it is not present in every case. Acute hepatitis can also cause fever and other systemic symptoms. Chronic hepatitis may remain clinically silent for years or decades while fibrosis progresses. Consequently, absence of symptoms does not reliably exclude clinically important liver disease. Blood tests commonly assess aminotransferases and other markers of hepatic injury and function, while disease-specific serological or molecular tests determine the cause.
Viral Hepatitis A and Hepatitis E are typically transmitted through contaminated food or water, whereas Hepatitis B, Hepatitis C and Hepatitis D are predominantly associated with exposure to infected body fluids, particularly blood. Hepatitis B can additionally be transmitted sexually and from mother to child around birth. Hepatitis C is primarily bloodborne, while Hepatitis D requires the presence of Hepatitis B for infection. These distinctions are clinically important because prevention strategies differ. Vaccination is available against Hepatitis A and Hepatitis B, while there is currently no effective vaccine against Hepatitis C. WHO identifies Hepatitis B and C as the major chronic viral forms responsible for most viral-hepatitis-related deaths.
Diagnosis of Hepatitis usually begins with identifying evidence of liver injury and then determining its cause. Liver blood tests can show hepatocellular injury or impaired hepatic function, but abnormal results are not specific to viral hepatitis. Serological testing can identify antibodies or viral antigens, while nucleic-acid testing can detect viral genetic material and help determine whether active infection is present. Imaging may evaluate liver structure and complications, and fibrosis assessment can estimate chronic damage. In selected circumstances, liver biopsy provides microscopic information. The distinction between acute and chronic disease is particularly important because some infections resolve spontaneously whereas others can persist and require long-term monitoring or antiviral treatment.
Treatment depends entirely on the cause. Hepatitis A generally requires supportive management because most infections resolve without chronic infection, while Hepatitis B may require long-term antiviral therapy in people meeting treatment criteria. Hepatitis C can now be cured in more than 95 percent of treated people with appropriate direct-acting antiviral medicines, although access to testing and treatment remains incomplete worldwide. Autoimmune hepatitis requires immune-directed treatment, while alcohol-related hepatitis requires removal of the alcohol exposure and specialist management when severe. Drug-induced hepatitis requires identification and, where medically appropriate, withdrawal of the causative agent. These differences demonstrate why “treating hepatitis” is not a single therapeutic process.
A major distinction is between Hepatitis and fatty liver. Fatty liver describes excess lipid accumulation within hepatocytes, whereas hepatitis specifically denotes inflammation. The two can coexist, as inflammatory steatohepatitis can occur in metabolic or alcohol-associated liver disease. Hepatitis should also be distinguished from cirrhosis, which describes advanced architectural scarring rather than simply inflammation. Similarly, abnormal liver enzymes are laboratory findings rather than diagnoses. Another misconception is that all viral hepatitis behaves similarly. In reality, Hepatitis A usually does not become chronic, whereas Hepatitis B and C can produce chronic infection and long-term complications, making their natural histories fundamentally different.
The historical and public-health significance of Hepatitis is substantial because many forms are preventable, diagnosable and treatable yet remain underdiagnosed. Vaccination, blood screening, infection-control procedures, safe injection practices and harm-reduction measures have reduced transmission of several viral forms. WHO's current global strategy places particular emphasis on eliminating Hepatitis B and C as public-health threats through expanded prevention, testing and treatment. Hepatitis therefore represents both a clinical concept and a major public-health category. Understanding the precise cause, transmission route, acute or chronic status, degree of fibrosis and presence of complications is essential for interpreting the term correctly and for distinguishing one form from another.
