One in five people with high blood pressure does not respond to treatment for the condition, however this is often due to an inadequate diagnosis, researchers have said.

High blood pressure, also known as hypertension, is a ‘silent predator' because it rarely carries any signs or symptoms, despite causing damage to blood vessels and the heart. A person can look and feel well even if they have it. The condition is a major cause of heart attack and stroke and two in three Irish people over the age of 45 are affected.

Among those who are treated for the condition, one in five does not respond, however according to German researchers, there is often an underlying reason for this and once that is dealt with, blood pressure control can improve.

They said that one of the main reasons blood pressure treatment may fail to work is due to the medication a patient may be on. Some patients may be taking other drugs alongside their blood pressure medicine, which increases blood pressure as a side-effect.

In such cases, all that is required is an adjustment to the patient's medication.

Diet also plays an important role. For example, patients who are salt-sensitive may increase their blood pressure if they consume salt. Licorice is also known to increase blood pressure so consuming too much can reduce the effectiveness of blood pressure medication.

The researchers insisted that once the underlying reason has been dealt with, blood pressure control is possible. They said that if this approach was taken, half of all cases classified as treatment-resistant hypertension could in fact be treated.

Details of these findings are published in the German medical journal, Deutsches Ärzteblatt International.