Hepatitis means inflammation of the liver. There are many causes of hepatitis. Some cases are mild, but hepatitis can be life-threatening.

In humans, the liver is a large organ found on the right side of the upper abdomen, protected by the ribcage. We cannot live without a liver because it performs hundreds of important functions.

The liver filters the blood and removes waste products from the body. Alcohol, drugs (legal and illegal, over-the-counter and prescription) and poisonous chemicals are metabolized and detoxified by the liver. It stores vitamins, minerals and energy for the body. It regulates many hormones, makes blood clot appropriately, helps the body fight infection, produces bile to digest our food and regulates cholesterol levels.

If the liver is inflamed, it cannot function properly. Symptoms of all types of hepatitis include fatigue, abdominal pain, nausea, vomiting, loss of appetite, diarrhea, dark urine, fever, headache and jaundice (yellowing of the skin and eyes). Sometimes, hepatitis has no obvious symptoms.

There are at least five known types of viruses that cause hepatitis: A, B, C, D and E. There are probably more hepatitis viruses that have not yet been identified. These tiny viruses enter the body and affect the liver in different ways.

Hepatitis A is spread through food or water contaminated by the feces of an infected person. Although it can make a person quite sick, it usually resolves without treatment after several weeks. Once someone has had hepatitis A, they are immune and cannot be infected again.

Hepatitis B is transmitted by contact with infected blood or by having sex with an infected person. Some people recover from a hepatitis B infection, but others develop a chronic form of hepatitis, which can cause liver cancer.

Hepatitis C spreads through contact with infected blood; less commonly it can spread through sexual contact. Hepatitis C is similar to Hepatitis B in that it can lead to liver cancer.

Hepatitis D occurs only in people who are already infected with Hepatitis B; it spreads through contact with infected blood. Hepatitis D is a chronic infection.

Hepatitis E is spread through food or water contaminated by feces of an infected person. This virus is more common in developing countries; it is rare in the United States. The infection resolves without treatment in a few months.

Vaccines can prevent hepatitis A and B. Children in the United States usually get the hepatitis B vaccine in infancy. Hepatitis A vaccine is primarily given to international travelers, but since Oregon and Washington have high hepatitis A rates compared to other states, children here should get the vaccine.

Hepatitis can also be caused by chemical toxins that are consumed or inhaled, such as alcohol, drugs, industrial solvents and poisonous mushrooms. Common medications such as acetaminophen (Tylenol) can cause toxic hepatitis, especially if an overdose is taken.

Any type of chronic hepatitis will eventually cause cirrhosis of the liver. With cirrhosis, scar tissue replaces normal tissue in the liver, so blood cannot flow normally. The liver is unable to work properly. Damage from cirrhosis cannot be reversed, but treatment can slow the damage.

Hepatitis is diagnosed with blood tests. A biopsy of the liver may be needed to determine the severity of the damage.

Kathryn B. Brown is a family nurse practitioner with a master’s degree in nursing from OHSU.