Low-dose aspirin (LDA) is typically prescribed for the long-term prevention of cardiovascular events like heart attacks and strokes. This daily regimen helps inhibit blood clotting, but even at low doses, aspirin can irritate and damage the delicate lining of the gastrointestinal (GI) tract. Understanding the relationship between LDA and stomach health is important for individuals weighing the benefits against the risks of GI complications.
How Aspirin Damages the Stomach Lining
Aspirin harms the stomach through two mechanisms: one local and one systemic. Locally, aspirin is an acidic compound that directly irritates the mucosal cells of the stomach upon contact. This chemical injury can cause irritation of the stomach lining as the tablet dissolves.
The systemic damage stems from aspirin’s action as a cyclooxygenase (COX) inhibitor. Aspirin blocks the activity of the COX-1 enzyme, which produces signaling molecules called prostaglandins. Prostaglandins protect the stomach by regulating the secretion of bicarbonate and mucus, and by maintaining blood flow to the gastric lining.
By blocking COX-1, aspirin removes this natural protective shield, leaving the stomach vulnerable to its highly acidic environment. This systemic effect means that even formulations designed to protect the stomach from local irritation, such as enteric-coated tablets, do not eliminate the overall risk of GI damage.
Types of Gastrointestinal Complications
The damage caused by low-dose aspirin ranges from minor discomfort to serious bleeding events. The most common issues are generally mild, including dyspepsia (indigestion, heartburn, or general stomach upset). This irritation, known as gastritis, involves inflammation of the stomach lining and is the most frequent complaint among chronic aspirin users.
More significant damage involves the formation of erosions and ulcers, which are open sores that develop in the lining of the stomach or the duodenum. Low-dose aspirin use is associated with an increased risk of peptic ulcers. These ulcers can be small and asymptomatic, but they represent a breakdown in the mucosal barrier.
The most serious complication is gastrointestinal bleeding, which can occur in either the upper or lower GI tract. Bleeding can be acute and severe, presenting with symptoms like vomiting blood or passing black, tarry stools. It can also be chronic and slow, leading to iron-deficiency anemia over time. Even at low doses, aspirin increases the risk of serious GI bleeding by affecting the clotting process.
Who Is Most Vulnerable to Stomach Problems
Several factors increase a person’s vulnerability to developing GI complications while taking low-dose aspirin. Advanced age is a risk factor, with individuals over 60 having a higher risk of bleeding events. A prior history of a peptic ulcer or GI bleeding also raises the likelihood of recurrence when taking LDA.
The concurrent use of certain medications multiplies the risk. Taking other nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, alongside aspirin increases the risk of upper GI bleeding. Similarly, the simultaneous use of anticoagulants or corticosteroids elevates the risk of bleeding.
An existing infection with Helicobacter pylori (H. pylori) also predisposes the stomach to ulceration. This bacterium weakens the mucosal defense, and when combined with aspirin, the risk of developing a bleeding ulcer is compounded. Addressing existing H. pylori infection is often part of the risk mitigation strategy.
Reducing the Risk of GI Side Effects
For individuals who need to take low-dose aspirin, several strategies help mitigate the risk of GI side effects. A simple step is to take the aspirin with food or a full glass of water, which buffers the acidity and minimizes the local irritant effect. Patients should also avoid the concomitant use of other NSAIDs unless advised by a healthcare provider.
Some patients are prescribed an enteric-coated aspirin formulation, designed to prevent the tablet from dissolving until it reaches the small intestine. While this coating reduces local irritation, it does not eliminate the systemic risk of bleeding or ulceration caused by the drug’s effect on prostaglandins.
For those identified as high-risk, a physician may co-prescribe a gastroprotective agent, such as a proton pump inhibitor (PPI) or an H2 blocker. PPIs effectively reduce stomach acid production, protecting the lining from acid damage. Discussing risk factors with a healthcare professional is essential before starting or stopping any aspirin regimen.