Should You Take Aspirin Before The Covid Jab? We Ask Experts

HuffPost UK reader Stephen asked: “Should I take aspirin to reduce the risk of blood clots when taking the AstraZeneca vaccination?"
VICTOR HABBICK VISIONS via Getty Images/Science Photo Libra

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HuffPost UK reader Stephen asked: “Should I take aspirin to reduce the risk of blood clots when taking the AstraZeneca vaccination?”

With talk of a potential link between rare blood clots and the AstraZeneca vaccine, some are worried what that might mean for their vaccination – and their health.

In extremely rare incidences, some people have experienced blood clots a couple of weeks after having the first dose of the AstraZeneca vaccine – with a very small number of people dying.

The risk of developing a blood clot is four in one million, while the risk of dying is one in a million. To put that into perspective, travelling 250 miles in a car carries with it a one-in-a-million chance of dying in an accident, according to the BBC.

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So the risk is exceedingly low – but to be on the safe side, the Joint Committee on Vaccination and Immunisation (JCVI) has said that under-30s in the UK can be offered an alternative jab by Pfizer or Moderna where possible.

The blood clot news has startled some people however, with GPs reporting an influx of people calling up concerned about headaches after having the jab.

HuffPost UK has received a few reader questions asking whether taking aspirin before or after the AstraZeneca jab could reduce the blood clot risk. This is likely to because aspirin has been used for decades as a preventative measure for recurring blood clots, as it’s a blood thinning medication – the NHS states it makes the blood less sticky and helps prevent heart attacks and stroke.

The logic goes that it might then help to prevent any blood clots from forming in the body after having the Covid jab. But experts say this isn’t the case.

Professor Beverley Hunt, founder of Thrombosis UK and consultant in thrombosis and haemostasis at Guy’s and St Thomas’ hospital, told a Science Media Centre press briefing “there is no benefit” from taking it.

“We have to remember this is very, very rare,” she said of the possible link between the jab and the rare types of blood clots. Of 20 million vaccine doses administered, a review by the Medicines and Healthcare products Regulatory Agency (MHRA) found 79 cases of these rare blood clots – and 19 deaths.

The blood clots that have been seen have appeared with low levels of blood platelets. It’s thought the vaccine may trigger an immune response which could be responsible for this occurring.

But because it’s very unusual and appears to be linked to the body’s immune response, Prof Hunt says “taking aspirin is not going to be helpful” and “taking an anticoagulant [blood thinner] probably isn’t going to be helpful” either.

“There is no logic at all in taking aspirin after the AstraZeneca vaccine because it will not affect the occurrence of the very rare vaccine-associated thrombosis and thrombocytopenia (VATTS),” she tells HuffPost UK.

“VATTs is driven by an immune response to something in the AstraZeneca vaccine. Furthermore one of the problems with VATTs is a low platelet count, which means there is increased risk of bleeding. Aspirin will make this worse.”

Outside of that, she says, in healthy people, if you take aspirin and you don’t need to take it, the benefits aren’t very good and there’s a risk you can bleed spontaneously. These issues outweigh any benefits in reducing clots.

That said, aspirin does have “enormous benefit” in reducing the risk of further arterial clots in those who have previously had blood clots, she adds. But this won’t apply to those having the AstraZeneca vaccine.

Prof Hunt isn’t alone in her thoughts on aspirin not being very useful in this instance. Dr Kenny Livingstone, a GP and the founder of online doctor platform ZoomDoc, says aspirin isn’t advised as part of pre- or post-vaccination. “There is no current evidence to support taking this medication as part of a preventative strategy to a very, very rare side effect,” he tells HuffPost UK.

If you are at risk of thrombosis or have a past history of blood clots or abnormal platelets, he advises discussing this with your GP before having your vaccine. Those who are already taking aspirin as prescribed by their GP should continue taking it before their vaccine.

An AstraZeneca spokesperson wasn’t able to say whether taking aspirin before or after the vaccine was helpful. However, they did share the following statement: “AstraZeneca continues to support the ongoing investigations by the EMA and MHRA and is working with the regulators to implement changes to the product information.

“The company will continue to monitor all available data and support research to better understand the nature of these events to ensure the safe delivery of the vaccine continues during this global public health crisis.”

Experts are still learning about Covid-19. The information in this story is what was known or available at the time of publication, but guidance could change as scientists discover more about the virus. To keep up to date with health advice and cases in your area, visit and

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