Causes and Risk Factors of Gastritis

Gastritis causes inflammation of the stomach lining (known as the mucosa). The stomach’s lining protects it from digestive acids and potentially harmful microbes, such as bacteria. Irritation or damage to this lining can cause inflammation, leading to gastritis. The most common causes include an H. pylori infection, alcohol consumption, and autoimmune disorders.

Gastritis can either develop suddenly and last briefly or progress slowly and persist for months or years. Many people with gastritis do not develop symptoms and are unaware they have it. When symptoms develop, gastritis causes indigestion, abdominal pain, nausea or vomiting, loss of appetite, and unintended weight loss. Chronic gastritis can lead to more severe symptoms, like stomach ulcers or tarry stools. 

Knowing the cause of your symptoms can help your healthcare team identify which type of gastritis you have and recommend a treatment plan that offers symptom relief.

The leading cause of gastritis is a Helicobacter pylori (H. pylori) infection. Evidence suggests the bacteria spreads through contact with the body fluids (e.g., saliva) of a person with the infection or through consumption of contaminated food and water.

About half of the world’s population lives with an H. pylori infection, most developing it during childhood. When H. pylori infects the stomach, it can cause inflammation and damage to the stomach lining, leading to gastritis. While H. pylori nearly always causes gastritis, only 20% of those with the infection develop gastritis symptoms or complications. 

Long-term or excessive use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as Advil and Motrin (ibuprofen), Aleve (naproxen), or Bayer (aspirin), can weaken and damage the stomach’s protective mucosal layer, leading to gastritis.

NSAIDs inhibit the production of prostaglandins, which help regulate stomach acid production and protect the lining. By reducing prostaglandin levels, NSAIDs can weaken the stomach’s natural defenses against digestive acids. This can lead to chronic inflammation, stomach ulcers, or bleeding over time.

Prolonged or excess alcohol use can irritate and erode (damage) the stomach’s protective lining, which shields it from digestive acids. When this barrier is weakened, the stomach lining becomes inflamed and vulnerable to damage, leading to gastritis.

Alcohol can also stimulate the stomach to produce more gastric (digestive) acid than usual, further irritating the stomach lining and increasing the risk of gastritis and ulcers. Over time, heavy alcohol consumption can impair the stomach’s ability to heal from minor injuries or inflammation, increasing the risk of chronic gastritis. 

Autoimmune gastritis develops when your immune system mistakenly attacks the stomach lining, targeting and destroying parietal cells. These cells play a role in producing stomach acid and intrinsic factor, a protein that is essential for absorbing vitamin B12 from the foods you eat. 

As the immune system mistakenly destroys parietal cells, the stomach produces less gastric acid, leading to digestive problems and increasing the risk of stomach infections. The loss of parietal cells also affects the production of intrinsic factor, making it harder for the body to absorb vitamin B12 and increasing the risk of anemia. 

The risk of autoimmune gastritis is higher in people with underlying autoimmune disorders, such as type 1 diabetes, thyroid disease (e.g., Hashimoto’s thyroiditis), Addison’s disease, vitiligo, and chronic spontaneous urticaria. 

Gastritis can also develop in response to major health events or traumas that cause stress, such as:

• Severe injuries or burns
• Major surgeries
• Critical illnesses, like sepsis or heart attack
• Prolonged stays in an intensive care unit (ICU) on a ventilator 

Under extreme stress, your body reduces blood flow to the stomach, depriving its tissues of oxygen and nutrients and weakening its protective lining, making it more vulnerable to acid damage. Stress can also trigger an increase in stomach acid production. When the stomach lining is weak, this excess acid can easily irritate and inflame the lining, leading to gastritis.

Most forms of gastritis are not hereditary. However, ongoing research suggests genetics may contribute to autoimmune gastritis, which occurs when the immune system mistakenly attacks the stomach lining.

People with a family history of autoimmune disorders, such as autoimmune thyroid disease or type 1 diabetes, are more likely to develop this type of gastritis. Genetic mutations (changes) in several genes, some of which regulate stomach acid production and the immune system, may also increase the risk of autoimmune gastritis. 

More research is still needed to fully understand how genetic variants contribute to the onset and progression of gastritis. There is no clear evidence that genetics influence other forms of gastritis besides autoimmune gastritis. 

An estimated 20% of people will develop gastritis at some point, and some are more likely to develop it than others. Consider these risk factors:

• Age: Gastritis can occur at any age, but it is more common in older adults. People assigned female at birth are more likely to develop gastritis from ages 45-64, while people assigned male at birth are more likely to experience gastritis after 65. 
• Sex: Evidence suggests people assigned female at birth have a slightly higher risk of experiencing gastritis in comparison to their male counterparts. 
• Ethnicity: People of all ethnic backgrounds can develop gastritis, but in the United States, H. pylori infection, a leading cause of gastritis, tends to be more common in Indigenous and Hispanic communities.

Several other factors can also increase your likelihood of developing gastritis. These include:

• Geography: Living in regions with poor sanitation and crowded living situations can increase the risk of developing H. pylori infections.
• Tobacco use: Smoking can stimulate excess acid production in the stomach and increase the risk of gastritis. 
• Emotional stress: While physical stress from injuries and surgeries can cause gastritis, untreated emotional stress and trauma (such as major depressive disorder) can also increase your risk of gastritis. 

Gastritis, or inflammation of the stomach lining, has several possible causes. The most common causes include an H. pylori infection, long-term use of NSAIDs, excess alcohol consumption, physical stress, and autoimmune disorders. Anyone can develop gastritis, but older adults and people assigned female at birth have a higher risk of experiencing symptoms.