Aspirin is a widely used medication that is commonly used for pain relief, fever reduction, and as an anti-inflammatory drug. However, like all medications, aspirin can cause side effects in some people.

The most common side effect of aspirin is gastrointestinal irritation, which can cause stomach pain, nausea, and vomiting. Aspirin can also cause bleeding in the stomach and intestines, which can lead to more serious complications such as ulcers and perforations [1].

In addition to gastrointestinal problems, aspirin can also cause allergic reactions, which can range from mild skin rashes to severe anaphylaxis. Other potential side effects of aspirin include ringing in the ears, dizziness, and headache [2].

Aspirin should not be taken by children under the age of 16, as it has been linked to a rare but potentially life-threatening condition called Reye's syndrome. People who are allergic to aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) should also avoid taking aspirin [3].

It is important to note that these side effects are not experienced by everyone who takes aspirin, and most people can take aspirin safely without any problems. However, if you experience any of these side effects while taking aspirin, you should stop taking the medication and speak to your doctor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ASPIRIN
[2] https://www.nhsinform.scot/tests-and-treatments/medicines-and-medical-aids/types-of-medicine/aspirin
[3] https://www.drugs.com/aspirin.html