Hepatitis causes

Last updated Feb. 21, 2025, by Lindsey Shapiro, PhD
Fact-checked by Marta Figueiredo, PhD

Hepatitis, a general term referring to liver inflammation, can have several possible causes, with the most common being an infection with a virus that targets the liver. Nonviral causes of hepatitis include an autoimmune disease and exposure to toxic substances, such as alcohol, drugs, or industrial chemicals. Unlike viral hepatitis, these forms of the liver disease are not contagious and don’t spread from person to person.

Hepatitis can eventually lead to significant liver damage and a loss of liver function if not properly diagnosed and treated. Managing hepatitis will depend on the underlying driver of liver inflammation, so it’s important to understand what causes hepatitis in each case.

The best way to avoid the potentially serious symptoms and complications of hepatitis is to prevent the disease from developing in the first place. While there are a range of different hepatitis risk factors that might make a person more likely to develop the liver disease, there are things a person can do to minimize that risk.

Viral hepatitis

The most common hepatitis causes worldwide are viral infections. Each of the five main forms of viral hepatitis — A, B, C, D, and E — is caused by a hepatitis virus of the same name. Once in the body, these viruses infect liver cells, triggering inflammation and damage that can eventually disturb normal liver function.

Each of the hepatitis viruses spreads in a somewhat different way, but none is airborne, meaning they are not spread through things like coughing and sneezing. These viruses are also not generally transmitted through casual contact such as sharing eating utensils, hugging or kissing, or shaking hands.

Anyone can get viral hepatitis, but for each type, there are certain risk factors that could make an infection more likely.

Hepatitis A

Hepatitis A is caused by the hepatitis A virus (HAV). Most often, HAV is contracted via the fecal-oral route, where the feces of a person with hepatitis A contaminate something that’s then ingested by another person. It can also occur through close physical contact, but not casual contact, with an infected person. Hepatitis A is most common in low- or middle-income countries with poor sanitation practices and a lack of safe drinking water.

Ways a person might contract hepatitis A include:

eating food prepared by an infected person who did not properly wash their hands after using the bathroom
drinking sewage-contaminated or improperly cleaned water or eating foods that have been rinsed with contaminated water
having oral-anal sex with an infected person
sharing needles with an infected person
caregiving for an infected person.

Hepatitis A risk factors include:

poor sanitation and lack of access to clean water
travel to countries where the infection is most prevalent (including certain parts of Africa and Asia), without being vaccinated
living with or having sex with a person who has hepatitis A
caring for a person with hepatitis A, especially where there’s a risk of exposure to fecal matter (e.g. daycare or healthcare setting)
sex between men
being homeless
illegal drug use.

Hepatitis B

The hepatitis B virus (HBV), which causes hepatitis B, is generally spread when bodily fluids such as blood, semen, or vaginal fluids from an infected person enter someone else’s body.

In the U.S., hepatitis B is most commonly contracted from injecting drugs or having multiple sex partners. HBV can also be spread from mother to infant during childbirth — with both a vaginal or Cesarean delivery — but not through breastfeeding.

Other ways a person might contract hepatitis B include:

having sex with an infected person
sharing equipment contaminated with the blood of someone with hepatitis B, including needles used for recreational drugs, body piercing and tattoos, or medical equipment like a blood sugar monitor
being accidentally stuck with a needle that was used on someone with hepatitis B, which may happen in healthcare settings
sharing daily objects like a toothbrush or razor with an infected person, if there is broken skin or open sores.

HBV can survive for about a week outside the body, so any contaminated object, if not properly sterilized, can still carry the virus and cause an infection during that period.

Hepatitis B risk factors include:

being born to a mother with hepatitis B
injecting drugs or sharing needles and other drug equipment
living with or having unprotected sex with an infected person
being a man who has sex with men
having a job with a risk of blood exposure, including healthcare or public safety workers
living in or traveling to areas where hepatitis B is common (such as certain African and Southeast Asian countries), without being vaccinated
having certain other medical conditions, including hepatitis C or human immunodeficiency virus (HIV), being on dialysis for kidney problems, or having existing liver damage.

Hepatitis C

Hepatitis C is caused by the hepatitis C virus (HCV), which is mainly spread through exposure to blood from an infected person. Hepatitis C can be contracted in many of the same ways as hepatitis B. However, HCV is much less likely than HBV to be transmitted through sex or from a mother to her infant during childbirth.

