Viral hepatitis is inflammation of the liver caused by one of five main viruses, labeled A through E. Some forms clear on their own within weeks, while others can silently persist for decades, eventually leading to cirrhosis or liver cancer. Globally, an estimated 50 million people are living with hepatitis C alone, and hundreds of thousands die each year from complications of chronic hepatitis B and C combined.
How Hepatitis Viruses Damage the Liver
The viruses themselves don’t destroy liver cells directly. Instead, your immune system does most of the damage while trying to fight the infection. When immune cells detect virus-infected liver cells, they release inflammatory signals and toxic molecules called reactive oxygen species to kill those cells. This triggers a cycle of cell death, inflammation, and tissue repair.
In acute infections that resolve, the liver heals and returns to normal function. But when the infection becomes chronic, this cycle of destruction and repair never stops. Years of constant inflammation cause scar tissue to replace healthy liver tissue, a process called fibrosis. Left unchecked, fibrosis progresses to cirrhosis, where so much scarring accumulates that the liver can no longer function properly. The ongoing DNA damage from chronic inflammation also raises the risk of liver cancer.
The Five Types at a Glance
Each hepatitis virus spreads differently and poses different long-term risks.
Hepatitis A
Hepatitis A spreads through contaminated food, water, or close contact with an infected person (the fecal-oral route). It causes an acute illness that can last several weeks but never becomes chronic. Most people recover fully and are then immune for life. A highly effective vaccine exists and is part of routine childhood immunization in many countries.
Hepatitis B
Hepatitis B spreads through blood, sexual contact, and from mother to child during birth. The age at which a person is infected largely determines their outcome. Infants infected at birth develop chronic hepatitis B about 95% of the time, while adults who contract the virus clear it on their own in roughly 95% of cases, with fewer than 5% progressing to chronic infection.
Chronic hepatitis B has a notable ability to cause liver cancer even without first causing cirrhosis. In one large study, 69% of hepatitis B patients who developed liver cancer had never progressed through a cirrhotic stage, highlighting the virus’s direct cancer-promoting potential. This makes long-term monitoring especially important for people living with chronic hepatitis B.
Hepatitis C
Hepatitis C spreads primarily through direct blood-to-blood contact, such as sharing needles or, less commonly, through mucous membrane exposure. Unlike hepatitis B, most people infected with hepatitis C develop chronic infection. The virus tends to cause liver cancer through a slower path: progressive scarring that eventually becomes cirrhosis. In one study, 86% of hepatitis C patients who developed liver cancer had gone through a cirrhotic stage first.
The good news is that hepatitis C is now curable. Modern antiviral treatments, taken as pills for 8 to 12 weeks, achieve cure rates of about 97%. Before these treatments became available in 2014, hepatitis C therapy involved months of injections with harsh side effects and much lower success rates. No vaccine for hepatitis C currently exists, which makes screening and treatment the primary tools for controlling the virus.
Hepatitis D
Hepatitis D only infects people who already have hepatitis B, because it requires the hepatitis B virus to replicate. Co-infection with both viruses tends to cause more severe liver disease and faster progression to cirrhosis. Vaccination against hepatitis B effectively prevents hepatitis D as well.
Hepatitis E
Hepatitis E spreads through contaminated water, mainly in regions with poor sanitation. Like hepatitis A, it typically causes a self-limiting acute illness. The major exception is pregnancy: hepatitis E infection during the third trimester can cause fulminant liver failure, with maternal mortality reaching 15% to 25% in cases involving the most common genotype in endemic areas.
Symptoms and Why They’re Easy to Miss
Acute hepatitis symptoms, when they appear at all, can show up anywhere from 2 weeks to 6 months after exposure. They often include fatigue, nausea, abdominal pain, dark urine, and jaundice (yellowing of the skin and eyes). Many people, particularly those with hepatitis C, have no symptoms during the acute phase and don’t realize they’ve been infected.
Chronic hepatitis B and C can remain silent for decades. The liver has enormous functional reserve, so significant damage can accumulate before any symptoms surface. When symptoms of chronic infection finally appear, they’re typically the same as those of acute infection: fatigue, nausea, and jaundice. By that point, substantial liver scarring may already be present.
Screening Recommendations
Because chronic hepatitis so often produces no symptoms, screening is the main way infections get caught early. The CDC recommends that all adults aged 18 and older be tested for hepatitis C at least once in their lifetime. People with ongoing risk factors, such as current injection drug use, should be tested periodically. Anyone who requests a test should receive one, regardless of whether they disclose specific risk factors.
Hepatitis B screening is similarly recommended for pregnant women, people born in regions with high prevalence, and anyone with risk factors for blood-borne infection. A simple blood test can reveal whether you’ve never been exposed, are currently infected, have recovered from a past infection, or are immune through vaccination.
Prevention Through Vaccination
Effective vaccines exist for hepatitis A and hepatitis B, but not for hepatitis C or E (though a hepatitis E vaccine is licensed in China). The hepatitis B vaccine is given in three doses over six months. In healthy infants and children, the full course produces protective immunity in over 95% of recipients. Adults under 40 respond nearly as well, with protection rates above 90%, though effectiveness gradually declines with age, dropping to 65% to 75% by age 60.
For hepatitis B, vaccination doesn’t just prevent one disease. It also eliminates the risk of hepatitis D, which cannot exist without hepatitis B. Universal infant vaccination programs, now standard in most countries, have dramatically reduced new hepatitis B infections over the past three decades.
Long-Term Risks of Chronic Infection
The two chronic forms, hepatitis B and C, together account for most viral hepatitis deaths worldwide. The primary long-term risks are cirrhosis and hepatocellular carcinoma, the most common form of liver cancer. These complications typically develop over 20 to 30 years of chronic infection, though the timeline varies widely depending on factors like alcohol use, co-infections, and metabolic health.
The two viruses take somewhat different paths to cancer. Hepatitis C usually causes cancer through progressive liver scarring, meaning cirrhosis develops first. Hepatitis B, by contrast, can trigger cancer more directly by integrating its DNA into liver cells and causing genetic instability, which is why liver cancer screening matters even for hepatitis B patients without cirrhosis. In both cases, treating the underlying infection significantly reduces but does not eliminate the long-term cancer risk, making continued monitoring important even after successful treatment.