There is no universally recommended safe dosage of aspirin specifically for preventing ulcers, as the impact of aspirin on the stomach lining can vary from person to person. Regular use of aspirin can cause irritation in the stomach lining, potentially leading to ulcers [1]. However, aspirin is known to have certain benefits, such as reducing the risk of heart attacks and strokes in some individuals [1].

When it comes to aspirin dosage, the U.S. Food and Drug Administration (FDA) has approved aspirin for reducing the risk of heart attack and stroke in specific populations, such as those who have already experienced a heart attack or stroke, or those with certain heart conditions [1]. For this purpose, the FDA has approved dosages ranging from 75 to 325 milligrams per day [1].

The American Gastroenterological Association recommends that individuals who require aspirin for cardiovascular protection and are at risk for gastrointestinal complications take a proton pump inhibitor (PPI) or misoprostol to reduce this risk [2].

It is essential to consult a healthcare professional before starting or changing an aspirin regimen, as they can provide personalized advice based on an individual's medical history and current health status.

Sources:

1. U.S. Food and Drug Administration. (2014, March 1). FDA-Approved Patient Labeling - Aspirin Tablets, USP, 81 mg. Retrieved from <https://www.fda.gov/media/83241/download>
2. American Gastroenterological Association. (2021). AGA Guideline on Management of Antithrombotic-Related Bleeding in the GI Tract. Gastroenterology, 160(5), 1523-1537.e3. doi: 10.1053/j.gastro.2021.01.003. Retrieved from <https://www.gastrojournal.org/article/S0016-5085(21)00056-2/fulltext>
3. DrugPatentWatch.com. (n.d.). Aspirin. Retrieved from <https://www.drugpatentwatch.com/drugs/aspirin>