There are five main types of viral hepatitis, labeled A through E, each caused by a different virus with distinct transmission routes and health risks. Beyond these five, hepatitis can also be caused by alcohol, medications, toxins, and autoimmune conditions, bringing the total number of recognized forms well above five. Together, chronic hepatitis B and C alone account for 1.3 million deaths worldwide each year from liver disease and cancer.
Hepatitis A
Hepatitis A spreads through the fecal-oral route, meaning you catch it by ingesting something contaminated with the virus. That can happen through close contact with an infected person, contaminated food or water, or sexual contact. The incubation period averages about 28 days, with a range of 15 to 50 days.
The good news is that hepatitis A never becomes chronic. Most people recover fully with no lasting liver damage, though severe cases occur more often in older adults and people with existing liver disease. A safe, effective vaccine is available for anyone six months and older, and it remains the most reliable form of prevention.
Hepatitis B
Hepatitis B is a blood-borne virus that spreads through contact with infected blood, semen, and other body fluids. The most common routes are mother-to-child transmission during birth, sexual contact, and sharing needles. Less common pathways include sharing razors, toothbrushes, or contact with open sores. Symptoms can take a long time to appear, with an incubation period averaging 90 days (range of 60 to 150 days).
What makes hepatitis B particularly dangerous is how strongly the risk of chronic infection depends on age. Infants infected at birth develop chronic hepatitis B about 95% of the time. For children infected between ages one and five, that rate drops to 25% to 50%. Adults who are newly infected have less than a 5% chance of becoming chronically infected. Globally, roughly 254 million people currently live with chronic hepatitis B, and 1.2 million new infections occurred in 2022 alone.
A vaccine for hepatitis B has been available for decades and is routinely given to newborns. Several vaccine formulations exist, including combination vaccines that protect against both hepatitis A and B.
Hepatitis C
Hepatitis C spreads primarily through direct blood-to-blood contact, most commonly by sharing needles or other drug-injection equipment. Less common routes include transmission from mother to child during birth, sexual contact, unregulated tattooing, and needlestick injuries. The incubation period ranges widely, from 14 days to about six months.
Unlike hepatitis A, hepatitis C frequently becomes chronic. Over 50% of newly infected people develop a long-term infection, and among those with chronic hepatitis C, 15% to 25% will develop serious liver disease, including cirrhosis, liver failure, or liver cancer. The risk of cirrhosis climbs to 5% to 25% over a 10- to 20-year period, and people who reach that stage face a 1% to 4% annual risk of liver cancer.
The transformation in treatment over the past decade has been dramatic. Modern antiviral medications taken by mouth for just 8 to 12 weeks cure hepatitis C in more than 95% of cases. A person is considered cured when no virus is detectable in their blood 12 weeks after finishing treatment. There is no vaccine for hepatitis C.
Nearly 50 million people worldwide are living with chronic hepatitis C, and about 1 million new infections occurred in 2022.
Hepatitis D
Hepatitis D is unique among the five types because it cannot exist on its own. It’s classified as a “satellite virus,” meaning it can only infect someone who is already infected with hepatitis B. The hepatitis D virus hijacks the surface proteins of the hepatitis B virus to replicate and spread.
There are two ways a person can end up with hepatitis D. Coinfection happens when someone contracts both hepatitis B and D at the same time. Superinfection occurs when a person already living with chronic hepatitis B later picks up hepatitis D. Superinfection tends to be more serious, often accelerating liver damage. Because hepatitis D depends entirely on hepatitis B, the hepatitis B vaccine indirectly protects against hepatitis D as well.
Hepatitis E
Hepatitis E has four major genotypes that infect humans, and they behave quite differently depending on geography. Genotypes 1 and 2 are the most common forms in Africa and parts of Asia. They spread through contaminated drinking water and can cause massive outbreaks affecting thousands of people at once.
Genotypes 3 and 4 work differently. These primarily circulate in animals and occasionally jump to humans through consumption of raw or undercooked meat, particularly pork and game. Environmental contamination is also a likely source. Hepatitis E is typically a short-term illness, though it can be dangerous for pregnant women and people with compromised immune systems. No widely available vaccine exists in most countries.
Alcoholic Hepatitis
Not all hepatitis comes from a virus. Alcoholic hepatitis develops when years of heavy drinking (or repeated binge drinking) damage liver cells. When the liver processes alcohol, it produces toxic byproducts that injure liver tissue. The body’s immune response to that damage creates a cycle of inflammation that can compound the injury further.
People with alcoholic hepatitis are especially vulnerable to additional liver stress. Even standard doses of acetaminophen (Tylenol), which is normally safe for healthy adults, can worsen existing liver inflammation or trigger acute liver failure in someone with alcohol-related liver disease, particularly when taken repeatedly or alongside continued drinking.
Toxic and Drug-Induced Hepatitis
Certain medications, even common over-the-counter ones, can damage the liver enough to cause hepatitis. Acetaminophen is the single highest-risk widely used medication for liver injury, especially in high doses or when combined with alcohol. Common pain relievers like ibuprofen, naproxen, and aspirin carry a lower but still recognized risk. The FDA maintains a database tracking over 1,300 approved drugs for their potential to cause liver injury.
Industrial chemicals and solvents can also cause toxic hepatitis through workplace or environmental exposure. Herbal supplements are another underappreciated source of liver damage, partly because they are not regulated as strictly as prescription drugs and can contain compounds that are directly toxic to liver cells.
Autoimmune Hepatitis
In autoimmune hepatitis, the body’s immune system mistakenly attacks healthy liver cells, causing chronic inflammation. The trigger is not a virus, alcohol, or toxin. It is an immune system malfunction. Autoimmune hepatitis can develop at any age and tends to affect women more often than men. Without treatment, it can progress to cirrhosis, but it responds well to medications that suppress the overactive immune response.
How Hepatitis Is Detected
Doctors use blood tests to identify both the type and severity of hepatitis. Two liver enzymes, ALT and AST, serve as the front-line indicators. When liver cells are damaged, these enzymes leak into the bloodstream, and elevated levels signal that something is harming the liver.
To pinpoint which virus is involved, labs test for specific antibodies and viral genetic material. For hepatitis C, for example, an initial antibody test shows whether your body has ever been exposed to the virus, but a positive result alone doesn’t confirm a current infection. A follow-up test that looks for the virus’s genetic material in your blood confirms whether the infection is still active. Quantitative viral load tests measure how much virus is circulating, which helps track how well treatment is working.
Which Types Have Vaccines
Vaccines currently exist for hepatitis A and hepatitis B only. There are no approved vaccines for hepatitis C, D, or E in most parts of the world. However, because hepatitis D requires hepatitis B to survive, getting vaccinated against hepatitis B effectively prevents hepatitis D as well. A combination vaccine covering both hepatitis A and B is available for adults 18 and older.