Causes and Risk Factors of Hepatitis

Several things can cause hepatitis, including microbes, harmful substances, and medical conditions. The most common form of hepatitis is viral hepatitis, brought on by viruses hepatitis B and C. Other causes of hepatitis include toxic substances (ex. alcohol or drugs) and autoimmune diseases.

Common Causes

While hepatitis viruses are the most common cause of hepatitis, certain medical conditions, medications, or drugs can lead someone to develop it, too.

Viral Hepatitis

Viral hepatitis is the most common type of hepatitis, and it’s primarily caused by five viruses: hepatitis A, B, C, D, and E. All of these viruses can affect the liver, but some are more serious than others, and they can be spread in different ways.

• Hepatitis A Virus: People become infected with hepatitis A virus (HAV) when they come into contact with food or water contaminated with the virus, or through sexual activity. While HAV infections can be serious, most cases clear up on their own.
• Hepatitis B Virus: Type B (HBV) spreads through bodily fluids like blood or semen. As a result, most new infections happen because of sexual contact or sharing needles, though moms can also pass on the virus to their baby during childbirth. Those with HBV infections don’t always have symptoms, and some can go on to have lifelong infections that lead to serious health conditions like liver cancer. Chronic infections are more common in young infants. Approximately 90% of infants with HBV develop chronic infections, compared to roughly 5% of infected adults.
• Hepatitis C Virus: While some hepatitis C (HCV) infections are only temporary (or “acute”), the majority (75% to 85%) of people with acute hepatitis C will develop chronic hepatitis C. Like HBV, HCV can be spread by contaminated needles used by drug users or in healthcare settings, from mother to child during birth or, less commonly, through sexual contact or other activities. 
• Hepatitis D Virus: Commonly referred to as “delta hepatitis,” type D (HDV) is spread through contact with an infected person’s blood or other body fluids. It can only infect you when you also have HBV.
• Hepatitis E Virus: Hepatitis E virus (HEV) is similar to HAV in that it is spread through contaminated food or water (often because of poor sanitation). It is more common in developing countries, where access to clean water is limited. While experts used to think hepatitis E was rare in the United States, recent research suggests that about 20% of the population has had hepatitis E.

Some researchers think other viruses (not listed above) might also cause hepatitis, but so far no more microbes have been clearly linked to the condition.

Toxic Hepatitis

Toxic hepatitis is when substances damage the liver and cause it to swell. The primary drivers behind toxic hepatitis are alcohol, toxic chemicals, and certain medications.

Alcohol: Alcohol’s damaging impact on the liver is well documented, and alcoholic hepatitis is just one of many harmful conditions that can come as a result of long-term or heavy drinking.

Chemicals: Repeated or excessive exposure to toxic chemicals like solvents or other organic chemicals can lead to toxic hepatitis, whether it be by ingesting, touching or breathing in the substances.

Drugs: Some over-the-counter and prescription medications can cause toxic hepatitis, including:

• Amiodarone
• Amoxicillin-clavulanate
• Anabolic steroids
• Birth control medications
• Chlorpromazine
• Erythromycin
• Halothane
• Isoniazid
• Methyldopa
• Methotrexate
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Statins
• Sulfa drugs
• Tetracyclines
• Some anti-seizure medications

In some cases, use of the above medications (especially in high doses) might trigger hepatitis in people who are already susceptible, such as those with other underlying liver disease.

Autoimmune Hepatitis

Autoimmune hepatitis is when your own body’s defenses attack your liver, causing it to swell and become damaged. It’s unclear exactly what causes autoimmune hepatitis, but researchers think both genes and environmental factors (like medications or viruses) could play a role. Approximately 70% of people with autoimmune hepatitis are women, typically between the ages of 15 and 40. Many people with this disease also have other autoimmune diseases, including type 1 diabetes, thyroiditis, ulcerative colitis, vitiligo, or Sjögren’s disease.  

Lifestyle Risk Factors

Some things can increase your chances of developing hepatitis, including certain environmental factors, behaviors or health issues.

Environmental Risk Factors

Because many causes of hepatitis are found in a person’s surroundings, exposure to certain environmental factors can make you more likely to develop hepatitis over time. Environmental risk factors associated with hepatitis include:

• Unsafe water for drinking or washing produce
• A lack of sanitation services like bathrooms or places to wash hands
• Contact with used needles, syringes, or other objects that might be contaminated with blood infected with hepatitis viruses

Behavioral Risk Factors

Likewise, some behaviors or activities can make it more likely you’ll be exposed to viruses, toxic chemicals or substances that cause hepatitis. Behaviors that increase a person’s chances of developing hepatitis include:

• Sharing needles or other objects (such as straws if inhaling drugs) that might be contaminated with hepatitis viruses
• Condomless sex, having multiple sex partners, or other sexual practices that increase potential exposure
• Working around toxic chemicals. Examples of occupations routinely exposed to such chemicals include dry cleaners, painters, healthcare providers, or farm workers.
• Drinking untreated water or eating food that has not been safely or properly prepared (ex. unwashed produce)
• Drinking large quantities of alcohol over a long period of time
• Taking medications believed to be linked to hepatitis

Health Risk Factors

A person’s health history might also affect the chances he or she will develop hepatitis.

Health risk factors for hepatitis include:

• Not being vaccinated against viral hepatitis, specifically HAV and HBV (there is no vaccine for HBC)
• Having an acute or chronic infection with one or more hepatitis viruses
• Having an autoimmune disorder, such as autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECE) 
• Being born to a mother who is infected with a hepatitis virus, particularly hepatitis B

Your healthcare provider will be able to discuss with you the specific steps you can take to reduce your chances of developing hepatitis or other liver conditions.