Hospitals around the UK are being hit by drug shortages after a "tripling demand" sparked by the coronavirus pandemic, according to reports.
Doctors said they are prescribing medicines alternatives to their "drug of choice" as intensive care wards are running low on eight key drugs.
Medics have warned that some "second-choice drugs" might be triggering dangerous side effects such as minor heart attacks, The Sunday Times reports.
The Government has ordered a "parallel export" ban on 196 essential drugs to stop companies buying up drugs meant for UK patients and selling them abroad.
Parallel exporting means buying medicines already placed on the market in the UK so that you can sell them in another country in the European Economic Area (EEA).
Since this can create or worsen medicine shortages, companies that flout the ban risk having their trading licences revoked.
It comes as the government is facing criticism for failing to act early enough to ensure the NHS had all the resources to save the lives of thousands of people.
This month Health Matt Hancock said the government was “confident” that the UK had the medicines it needed.
The government has also been criticised over the lack of adequate personal protective equipment for frontline workers.
Ron Daniels, an intensive care consultant in the West Midlands, said the shortages had become “acute” already.
He said: "We don’t know what we’re going to run out of next week.
"Safety isn’t so much the issue — it’s quality. It may be that we’re subjecting people to longer periods of ventilation than we would normally because the drugs take longer to wear off."
Among the drugs in short supply, there are propofol, a sedative given to those on ventilation; fentanyl and alfentanil, two opioid painkillers used as part of the sedative cocktail in intensive care; and noradrenaline and clonidine, used to treat life-threateningly low blood pressure.
It is also reported that there are "limited supplies" of atracurium, cisatracurium and rocuronium - muscle relaxants used during intubation, when patients are sedated and put on a ventilator to help them breathe.
The doctor added: “We’re using muscle relaxant drugs that I haven’t used for 20 years, such as pancuronium.”
Ravi Mahajan, president of the Royal College of Anaesthetists, said work was being carried out to “preserve” key drugs for those most in need.
He said the high number of COVID-19 patients needing intensive care has increased the demand for drug supplies.
Some doctors have also warned about falling supplies of the painkiller diamorphine - often given to cancer patients - which is being given to coronavirus patients to reduce breathlessness.
Ministers have banned the export of at least three drugs being tested to treat the virus.
They are ritonavir/lopinavir, an HIV treatment, and hydroxychloroquine and chloroquine, both used for preventing malaria.
The Department of Health and Social Care said the Government was “doing everything we can” to ensure that patients “continue to access the medicines they need”.
They added: “We know how distressing shortages can be but we want to assure people that we have well-established processes to manage and mitigate supply problems so that patients continue to receive the high-quality care they expect.”
Stress from coping with the Covid-19 pandemic could lead to a generation of “burnt-out” nurses who will leave the profession when the crisis is over, according to healthcare experts.
Researchers from the universities of Southampton and Surrey have developed new guidance to help support the psychological and mental health needs of nursing staff in a bid to help them deal with the emotional and physical intensity of their work.
The research, published in the Journal of Clinical Nursing, highlights that prior to the Covid-19 outbreak, nurses were already under “considerable stress” because of understaffing, with 44,000 registered nurse vacancies in the UK.
