Aspirin Prescription Errors: Could a New Blood Test Make Daily Aspirin Safer?

Aspirin is one of the oldest and most familiar medicines in the world. Yet the way it is used to prevent heart attacks has changed considerably over recent years.

For decades, low-dose aspirin was prescribed to many people thought to be at increased risk of heart attack or stroke. Aspirin is sometimes described as a “blood thinner”, although technically it is an antiplatelet medicine. It interferes with the ability of platelets to stick together, helping to reduce the formation of potentially dangerous blood clots.

The problem is that the same mechanism which can prevent a heart attack can also increase the risk of bleeding.

That has created a difficult clinical balance: for one patient aspirin may be potentially life-saving, while for another the bleeding risk may outweigh the cardiovascular benefit.

Now researchers are investigating whether a relatively quick blood test could help doctors identify that difference.

Why is aspirin prescribed to prevent heart attacks?

The NHS guidance on aspirin explains that low-dose aspirin can be used to prevent blood clots and reduce the risk of heart attack and stroke.

Low-dose aspirin is commonly 75mg in the UK.

When a blood vessel is damaged, platelets become activated and stick together. This is an essential part of stopping bleeding, but inappropriate clot formation within an artery can obstruct the blood supply to the heart or brain.

Aspirin reduces platelet activity.

This explains why aspirin remains particularly important for some people who have already suffered a heart attack or stroke or have established cardiovascular disease.

The position is very different when aspirin is being considered simply to prevent a first cardiovascular event.

Why did doctors stop routinely prescribing daily aspirin to otherwise healthy people?

The balance between benefit and harm became increasingly clear as larger clinical trials were completed.

In 2023, the National Institute for Health and Care Excellence (NICE) introduced a clear recommendation:

Do not routinely offer aspirin for primary prevention of cardiovascular disease.

The distinction between primary and secondary prevention is important.

Primary prevention means trying to prevent someone’s first cardiovascular event. Secondary prevention concerns people who have already developed cardiovascular disease or suffered an event such as a heart attack.

Research has demonstrated why treating these two groups in the same way can be problematic.

A major 2019 systematic review and meta-analysis published in JAMA examined 13 clinical trials involving 164,225 people without known cardiovascular disease.

Aspirin was associated with a reduction in cardiovascular events, but also an increase in major bleeding. The absolute reduction in cardiovascular events was approximately 0.41%, while the absolute increase in major bleeding was approximately 0.47%.

In other words, prescribing aspirin to everybody considered at risk is not necessarily the straightforward preventative measure it might initially appear.

Could personalised aspirin treatment change this?

Potentially.

New research being developed by scientists connected with the University of Reading and spin-out company HaemAnalytica is exploring whether platelet behaviour can be assessed to predict how individual patients will respond to antiplatelet medication.

This is an important concept.

People do not necessarily respond identically to the same medicine at the same dose.

The researchers have developed technology known as TRIPLEcheck, designed to use biomarkers to predict platelet function.

Research reported in September 2026 suggests there may be a substantial variation between individuals in platelet activity and their response to antiplatelet treatment.

This creates two very different potential problems.

Someone who responds particularly strongly to antiplatelet treatment could potentially face an increased risk of bleeding.

At the opposite end of the spectrum, someone whose platelets respond inadequately may remain insufficiently protected against clot formation despite taking the standard medication.

NHS trial involving heart attack patients

According to research reported in September 2026, the technology is now being investigated in a clinical trial involving patients admitted to the Royal Berkshire Hospital following a heart attack.

Around 400 patients are expected to be tested.

The aim is to determine whether analysing individual platelet characteristics can help clinicians make more personalised decisions about antiplatelet treatment.

This is particularly interesting because the research is not simply asking whether aspirin “works”.

The more sophisticated question is:

Does aspirin work sufficiently and safely for this particular patient?

That distinction could become increasingly important in prescribing medicine.

The research remains under investigation and should not be interpreted as meaning that everyone over a certain age should start taking aspirin again. Current NICE guidance continues to state that aspirin should not routinely be offered for primary prevention of cardiovascular disease.

Patients should never start, stop or change prescribed aspirin without appropriate medical advice.

Why can aspirin cause internal bleeding?

The effect that makes aspirin useful also explains one of its principal risks.

If platelets are less able to form a clot, bleeding can be more difficult to stop.

The NHS identifies serious potential aspirin side effects including stomach ulcers and internal stomach bleeding. Aspirin may also be unsuitable for people with certain medical conditions, including previous stomach ulcers, blood-clotting problems and some forms of asthma.

The risks can become more complicated when aspirin is combined with other medicines.

For example, the NHS identifies potential interactions with:

• anticoagulants such as warfarin and rivaroxaban;
• some antidepressants;
• steroid medicines;
• methotrexate;
• blood-pressure medicines; and
• other NSAIDs, including ibuprofen and naproxen.

That is why prescribing decisions should not be considered in isolation. A doctor or pharmacist may need to consider the patient’s age, medical history, other medication and individual bleeding and cardiovascular risks.

Can prescribing aspirin amount to medical negligence?

The fact that somebody experiences bleeding while taking aspirin does not, on its own, establish medical negligence.

