Aspirin can damage your stomach lining, and the risk is real even at low doses. Daily low-dose aspirin nearly doubles the risk of serious upper gastrointestinal bleeding in older adults, and the effect is not just a minor irritation. Understanding how this happens, who faces the greatest risk, and what you can do about it makes it possible to use aspirin more safely if you genuinely need it.
How Aspirin Damages the Stomach Lining
Your stomach protects itself from its own acid by producing a layer of mucus, and that mucus production depends on chemicals called prostaglandins. Aspirin shuts down the enzyme (COX-1) responsible for making those prostaglandins, and it does so permanently in every cell it reaches. Most pain relievers in the same family have a similar effect, but aspirin’s block is irreversible: once it hits a cell, that cell can’t produce protective prostaglandins again until your body replaces it with a new one.
This is why aspirin works so well for pain, fever, and preventing blood clots. It’s also why the stomach pays a price. With less mucus shielding the lining, stomach acid comes into direct contact with tissue it would normally never touch. The result can range from mild irritation and heartburn to erosions, ulcers, and bleeding.
Importantly, this damage is mostly systemic, meaning it happens because aspirin changes your body’s chemistry from the inside, not just because the pill sits in your stomach. That distinction matters when people assume a special coating on the tablet will solve the problem.
How Common Is Serious Bleeding?
The ASPREE trial, a large randomized study of over 19,000 healthy adults aged 70 and older, found that daily low-dose aspirin increased the risk of serious gastrointestinal bleeding by 60% compared to placebo. At an average follow-up of 4.7 years, participants showed higher rates of both upper and lower GI bleeding. For upper GI bleeding specifically, aspirin nearly doubled the risk.
People who already had additional risk factors for GI bleeding fared even worse. The risk wasn’t confined to people taking high doses or using aspirin recklessly. These were healthy older adults on 81 mg per day, the standard “baby aspirin” dose.
Factors That Raise Your Risk
Not everyone faces the same level of danger. Several things can compound aspirin’s effect on the stomach.
- Other pain relievers. Taking aspirin alongside another NSAID like ibuprofen or naproxen roughly triples the risk of upper GI bleeding compared to aspirin alone (relative risk around 2.6). Even moderate doses of these drugs create a significant increase.
- Blood thinners and corticosteroids. Combining aspirin with oral anticoagulants or high-dose corticosteroids raises the bleeding risk substantially. High-dose corticosteroids with aspirin carry a relative risk over four times that of aspirin alone.
- H. pylori infection. This common stomach bacterium, which many people carry without knowing it, increases the risk of peptic ulcers 3 to 5 times in aspirin users. Among people who are both H. pylori positive and taking aspirin, the risk of developing an ulcer is roughly 60 times higher than in someone who has neither risk factor.
- Age. Bleeding risk rises with age, which is one reason current guidelines from the U.S. Preventive Services Task Force recommend against starting aspirin for heart disease prevention in adults 60 and older.
Does Enteric Coating Help?
Enteric-coated aspirin is designed to dissolve in the intestine instead of the stomach, and many people buy it specifically hoping to avoid stomach problems. The evidence, however, is mixed at best. A systematic review found that while enteric coating may cause somewhat less direct mucosal damage than plain aspirin in the short term, it does not meaningfully reduce the risk of peptic ulcers or GI bleeding over time.
The reason goes back to how aspirin works. Because the damage is primarily systemic, it doesn’t matter much where the tablet dissolves. Once aspirin enters your bloodstream and blocks prostaglandin production throughout your body, your stomach lining loses its protection regardless of whether the pill dissolved in your stomach or further down the digestive tract. Enteric coating is not a reliable safeguard against serious complications.
What Actually Protects the Stomach
If you need to take aspirin long-term, the most effective strategy for reducing stomach damage is taking a proton pump inhibitor (PPI), the class of acid-reducing medications that includes omeprazole and lansoprazole. A meta-analysis found that PPIs reduced the risk of aspirin-associated stomach ulcers by about 84% and the risk of GI bleeding by about 73% compared to controls. PPIs also outperformed older acid blockers like famotidine for both ulcer and bleeding prevention.
Simpler precautions help too. The NHS recommends taking low-dose aspirin with food or just after eating rather than on an empty stomach. This won’t eliminate the systemic effects, but it reduces direct irritation and makes stomach upset less likely.
If you have risk factors for GI bleeding, particularly an H. pylori infection, getting tested and treated before starting long-term aspirin can dramatically lower your ulcer risk. Eradicating the bacteria removes one of the strongest multipliers of aspirin-related stomach damage.
Symptoms to Watch For
Aspirin-related stomach damage doesn’t always announce itself with obvious pain. The most common early signs are dyspepsia (a burning or uncomfortable feeling in the upper abdomen), bloating, nausea, and vomiting. Some people notice nothing at all until bleeding has already started.
Signs of GI bleeding include black, tarry stools, vomiting material that looks like coffee grounds, or feeling unusually tired and lightheaded without an obvious explanation. These warrant prompt medical attention. Even a mildly positive stool blood test in someone taking daily aspirin can signal erosion that could worsen.
Rethinking Routine Aspirin Use
For people who have already had a heart attack or stroke, the benefits of daily aspirin clearly outweigh the stomach risks. But for otherwise healthy people taking aspirin “just in case,” the math has shifted considerably. The U.S. Preventive Services Task Force now recommends against starting aspirin for heart disease prevention if you’re 60 or older, citing the bleeding risk. For adults 40 to 59 with elevated cardiovascular risk, the recommendation is neutral: the net benefit is small, and the decision should weigh individual bleeding risk.
The task force also suggests that people who are already on aspirin for prevention should consider stopping around age 75, when the bleeding risks continue to climb while the cardiovascular benefits diminish. If you’ve been taking a daily aspirin for years without a clear medical reason, it’s worth revisiting whether the tradeoff still makes sense for you.