Even if none of these conditions is present, the risk of stomach bleeding is still increased when aspirin is taken with alcohol or warfarin. People with hemophilia or other bleeding tendencies should not take aspirin or other salicylates. Aspirin is known to cause hemolytic anemia in people who have the genetic disease glucose-6-phosphate dehydrogenase deficiency, particularly in large doses and depending on the severity of the disease. Use of aspirin during dengue fever is not recommended owing to increased bleeding tendency. People with kidney disease, hyperuricemia, or gout should not take aspirin because it inhibits the kidneys ability to excrete uric acid, thus may exacerbate these conditions. Aspirin should not be given to children or adolescents to control cold or influenza symptoms, as this has been linked with Reyes syndrome. Gastrointestinal
Aspirin use has been shown to increase the risk of gastrointestinal bleeding. Although some enteric-coated formulations of aspirin are advertised as being "gentle to the stomach", in one study, enteric coating did not seem to reduce this risk. Combining aspirin with other NSAIDs has also been shown to further increase this risk. Using aspirin in combination with clopidogrel or warfarin also increases the risk of upper gastrointestinal bleeding.Blockade of COX-1 by aspirin apparently results in the upregulation of COX-2 as part of a gastric defense. Several trials suggest that the simultaneous use of a COX-2 inhibitor with aspirin may increase the risk of gastrointestinal injury. However, currently available evidence has been unable to prove that this effect is consistently repeatable in everyday clinical practice.
The United States Preventive Services Task Force (USPSTF), in 2016, recommended initiating low-dose aspirin use for the primary prevention of cardiovascular disease and colon cancer in adults aged 50 to 59 years who have a 10% or greater 10-year cardiovascular disease (CVD) risk, are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years. However, in 2021, the USPSTF recommended against the routine use of daily aspirin for primary prevention in adults in their 40s and 50s, citing the fact that the risk of side effects outweighs the potential benefits. In April 2022, the USPSTF said "people ages 40 to 59 who are at higher risk for CVD should decide with their clinician whether to start taking aspirin; people 60 or older should not start taking aspirin to prevent a first heart attack or stroke. "The status of the use of aspirin for the primary prevention in cardiovascular disease is conflicting and inconsistent. The ASCEND study demonstrated that in high-bleeding risk diabetics with no prior cardiovascular disease, there is no overall clinical benefit (12% decrease in risk of ischaemic events v/s 29% increase in GI bleeding) of low dose aspirin in preventing the serious vascular events over a period of 7.4 years.