A life-saving blood pressure medication taken by millions is in short supply forcing pharmacies to ration prescriptions.

Ramipril is a prescription medication used to treat high blood pressure, heart failure and lower the risks of strokes.

It works by relaxing and widening blood vessels to allow blood to flow more easily.

But the medication, which is taken by about 6 million people in the UK, is in critical supply and health chiefs have put the pills under a “serious shortage protocol” (SSP), which limits patients to just one month's supply of the drug until October 30.

Pharmacists have called on the government to change official guidance so they can offer patients an alternative drug without consulting their GP.

“Millions of patients rely on Ramipril and although there are alternative medicines available, supplies of these must be managed carefully by the government to ensure subsequent demand can be met,” Olivier Picard, chair of the National Pharmacy Association said.

"The government should allow pharmacists to make appropriate substitutions to Ramipril prescriptions to ensure patients do not have to go back to their GP to find an alternative,” he added.

Blood pressure drugs have been in short supply since the start of the year - partly caused by war in the Middle East.

This latest SSP placing a restriction on Ramipril comes after the Department of Health and Social Care issued a restriction on Ramipril 1.25 mg in April, limiting pharmacies to prescribe just 28 tablets at a time.

But because many pharmacies were struggling to meet this the restriction has been extended to October 30.

Pharmacists are not able to prescribe an alternative to Ramipril despite it being in short supply without talking to the patient's doctor first.

If a patient receives fewer pills than what was prescribed, they will not need to pay for their medication.

"Pharmacies are increasingly facing supply problems affecting everyday medicines on which millions rely every day, with some describing shortages as the worst they have ever experienced,” Mr Picard said.

He added: "Whilst the medicine supply chain is complex, the rising problem of shortages across a wide range of medication is extremely worrying for patients and heartbreaking for pharmacists who go to great lengths to ensure they don't turn them away.

"Fragility in the global supply chain is worsened by international instability and this new government must convene an urgent taskforce to fully grip this chronic problem."

The Department of Health and Social Care has been contacted for comment.