Hepatitis B: Symptoms, Causes, Prevention, Diagnosis and Treatment
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). Most adults recover from short-term (acute) infection on their own, but the virus can become long-lasting (chronic), which raises the risk of liver scarring, liver cancer and liver failure. It spreads through blood, semen and other body fluids — not through sneezing or coughing — and a safe, effective vaccine can prevent infection. If you know you've been exposed, seek care right away: preventive treatment works best within 24 hours.
Quick Answer
What is hepatitis B? a liver infection caused by the hepatitis B virus (HBV), spread through blood, semen and other body fluids.
What are the main symptoms? abdominal pain, dark urine, fever, joint pain, loss of appetite, nausea, extreme tiredness and jaundice (yellowing of the skin and eyes).
How long does it last? acute infection lasts less than six months; chronic infection lasts six months or longer and can last a lifetime.
Is there a vaccine? yes — the hepatitis B vaccine is the main prevention, given at birth or as two to four shots over six months. You cannot get hepatitis B from the vaccine.
What happens after exposure? a shot of immunoglobulin within 24 hours, plus the vaccine, can help prevent infection.
How is chronic hepatitis B treated? long-term oral antiviral medicines, interferon injections in some cases, or a liver transplant if the liver is badly damaged.
Who is most at risk of chronic infection? infants and children under age 5 — most adults recover fully.
What Is Hepatitis B?
Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). The virus attacks liver cells and causes inflammation, which over time can lead to scarring and lasting damage.
For most people, hepatitis B is short term, a pattern doctors call acute hepatitis B. Acute infection lasts less than six months, and most adults recover fully even when symptoms are bad.
For others, the infection lasts more than six months and is called chronic. Chronic hepatitis B raises the risk of liver failure, liver cancer and cirrhosis — serious, permanent scarring of the liver that can stop it from working properly.
Hepatitis B is a liver infection that is usually acute and self-limiting in adults, but can become chronic — especially in infants and young children. A vaccine can prevent it, and the virus does not spread through casual contact like sneezing or coughing.
Three key facts frame how hepatitis B behaves. First, infants and children are far more likely than adults to develop chronic infection, which is why vaccination at birth matters so much. Second, the virus passes from person to person through blood, semen or other body fluids — it does not spread by sneezing or coughing, so ordinary social contact is not a risk. Third, treatment depends entirely on whether the infection is acute or chronic: some people need only time and self-care, while others need long-term medicine or, in advanced cases, a liver transplant.
What Are the Symptoms of Hepatitis B?
Symptoms of acute hepatitis B range from mild to serious. They usually start about one to four months after infection, though they can appear as early as two weeks afterward. Some people with acute or chronic hepatitis B never notice symptoms at all, especially young children — which is one reason screening matters even for people who feel well.
When symptoms do appear, they may include any of the following:
Pain in the stomach area (abdomen): discomfort where the liver sits, under the right ribcage
Dark urine: urine that looks tea- or cola-colored
Fever: a raised body temperature, often with tiredness
Joint pain: aching in the joints, a common viral response
Loss of appetite: little desire to eat
Upset stomach and vomiting: nausea that may come and go
Weakness and extreme tiredness: fatigue beyond normal daily tiredness
Jaundice: yellowing of the whites of the eyes and the skin — easier or harder to see depending on skin color
Hepatitis B can cause eight common symptoms, usually starting one to four months after infection. Eleven factors raise the risk of catching the virus, and anyone with a known exposure should seek preventive treatment within 24 hours.
A notable feature of hepatitis B is that symptoms can be completely absent. Young children often show no signs at all, and some adults with chronic infection never feel ill — even while the virus quietly damages the liver for decades.
When Should You See a Doctor?
Timing matters enormously with hepatitis B, and there is one situation that should trigger immediate action. If you know you have been exposed to the hepatitis B virus — for example, through an unprotected sexual encounter, a needlestick injury, or a known-positive partner — call a healthcare professional right away. A preventive treatment can lower your risk of infection, but it works best if given within 24 hours of exposure.
If you think you have symptoms of hepatitis B — abdominal pain, dark urine, fatigue or yellowing of the skin — call your healthcare professional rather than waiting to see whether symptoms pass. Jaundice in particular is a sign that the liver is under strain and should never be ignored.
What Causes Hepatitis B?
