Patients who take blood thinning drugs for heart problems have been reassured that the Covid-19 vaccine should not cause adverse effects if their condition is stable.

Anti-coagulant treatments including Warfarin are prescribed to patients at increased risk of strokes or those who have a metal heart valve or those with conditions including Atrial Fibrillation.

Like most vaccines, the coronavirus vaccine is injected into the muscle of the upper arm and may bleedmore than injections that are given under the skin but less than those that are administered into a vein.

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According to British Heart Foundation Scotland, for patients on drug thinning medication the bleeding may take a little longer to stop resulting in bruising on the upper arm. Patients taking anti-platelet medication may also experience more bleeding.

Dr Thomas Christie Williams, Clinical Lecturer at Edinburgh University, said: "People take warfarin to thin their blood if they have a metal heart valve (prone to clotting) or have had strokes, or are at increased risk of strokes (more likely to have the clots that can cause these). 

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"If you are on warfarin and aren't sure about your INR (a measure of how quickly your blood clots) you might bleed very easily and end up with a large bruise from the blood.

"Public Health England say that if your INR is stable it is fine to have vaccine."

Pregnant women have been advised to delay the vaccine as well as those with severe allergies after two NHS workers developed adverse symptoms.