Before 1992, blood transfusions or organ transplants received from an infected donor were common hepatitis C causes. With better screening practices, this type of transmission has become very rare in recent years. In the U.S., needle sharing for injecting drugs is the most common way people get hepatitis C nowadays. Improper sterilization of medical equipment in healthcare settings can also cause it.

There are a variety of hepatitis C risk factors, many of which overlap with those for hepatitis B. People who may be at an increased risk of hepatitis C include:

injectable drug users
those with certain medical conditions, including people who’ve received dialysis, those with persistently abnormal liver enzyme levels, and people with HIV
people who received human blood products, blood transfusions, or organ transplants before 1992
those who may be exposed to HCV-contaminated blood at their job, such as healthcare or public safety workers
people who have worked or lived in a prison
men who have sex with men.

People who live in parts of the world where hepatitis C is more prevalent, including Africa, most parts of Asia, and eastern Europe, may also be at an increased risk of developing it.

Hepatitis D

Hepatitis D is caused by the hepatitis D virus (HDV) and can only be contracted by people who are already infected with HBV. That’s because, distinct from other hepatitis viruses, HDV can’t replicate and infect human cells on its own — it needs the help of HBV to do so.

HDV is spread in much the same ways as HBV — through contact with the bodily fluids of an infected person — and its risk factors are also generally similar.

People living in regions where hepatitis D is more frequent may also be at an increased risk of contracting it. That includes certain parts of Europe, Africa, and Asia, the Middle East, and the Amazon River Basin in South America.

Hepatitis E

Like the hepatitis A virus, the hepatitis E virus (HEV) is primarily spread through the fecal-oral route. People at the highest risk of contracting hepatitis E are those that live in or have recently traveled to countries where the disease is most prevalent. These mostly include low- and middle-income countries where sanitation is poor and access to clean drinking water is limited.

Less often, hepatitis E can be contracted by ingestion of undercooked meat from an animal that was infected with the virus, particularly pork or wild game. This is the most common mode of transmission in developed countries such as the U.S.

Toxic hepatitis

Toxic hepatitis is an umbrella term for when liver inflammation is caused by exposure to a toxic substance. One of the liver’s many roles is to filter medications and other chemicals out of the bloodstream and break them down for removal. Toxic hepatitis can arise when a substance breaks down into damaging chemical byproducts, or if the liver is overwhelmed by having to break down too much of a molecule.

Possible causes of toxic hepatitis include:

heavy alcohol consumption, which causes what’s known as alcohol-induced hepatitis
over-the-counter and prescription medications, as well as herbs and supplements, which cause drug-induced hepatitis
industrial chemicals.

Alcohol-induced hepatitis

Alcohol-induced hepatitis, formerly known as alcoholic hepatitis, develops when a person consumes excessive amounts of alcohol. This gives the liver too much to process, resulting in the accumulation of toxic molecules and inflammation that can damage the organ.

People most at risk for alcohol-induced hepatitis are those who have heavily used alcohol for a long period of time. But there is no specific amount of alcohol that will cause liver inflammation, and some people may be more sensitive to its effects than others.

Excessive alcohol use and other lifestyle factors are also associated with the buildup of fat in the liver — called fatty liver disease or hepatic steatosis — which can progress to cause hepatitis. This is a distinct condition from alcohol-induced hepatitis.

Drug-induced hepatitis

Drug-induced hepatitis can develop as a side effect to certain medications, herbal remedies, and dietary supplements, which can cause liver toxicity as the organ tries to break them down. This can occur after many months of using these substances, but drug-induced hepatitis can also be sudden in some cases.

Over-the-counter and prescribed medications, as well as herbs and supplements, that can cause hepatitis, include:

nonsteroidal anti-inflammatory medications to relieve pain and fever such as aspirin and ibuprofen (the active agent in Advil and Motrin IB)
medicines containing the pain and fever reliever acetaminophen (sold as Tylenol, among others)
certain antibiotics and antiviral medications
birth control pills
anabolic steroids, or medications made to mimic male sex hormones
treatments for epilepsy
cholesterol-lowering medications (statins)
certain cancer treatments
some herbal and dietary supplements, including green tea extracts, aloe vera, black cohosh, and cascara.

