Half of doctors responding to a BMA survey reported shortages or no supplies of gowns and goggles.
The new guidance said: "The Health and Safety Executive (HSE) has reviewed the options outlined in this document. Where there are acute shortages of PPE, and where it is safe to do so, it approves the sessional and reuse of PPE."
Even though some PPE is designated by manufacturers as being single-use, the guidance said: "The HSE recognises that some compromise is needed to optimise the supply of PPE in times of extreme shortages. It has agreed that the use as outlined in this document is appropriate within health and safety legislation and provides appropriate protection for health and care workers."
It continued: "Further work on validating methods to safely reprocess masks and fluid repellent gowns is underway and future updates will be circulated when available".
Alternatives could also be used, such as wearing aprons instead of gowns to treat COVID-19 patients.
Yesterday the Health and Social Care Secretary for England Matt Hancock admitted he couldn’t guarantee that supplies of gowns wouldn’t run out this weekend.
"Telling staff to use aprons in the place of gowns directly contravenes both Public Health England’s previous guidance and that of the World Health Organisation. This is guidance that’s there to help keep healthcare workers and their patients, out of harms’ way.
“If it’s being proposed that staff reuse equipment, this must be demonstrably driven by science and the best evidence – rather than availability – and it absolutely cannot compromise the protection of healthcare workers.
"Too many healthcare workers have already died. More doctors and their colleagues cannot be expected to put their own lives on the line in a bid to save others, and this new advice means they could be doing just that. It’s not a decision they should have to make."
Dr Samantha Batt-Rawden President of the Doctors’ Association UK said: "This desperate move in downgrading gowns just shows how dire the PPE situation has become on the frontline. It is not acceptable to be using gowns which are not fluid-repellent, or indeed rely just on flimsy plastic aprons and hope for the best."
who have completely let down the same staff we clap for every Thursday."
More than 6000 UK doctors responded to the BMA's snapshot survey.
Among the findings:
Almost 1 in 5 doctors continue to say they do not feel safely protected at work
Around half of doctors working in high-risk areas said there were shortages or no supply at all of long-sleeved disposable gowns and disposable goggles, 56% reported the same issues with full-face visors
In other hospital settings, around half of doctors said that there were shortages or no supply at all of scrubs and eye protection
In both settings, just under a third of doctors said they were sometimes pressured to work without adequate protection
More than a third of GPs said they had no eye protection and a further third reported shortages
More than two-thirds of GPs were not receiving regular and sufficient supplies of eye protection
In a statement, BMA Council Chair Dr Chaand Nagpaul said: "Two months into the COVID-19 crisis in Britain, we shouldn’t still be hearing that doctors feel unprotected when they go to work.
"The Government says that one billion items will soon have been shipped, and while there have been signs of improvement, our research clearly shows that equipment is not reaching all doctors working on the front line."
He continued: "This is a truly sorry state of affairs, and we renew our call for the Government to work with manufacturers to ramp up domestic supply.
"The Health and Social Care Secretary admitted yesterday that there had been 'complications' and that he takes full responsibility. We appeal to him directly to get this problem sorted so that doctors, and their colleagues across the health and social care sector, can treat patients in the face of this deadly virus without putting their own health and lives at risk.
"Too many doctors and healthcare staff have already lost their lives. We cannot afford to risk losing any more."
Director of Policy and Strategy at NHS Providers Miriam Deakin said in a statement: "It’s the absolute priority of trust and national NHS leaders to ensure frontline staff are able to treat and care for patients with confidence in their own safety.
"We know there have been continuing concerns about supplies of PPE equipment, in particular of clinical gowns, and trusts will be following the guidance issued yesterday by Public Health England.
"These recommendations are in line with World Health Organisation guidelines in the event of equipment supplies running low."
In yesterday's Downing Street briefing the Business Secretary Alok Sharma said: "I completely understand that people will be worried if there are shortages, and I'm aware of the supply issues that are being raised.
"There is of course a global supply issue. Everyone is trying to get access to PPE."