Acetylsalicylic acid, commonly known as aspirin, is a widely available over-the-counter medication primarily used for pain relief, fever reduction, and its antiplatelet properties. When the COVID-19 pandemic began, its potential role in managing the virus’s severe complications became a significant subject of medical research. The interest stemmed from the unique way the SARS-CoV-2 virus affects the body’s vascular system, prompting investigators to explore whether this affordable drug could offer therapeutic benefits against the infection’s life-threatening effects.
The Connection Between COVID-19 and Blood Clotting
The reason aspirin became a therapeutic candidate is rooted in the underlying pathophysiology of severe COVID-19 infection. The virus triggers heightened inflammation, leading to COVID-19-associated coagulopathy (CAC), which involves the immune system and the body’s clotting mechanisms. The infection causes endothelial dysfunction, damaging the inner lining of blood vessels and promoting platelet activation. This leads to a pro-thrombotic state, resulting in microclots within the lungs and larger thrombotic events, such as pulmonary embolisms or strokes, which cause morbidity and mortality in severe cases.
Aspirin functions as an antiplatelet agent by irreversibly inhibiting the enzyme cyclooxygenase-1 (COX-1), which is necessary for platelet aggregation. By making platelets less “sticky,” low-dose aspirin (typically 81 mg) acts as a “blood thinner” to prevent these dangerous clots from forming. This mechanism provided a strong theoretical basis for using the drug to mitigate the severe thrombotic complications observed in hospitalized COVID-19 patients.
Current Medical Guidance on Aspirin Use for COVID-19
Initial observational studies suggested a possible benefit, indicating that hospitalized patients taking low-dose aspirin had a lower risk of mechanical ventilation and death. However, these early findings were not consistently supported by larger randomized controlled trials (RCTs). For instance, the large-scale RECOVERY trial found no significant reduction in mortality among hospitalized patients.
For patients managing the illness at home (outpatients) with mild to moderate symptoms, aspirin is not recommended for routine use to treat or prevent COVID-19 progression. The NIH COVID-19 Treatment Guidelines panel does not recommend starting aspirin solely for COVID-19 in outpatients due to insufficient data and the risk of bleeding.
For hospitalized patients, the guidance is more nuanced and focused on anticoagulation with other agents. Patients already taking aspirin for a pre-existing medical condition, such as heart disease or stroke, should generally continue their therapy. However, starting aspirin as a new treatment for all hospitalized COVID-19 patients is not the current standard of care, as robust RCT data indicates it significantly increases the risk of bleeding events without reducing mortality or thrombosis.
Risks and Contraindications of Aspirin Therapy
Despite its over-the-counter availability, aspirin is a powerful medication with significant risks, particularly when taken without medical supervision. The primary adverse effect is an increased risk of bleeding, ranging from minor bruising to severe gastrointestinal hemorrhage. This risk is amplified in individuals who are older, consume alcohol regularly, or are taking other blood-thinning medications.
Aspirin can also cause stomach ulcers and worsen existing conditions like asthma. A serious, albeit rare, contraindication is Reye’s syndrome, a life-threatening condition involving swelling in the liver and brain. Because of this risk, aspirin is strongly advised against for children and adolescents recovering from a viral illness.
Individuals with active peptic ulcer disease, known bleeding disorders like hemophilia, or severe liver disease should also avoid aspirin. Any decision to begin aspirin therapy requires a careful assessment of the individual’s overall health and bleeding risk by a healthcare provider.