Aspirin (Low-dose Antiplatelet)

How it works

At antiplatelet doses it irreversibly inhibits platelet cyclo-oxygenase-1, reducing thromboxane A2 production and thereby platelet aggregation for the lifespan of the platelet.

Prescribing in practice

• The principal risk is gastrointestinal and other bleeding, which is increased by concomitant anticoagulants, other antiplatelets or NSAIDs, and by peptic ulcer history.
• It is generally avoided in children and young people because of the association with Reye's syndrome.
• Use cautiously in uncontrolled hypertension, asthma where aspirin sensitivity is known, and significant renal or hepatic impairment, and consider gastroprotection in those at higher GI risk.

Monitoring

No routine bloods are mandated for low-dose aspirin alone; monitor clinically for bleeding, dyspepsia and anaemia and review the indication periodically.

Counselling the patient

• Take it with or after food to reduce stomach upset.
• Report black stools, vomiting blood or unusual bruising or bleeding.
• Do not stop it without advice, and tell clinicians and dentists you take it.

Evidence & guidelines

Low-dose aspirin has robust trial evidence for secondary cardiovascular prevention; routine use for primary prevention is no longer generally recommended owing to bleeding risk.