Background
Hepatitis A and Hepatitis B are two different viruses that attack the liver. While both cause liver inflammation and share similar names, they are distinct in how they spread, the symptoms they cause, and the long-term health issues they may lead to.
People have been dealing with hepatitis-like illnesses for thousands of years. Historical descriptions of jaundice (yellowing of the skin and eyes), a classic symptom of hepatitis, appear in writings from ancient Egypt, Greece, and Rome. What we now know as hepatitis A was often referred to as “epidemic jaundice” during the Middle Ages. However, .
Hepatitis B also has a long history. Writings from as far back as 400 BCE . In 1883, German shipyard workers developed jaundice after being vaccinated with smallpox material that included human lymph—. In the 1960s, researchers discovered the “,” now known as the hepatitis B surface antigen, and later fully identified the virus in 1970.
For a long time, the two infections were grouped under different labels: hepatitis A was “infectious hepatitis,” and hepatitis B was “serum hepatitis.” By the 1940s, they were recognized as separate diseases. Today, we have reliable tests that can accurately identify each one.
Signs, Symptoms, and Causative Agent
Signs & Symptoms
Hepatitis A symptoms . Many children under the age of 6 don’t show any symptoms at all. When symptoms do appear, they may include fatigue, nausea, stomach pain (especially near the liver), light-colored stools, loss of appetite, fever, dark urine, and jaundice. Most people recover within a few weeks or months, and the virus doesn't cause long-term liver damage.
Hepatitis B is harder to detect at first because . When symptoms do develop—often between 60 and 150 days after exposure—they may include fever, fatigue, muscle and joint pain, loss of appetite, nausea, vomiting, pale stools, dark urine, and jaundice. Most adults recover fully, but .
Causative Agent
Hepatitis A is caused by the (HAV). It infects the liver and is shed in large amounts through the stool, especially during the two weeks before symptoms appear. That’s when a person is most contagious.
Hepatitis B comes from the (HBV). Unlike HAV, HBV can stay in the body long term. One key part of the virus is the hepatitis B surface antigen (HBsAg), a protein that appears in the blood during infection. In people with chronic hepatitis B, the virus continues to multiply and may damage the liver over time.
Diagnostic Methods
To diagnose hepatitis A, . The IgM antibody shows up early in the illness and confirms a recent infection. IgG antibodies indicate past infection or immunity from vaccination.
For hepatitis B, . These include tests for the surface antigen (HBsAg), the antibody to the surface antigen (anti-HBs), and the core antibody (anti-HBc). These help determine if someone is currently infected, has had the infection before, or is immune. As of March 2023, .
Modes of Transmission
Hepatitis A , which means the virus leaves the body in stool and enters another person’s body when it’s accidentally swallowed. This can happen through close contact, consuming contaminated food or water, or traveling to regions where hepatitis A is more common. The highest risk of spreading the virus is in the two weeks before symptoms appear.
Hepatitis B . It can be passed from mother to baby during childbirth, through unprotected sex, by sharing personal items like razors or toothbrushes, through direct contact with open wounds, or by sharing needles or drug injection equipment. It is not spread through food or water.
In summary, hepatitis A is mostly spread by ingesting contaminated material, while hepatitis B spreads through exposure to infected fluids.
Treatment and Care
There is no antiviral medication for hepatitis A. Most people recover with supportive care—rest, hydration, healthy eating, and avoiding alcohol or medications that stress the liver. , but some people may feel sick on and off for up to six months.
Treatment for hepatitis B . Acute cases usually resolve on their own. Chronic hepatitis B may require antiviral medication to control the virus and reduce liver damage. These medications don’t cure the infection, and some people may need to take them for the rest of their lives.
Possible Known Complications of the Disease
Hepatitis A generally doesn’t lead to long-term liver problems. However, in rare cases—especially in older adults or people with liver disease—, which may require a transplant.
Chronic hepatitis B can lead to , including liver scarring (cirrhosis), liver failure, and liver cancer. Regular monitoring and treatment can help reduce these risks. People with chronic hepatitis B should also get regular screenings for liver cancer, which helps catch problems early.
Infants who get hepatitis B at birth : about 90% will develop chronic infection. Among adults, that number drops to around 5%.
Prevention
General Prevention Guidelines
Preventing hepatitis A . Wash hands thoroughly, especially after using the bathroom and before handling food. Be cautious with food and water when traveling to areas with higher hepatitis A risk. The is a reliable way to prevent infection, especially for people in high-risk groups.
Hepatitis B . Practice safe sex, don’t share personal items like razors or needles, and get tested during pregnancy to prevent newborn infections. The offers strong protection.
If you’ve been exposed to either virus, early intervention can prevent infection. For hepatitis A, this means getting the vaccine or immune globulin within two weeks. For hepatitis B, it usually involves the vaccine and possibly hepatitis B immune globulin—ideally within 24 hours.
History and Development of Available Vaccines
The hepatitis A vaccine was . Since universal childhood vaccination was recommended in 2006, hepatitis A cases in the U.S. dropped by 95%. Two vaccines— and —are approved in the U.S. and use inactivated virus to trigger immune protection.
The . The first version, made from human plasma, was licensed in 1981. A safer, genetically engineered version replaced it in 1986. This newer vaccine uses only a small part of the virus and cannot cause infection. It is more than 90% effective when the full vaccine series is completed.
There is also a combined vaccine, , that protects against both hepatitis A and B.
Current Vaccination Recommendations in the United States
The CDC :
- All children aged 12 to 23 months
- Unvaccinated children and teens ages 2 to 18
- Adults at higher risk, including international travelers, men who have sex with men, people who use drugs, those experiencing homelessness, individuals with HIV or chronic liver disease, and people with job-related risk
For hepatitis B, the CDC :
- All newborns, starting with a birth dose
- Unvaccinated people under age 19
- All adults ages 19 to 59
- Adults age 60 and older with risk factors
The hepatitis A vaccine is given in two doses, six months apart. The hepatitis B vaccine is usually given in three or four doses over a six-month period. Both provide long-term protection.
Conclusion
Hepatitis A and B both affect the liver but differ in how they spread, the symptoms they cause, and the risks they pose. Hepatitis A is almost always a short-term illness that clears on its own. Hepatitis B can become chronic and lead to serious health problems like liver damage or cancer. They are also the only two vaccine-preventable hepatitis viruses. Other viruses, like the (HCV), are not vaccine-preventable and pose their own public health and medical challenges.
Thanks to vaccines, these infections are now preventable. With routine childhood immunization and targeted adult vaccination, we’ve made major progress in reducing new cases. Testing and early diagnosis—especially for hepatitis B—are also key, since the disease often has no symptoms at first.
By understanding how these viruses work, taking preventive steps, and staying on top of medical care, we can protect ourselves and our communities from the serious consequences of hepatitis A and B.
Resources and Additional Reading
- Centers for Disease Control and Prevention.
- Centers for Disease Control and Prevention.
This page was updated in July 2025. For a previous version of the page, .