Every medicine carries potential risks and side effects.

The relevant legal question is whether the prescribing, dispensing, monitoring or review of the medication fell below the appropriate standard of care and whether that failure caused avoidable injury.

Examples which may warrant investigation could include:

• aspirin being prescribed when there was a clear contraindication;
• an inappropriate dose being prescribed or dispensed;
• aspirin being continued despite significant bleeding symptoms;
• a failure to consider a known history of stomach ulcers or bleeding;
• aspirin being combined inappropriately with another medicine that substantially increased the risk of bleeding;
• a failure to undertake an appropriate medication review;
• a prescription being continued after the clinical reason for it had changed;
• the wrong strength of aspirin being dispensed;
• a patient receiving aspirin intended for somebody else; or
• a failure to provide appropriate information about a material risk where this should reasonably have been discussed.

Our detailed guide to medication error claims explains how prescription, dispensing and monitoring mistakes can give rise to a compensation claim.

Aspirin, warfarin and apixaban are not the same medicines

This distinction is particularly important.

Aspirin is an antiplatelet medicine.

Warfarin, apixaban and rivaroxaban are anticoagulants.

They interfere with clot formation in different ways and have different prescribing and monitoring requirements.

Nevertheless, combining medicines which affect haemostasis can substantially alter bleeding risk. NHS Specialist Pharmacy Service guidance, for example, warns that antiplatelet medicines such as aspirin can increase the bleeding risk associated with direct oral anticoagulants.

We explain these issues separately in our guide to anticoagulant prescription error claims and our article concerning apixaban prescription and dosage errors.

What if aspirin was prescribed for too long?

Long-term treatment is not automatically inappropriate.

For some patients, low-dose aspirin may properly be required for many years and sometimes for life.

The issue is whether there remained an appropriate clinical indication for the medicine and whether important changes in the patient’s health, medication or risk factors should have prompted reconsideration.

For example, a patient may develop gastrointestinal bleeding, start another medicine which increases bleeding risk or experience another significant change in their health.

A prescription should not become appropriate simply because it has been repeatedly issued for years.

Our article on repeat prescription negligence and medication reviews explains why long-term medication may require periodic clinical reconsideration.

What injuries could result from an aspirin medication error?

Depending upon the circumstances, excessive or inappropriate antiplatelet treatment could potentially be associated with:

• gastrointestinal bleeding;
• stomach ulceration;
• significant anaemia following blood loss;
• intracranial bleeding;
• prolonged or excessive bleeding; and
• complications arising from interaction with other medicines.

The opposite problem can also be important.

If aspirin or another antiplatelet medicine is clinically required but is accidentally omitted, stopped or supplied at an inappropriate dose, the patient may potentially lose some of the protection the treatment was intended to provide.

Causation in such cases can be complex and usually requires independent expert medical evidence.

What does the new aspirin research mean for medication negligence claims?

It is too early to suggest that the new test creates a new legal standard of care.

It does not.

The technology is being clinically investigated and the current standard of care must be judged according to the medical knowledge and guidance applicable when the patient was treated.

Nevertheless, the research illustrates an increasingly important principle in modern medicine: the same medicine and dose may not produce the same response in every patient.

If technologies such as TRIPLEcheck are eventually validated and incorporated into routine NHS practice, clinicians may have additional information available when deciding which antiplatelet medicine — and potentially which treatment strategy — is appropriate for an individual patient.

That could eventually make prescribing more personalised rather than relying principally upon population-level risk.

For now, however, existing clinical guidance remains critical.

Can I claim compensation for an aspirin prescription error?

Possibly, if an avoidable medication error caused a significant injury.

A successful clinical negligence claim will generally require evidence that:

1. the doctor, pharmacist, hospital or other healthcare provider owed the patient a duty of care;
2. the treatment fell below the standard reasonably expected;
3. the error probably caused or materially contributed to the injury; and
4. the patient suffered compensatable injury and loss as a result.

An adverse reaction alone is not enough.

For example, a patient could suffer a recognised bleed despite aspirin having been entirely appropriately prescribed. Conversely, there may be grounds for investigation where important risk factors were overlooked, an inappropriate medicine or dose was supplied, or warning symptoms were repeatedly ignored.

Our specialist solicitors can investigate the complete medication history rather than looking at a prescription in isolation.

This can include GP and hospital records, pharmacy records, repeat prescriptions, medication reviews, blood results and evidence concerning other medicines being taken at the relevant time.

Contact Us Now To Claim

Speak to our medication error solicitors

If you believe that you or a family member suffered serious harm because aspirin or another antiplatelet medicine was incorrectly prescribed, dispensed or monitored, Hutcheon Law can investigate what happened.

Medication cases are often more complicated than simply establishing that the wrong tablet was given. It may be necessary to examine why the medicine was prescribed, whether the dosage was appropriate, what other medication was being taken, whether warning signs were acted upon and what would probably have happened with appropriate treatment.

Read our comprehensive guide to medication error compensation claims or contact Hutcheon Law for an initial assessment.

Important: Patients taking prescribed aspirin or other antiplatelet or anticoagulant medication should not stop or alter their treatment because of information contained in this article. Changes to prescribed medication should be discussed with an appropriate healthcare professional.