Hepatitis B is caused by the hepatitis B virus (HBV). The virus passes from person to person through blood, semen or other body fluids. Importantly, it does not spread by sneezing or coughing, through food or water, or through casual contact like hugging or sharing meals.
There are four common ways HBV spreads:
Sexual contact: having sex with an infected partner without a condom; the virus can pass through blood, saliva, semen or vaginal fluids
Sharing needles: needles and syringes tainted with infected blood; injecting illicit drugs with shared equipment
Accidental needlesticks: exposure for healthcare workers and anyone who comes into contact with human blood
Mother to newborn: during childbirth; the newborn can usually be vaccinated to prevent infection in almost all cases
Acute vs. Chronic Hepatitis B: What's the Difference?
The six-month mark divides the two forms of hepatitis B, and the difference determines everything about prognosis and treatment.
Duration: acute — less than six months. Chronic — six months or longer; may last a lifetime.
Outcome: acute — immune system usually clears the virus; full recovery within a few months. Chronic — immune system cannot clear the infection.
Who it affects most: acute — most adults infected with HBV. Chronic — infants and children under 5; some adults.
Symptoms: acute — often noticeable but temporary. Chronic — some people have none; others have ongoing tiredness and mild symptoms.
Long-term risk: acute — usually none after recovery. Chronic — cirrhosis, liver cancer and liver failure.
The younger you are when you catch hepatitis B, the higher the chance the infection becomes chronic. This is especially true for newborns and children younger than 5. Because chronic hepatitis B may not be detected for decades, some people do not learn they have it until they become very ill from liver disease.
What Factors Raise the Risk of Hepatitis B?
Your risk of HBV infection rises if you have any exposure to infected blood or body fluids. The following factors increase risk:
Sex without a condom with multiple partners or with someone infected with HBV
Sharing needles during drug injection
Sex between men (men born male who have sex with men)
Living with someone who has a chronic HBV infection
Being an infant born to an infected pregnant person
A job that exposes you to human blood (e.g., healthcare or emergency work)
Having hepatitis C or HIV
Receiving kidney dialysis
Being or having been in prison
Taking medicines that weaken the immune system, such as chemotherapy
Traveling to regions with high HBV rates: Asia, the Pacific Islands, Africa and Eastern Europe
What Complications Can Hepatitis B Cause?
Chronic HBV infection can lead to serious complications, which is why monitoring and treatment matter even when symptoms are mild.
The most significant complication is cirrhosis — scarring of the liver caused by ongoing inflammation, which may prevent the liver from working as it should. Chronic hepatitis B also raises the risk of liver cancer. When vital liver functions shut down entirely, the result is liver failure, which can only be survived with a liver transplant.
A lesser-known danger is reactivation. In some people with chronic hepatitis B, the virus stays at low or undetectable levels — but can suddenly begin copying itself rapidly. This reactivation can lead to liver damage or even liver failure, and it tends to affect people with weakened immune systems, such as those on high-dose corticosteroids or chemotherapy. If you are about to take medicines that suppress the immune system, you should be tested for hepatitis B first; if the test is positive, see a hepatologist (a doctor who specializes in liver disease) before starting treatment.
People with chronic hepatitis B may also develop other conditions, including kidney disease or inflammation of the blood vessels.
How Can Hepatitis B Be Prevented?
The hepatitis B vaccine is the main way to prevent infection — and the most important message for prevention is that you cannot get hepatitis B from the vaccine. Depending on the vaccine type, it is given as two shots one month apart, or three or four shots over six months.
Vaccination is recommended at birth for infants born to a mother who has tested positive or whose infection status is unknown. Babies who miss the birth dose should receive their first shot no earlier than two months of age, and parents can check antibody levels later to see whether additional shots are needed.
Everyone who was not vaccinated as a baby or child should be vaccinated through age 59. People aged 60 or older should get the vaccine if they are at risk of exposure, and those not at high risk can also choose to receive it.
