The time of day a patient takes medication for their high blood pressure makes no difference to how well the medication works, according to a large observational study led by an international team of researchers from Spain and the UK.

It is the biggest study to date addressing the question of timing of blood pressure medication.

The study findings, published in the Journal of Hypertension, are from more than 28,000 people who were observed over 10 years as part of the Spanish Ambulatory Blood Pressure Monitoring Registry.

They show that timing of medication does not influence risk of death from cardiovascular causes, or any other causes – reinforcing the results of a UK trial called TIME (Treatment in Morning vs Evening) published in The Lancet last year.

The results of both studies do not support a theory that has been proposed that taking blood pressure medication at bed-time may provide greater protection against heart attack, stroke and other cardiovascular diseases.

More than one billion people have high blood pressure worldwide, and high blood pressure is the leading global cause of premature death.

The authors of the latest paper said patients should be reassured that they can take their medication when it is most convenient for them.

First author of the paper and ISH member Alex de la Sierra said: “Our study had more participants than any other study that has been done to look at the timing of blood pressure medication and its impact – and we followed participants for twice as long as usual in a trial.

“We found no evidence of a link between the timing of medication and cardiovascular outcomes, and the message to patients is clear: that the time of day they take their medication is not important.”

President of the International Society of Hypertension and an author of the paper Bryan Williams said: “There has been huge controversy about whether the timing of when you take your meds for high blood pressure can influence your risk of heart disease and stroke: specifically, that bedtime dosing might be better at reducing future risk of heart disease and stroke.

“This important new study, the largest study of its kind, unequivocally suggests that timing of treatment doesn’t matter. This supports the conclusion of a pivotal British trial published in The Lancet last year.