Not every person will develop drug-induced hepatitis from these substances, and it is not easy to predict who will. Some risk factors for drug-induced hepatitis include:

drinking alcohol and taking medicines at the same time, or taking multiple medicines that can interact with each other
taking medicines at high doses or for long periods of time
older age
being female
having another liver disease
being overweight or having diabetes
being pregnant
smoking
having genetic mutations that influence how substances are broken down in the body.

Industrial chemical-induced hepatitis

Exposure to certain industrial chemicals, most often at the workplace, can also be toxic to the liver and cause hepatitis. Chemicals that can cause hepatitis include:

carbon tetrachloride, a cleaning solvent
vinyl chloride, a molecule used to make plastics
paraquat, a herbicide
polychlorinated biphenyls, a group of man-made chemicals previously used in lubricants and in electrical and hydraulic equipment.

People who work in industries where these chemicals are used are at the highest risk. Hazardous response workers, first responders, or people who work in confined spaces are also at an increased risk. Having other hepatitis risk factors may also increase the likelihood that a person will develop hepatitis after being exposed to such chemicals.

Autoimmune hepatitis

Autoimmune hepatitis is a rare form of hepatitis caused by abnormal immune responses that involve the production of self-reactive antibodies against healthy liver cells, resulting in liver inflammation and damage.

While it remains largely unclear why some people develop autoimmune hepatitis, the disease is believed to arise through a combination of genetic and environmental factors. Autoimmune hepatitis has also been linked to hypergammaglobulinemia, a condition marked by elevated levels of antibodies in the blood.

Risk factors for autoimmune hepatitis include:

being female
certain genetic variants associated with immune function
having other autoimmune diseases such as thyroiditis, Graves’ disease, type 1 diabetes, inflammatory bowel disease, celiac disease, and rheumatoid arthritis
a history of past viral infections, including viral hepatitis, measles, herpes, or mononucleosis
use of certain medications, including the antibiotics nitrofurantoin and minocycline and the cholesterol-lowering atorvastatin.

Risk factors for hepatitis

There are many different factors that could influence a person’s risk of developing hepatitis, with risk factors varying by the disease’s underlying cause. In general, people may be at a higher risk of getting hepatitis if they:

practice unprotected sex or have multiple sex partners
share needles or use illegal injectable drugs
drink a lot of alcohol
work in settings where exposure to contaminated blood products is more likely, such as healthcare institutions
work where exposure to industrial chemicals is possible
have other autoimmune diseases or a family history of such conditions
use certain over-the-counter or prescription medications
travel to areas with poor sanitation.

Prevention strategies

Among the forms of viral hepatitis, highly effective vaccines are available to provide long-term protection against hepatitis A and hepatitis B. Getting vaccinated is the best way to prevent these forms of the liver disease.

Because HDV only infects people with hepatitis B, the vaccine against HBV will also protect against hepatitis D. A vaccine for hepatitis E has been developed, but it is not widely available.

For forms of hepatitis where no vaccine is available, or if a person cannot be vaccinated, the best prevention method is to avoid exposure to the virus. There are many steps a person can take to help protect themselves, including:

practicing safe sex, including using a condom
avoiding shared needles to take drugs
avoiding tattooing or piercing instruments, medical equipment, or anything else that is not sterile or could be contaminated
practicing good hygiene, including washing hands with soap and water after using the bathroom, caring for an infected person, and before preparing or eating food
avoid using personal items like toothbrushes or razors that belong to an infected person
taking certain precautions when traveling to areas with poor sanitation or where hepatitis is most prevalent, including making sure to be up to date on vaccines before departing and drinking bottled water once there.

Women who are pregnant should be tested for hepatitis B and C. Infants born to a mother with hepatitis B can receive the first dose of a hepatitis B vaccine as well as a medication called hepatitis B immune globulin in the hours after birth to lower their odds of developing the disease. Babies born to a mother with hepatitis C will have to be monitored for the infection, but there is no specific way to prevent it.

Because scientists don’t fully understand the causes of autoimmune hepatitis, there is no guaranteed way to prevent it. For toxic hepatitis, including forms caused by alcohol, drugs, or other chemicals, eliminating or limiting exposure to the offending substance is the best way to prevent hepatitis from developing. Using medications safely and exactly as prescribed can also help.

Liver Disease News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.