Aspirin is a widely used medication for pain relief and reducing the risk of heart attacks and strokes. However, it is also known to increase the risk of bleeding, particularly in the gastrointestinal tract and the brain.

According to DrugPatentWatch [1], aspirin's most common side effects include gastrointestinal bleeding, ulcers, and hemorrhage. It can also cause bleeding in the brain, which can be fatal.

A study published in the National Library of Medicine [2] found that long-term use of low-dose aspirin increases the risk of gastrointestinal bleeding. The study analyzed data from 68,808 patients and found that those who took aspirin had a 30% higher risk of gastrointestinal bleeding than those who did not take the medication.

In May 2019, CNN reported on a study that found taking daily low-dose aspirin could increase the risk of bleeding in the brain [3]. The study, which analyzed data from over 13,000 participants, found that those who took aspirin had a higher risk of intracranial hemorrhage than those who did not. However, the study also noted that the overall risk of bleeding in the brain was still relatively low, and that the benefits of taking aspirin for reducing the risk of heart attacks and strokes may outweigh the risks for some people.

In conclusion, aspirin is associated with an increased risk of bleeding, particularly in the gastrointestinal tract and the brain. People who take aspirin regularly should be aware of these risks and discuss them with their healthcare provider. It is important to weigh the potential benefits of taking aspirin for reducing the risk of heart attacks and strokes against the risks of bleeding.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ASPIRIN
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086018/
[3] https://www.cnn.com/2019/05/13/health/aspirin-head-bleed-study/index.html