The vaccine is strongly recommended for these groups:
Newborns
Children and adolescents not vaccinated at birth
People who work or live in centers for people with developmental disabilities
People who live with someone who has hepatitis B
Healthcare workers, emergency workers and anyone in contact with blood
Anyone with a sexually transmitted infection, including HIV
Men who have sex with men
People with multiple sexual partners
Sexual partners of someone who has hepatitis B
People who inject street drugs or share needles and syringes
People with chronic liver disease
People with end-stage kidney disease
Travelers to regions with a high HBV infection rate
Beyond vaccination, practical safety measures lower your risk considerably:
Know your sexual partner's HBV status: avoid unprotected sex unless you know your partner does not have hepatitis B or another STI
Use a new latex or polyurethane condom every time: lowers (but does not eliminate) risk when a partner's status is unknown
Avoid street drugs — and never share needles: use a sterile needle each time if you cannot stop; seeking help to quit is the safest path
Be cautious with piercings and tattoos: choose a reputable shop that uses sterile needles and can explain equipment cleaning
Ask about the vaccine before travel: a three-shot series over six months protects you in high-rate regions
How Is Hepatitis B Diagnosed?
A healthcare professional starts with a physical exam, looking for signs of liver damage such as yellowing skin and stomach pain. Three types of tests can confirm the diagnosis or assess complications:
Blood tests: detect the hepatitis B virus in your body, determine whether the infection is acute or chronic, and show whether you are already immune
Liver ultrasound (transient elastography): a special ultrasound that measures the amount of liver damage
Liver biopsy: a thin needle removes a small liver tissue sample through the skin for laboratory testing
Should Healthy People Be Screened?
Because HBV can damage the liver before symptoms appear, screening is sometimes recommended for people who feel entirely healthy. Talk with your healthcare professional about hepatitis B screening if you:
Are pregnant
Live with someone who has hepatitis B
Have had many sexual partners
Have had sex with someone who has hepatitis B
Are a man who has sex with men
Have a history of a sexually transmitted infection
Have HIV or hepatitis C
Have unexplained irregular liver enzyme results
Receive kidney dialysis
Take medicines that suppress the immune system, such as post-transplant drugs
Use injected street drugs
Are or have been in prison
Were born in (or have parents or adopted children from) regions where hepatitis B is common: Asia, the Pacific Islands, Africa and Eastern Europe
Pregnancy deserves special mention: pregnant people should be tested for hepatitis B because the virus can pass to the baby during childbirth, and the newborn can be vaccinated in almost all cases to prevent infection.
Diagnosis starts with blood tests that confirm the virus and classify the infection as acute or chronic. Treatment then follows one of three paths: self-care for acute cases, long-term antiviral therapy for chronic infection, or transplant for badly damaged livers. After an exposure, preventive treatment works best within 24 hours.
How Is Hepatitis B Treated?
Treatment depends on three different situations: after a fresh exposure, during an acute infection, and for chronic infection.
Treatment After Exposure
If you know you've been exposed to the hepatitis B virus, call a healthcare professional right away. The provider will ask when the exposure happened and what kind it was. A medicine called immunoglobulin — given by shot — may help protect you from getting sick, but it must be received within 24 hours of exposure. Because immunoglobulin provides only short-term protection, you should also receive the hepatitis B vaccine at the same time if you have never been vaccinated.
Treatment for Acute Hepatitis B
You might not need treatment at all for an acute infection — it is short-lived and most often goes away on its own. A healthcare professional will typically recommend rest, proper nutrition, plenty of fluids and close monitoring while your body fights the virus. If symptoms are severe, antiviral medicines or a hospital stay may be needed to prevent complications.
Treatment for Chronic Hepatitis B
Most people with chronic hepatitis B need treatment for the rest of their lives. The decision to start treatment depends on whether the virus is causing inflammation or cirrhosis, whether you have other infections such as hepatitis C or HIV, and whether your immune system is weakened. Treatment lowers the risk of liver disease and also prevents you from passing the infection to others.
Antiviral medicines (oral): fight the virus and slow its ability to damage the liver; include entecavir, tenofovir, lamivudine and adefovir. Taken by mouth, usually long-term; two medicines may be combined, or one may be combined with interferon.
Interferon injections: a lab-made version of a substance your body produces to fight infection; example: peginterferon alfa-2a. Shorter treatment than oral antivirals, but a higher rate of side effects (upset stomach, vomiting, trouble breathing, depression); mainly for younger patients and women planning pregnancy in a few years; not suitable during pregnancy or for people with cirrhosis.
Liver transplant: the damaged liver is removed and replaced with a healthy one. For badly damaged livers; most donor livers come from deceased donors, some from living donors.
Other medicines to treat hepatitis B are currently in development.
Living With Hepatitis B: Lifestyle and Self-Care
If you have hepatitis B, your day-to-day choices affect both your liver and the people around you. If you are sexually active, tell your partner you have HBV, discuss the risk of transmission, and use a new latex condom every time — condoms lower the risk but do not eliminate it. Anyone you've had sex with should be tested, because partners need to know their own HBV status to avoid infecting others.
Never share needles or syringes, and do not share razor blades or toothbrushes, which can carry traces of infected blood. To protect your liver itself, avoid alcohol, do not start new medicines without talking with your healthcare professional, get tested for hepatitis A and C, and get vaccinated against hepatitis A if you have not already been exposed.
Coping is also easier when you stay connected. Because hepatitis B cannot be spread through casual contact, there is no reason to isolate yourself from friends and family — support from loved ones genuinely helps. A healthy diet full of fruits and vegetables, regular exercise and enough sleep round out the picture.
Preparing for Your Appointment
You are likely to start by seeing your family healthcare professional, who may refer you to a specialist — a gastroenterologist (digestive diseases), a hepatologist (liver diseases) or an infectious disease doctor.
Before your visit, note any pre-appointment restrictions such as diet limits, write down all your symptoms (even ones that seem unrelated), list key personal stresses or life changes, bring a complete list of medicines, vitamins and supplements with doses, and take a family member or friend along to help remember what the team says.
Useful questions to ask your healthcare professional include:
What is likely causing my symptoms or condition?
What other causes could explain my symptoms?
What tests do I need?
Is my condition likely short- or long-term?
Has hepatitis B damaged my liver or caused other complications, such as kidney problems?
What is the best course of action?
Are there treatment choices aside from the main one suggested?
How can I manage my other health conditions alongside this?
Are there restrictions I need to follow?
Should I see a specialist?
Should my family be tested for hepatitis B?
How can I protect people around me from HBV?
Expect your provider to ask about when your symptoms started, whether you've ever had jaundice or clay-colored stool, whether you've been vaccinated, and how often and how severely symptoms occur.
Bottom Line
Hepatitis B is a serious but highly preventable liver infection. Most adults clear acute infections on their own, but chronic hepatitis B requires long-term attention because of its links to cirrhosis, liver cancer and liver failure. The single most important actions are getting vaccinated — the vaccine is safe and works — and acting fast after any known exposure, when preventive treatment is most effective within 24 hours.
Your next step: If you're unsure of your vaccination status or whether you should be screened, book an appointment with your healthcare professional this month. If you've had a possible exposure recently, call right away — that 24-hour window makes all the difference.
Explore more of our liver health guides: fatty liver disease (MASLD) and how it's tested and treated and H. pylori infection, the stomach germ that can also affect your gut health.
Frequently Asked Questions
Can hepatitis B go away on its own?
Yes, in most cases. Acute hepatitis B lasts less than six months, and most adults recover fully even when symptoms are severe. The risk of the infection becoming chronic is highest for infants and children under age 5.
Is there a cure for chronic hepatitis B?
Most people with chronic hepatitis B need lifelong treatment with antiviral medicines such as entecavir or tenofovir. Treatment does not always eliminate the virus completely, but it slows liver damage and reduces the chance of passing the infection to others.
How do you catch hepatitis B?
The virus spreads through blood, semen and other body fluids — most commonly through unprotected sex, sharing needles, needlestick injuries, and from an infected pregnant person to a newborn during childbirth. It does not spread by sneezing, coughing, or casual contact.
Can you get hepatitis B from the vaccine?
No. The hepatitis B vaccine cannot give you hepatitis B. Depending on the vaccine type, it involves two shots one month apart or three to four shots over six months.
What should I do if I'm exposed to hepatitis B?
Call a healthcare professional right away. A shot of immunoglobulin given within 24 hours of exposure, combined with the vaccine if you're not already vaccinated, can help prevent infection.
How is hepatitis B different from hepatitis A or C?
The virus types differ and so do transmission patterns and vaccines. A safe vaccine exists for hepatitis B (and for hepatitis A), and a blood test can confirm which type of infection — if any — you have.
Can hepatitis B cause liver cancer?
Yes. Chronic hepatitis B raises the risk of liver cancer, cirrhosis (severe liver scarring) and liver failure. This is why long-term monitoring and treatment matter even when symptoms are mild or absent.
Is hepatitis B contagious through kissing or sharing food?
No. The virus does not spread through casual contact such as sneezing, coughing, hugging, sharing meals, or kissing in everyday social situations. Transmission requires exposure to blood, semen or other body fluids.
References
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. This article reflects medical guidance current as of January 14, 2026.
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