Systemic corticosteroids such as dexamethasone should be used to treat patients with critical or severe Covid-19 but not patients with ‘non-severe’ illness, England’s chief pharmaceutical officer Keith Ridge has said.

This will apply “primarily” to Covid-19 patients who are hospitalised and receiving supplemental oxygen, explained Mr Ridge and NHS England & Improvement national medical director Stephen Powis in a November 13 letter to medical directors, regional chief pharmacists and hospital chief pharmacists.

“However, there may be occasions when UK patients with Covid-19 meet the WHO criteria of severe or critical, but are not hospitalised.”

Dexamethasone should only be used in adults as its use in children is still being studied, the letter says, adding that pregnant or breastfeeding women should receive oral prednisolone or intravenous hydrocortisone instead of dexamethasone.

Hospital pharmacists “should ensure prescribing guidance is followed,” Mr Ridge and professor Powis said.

Low-cost and widely produced, dexamethasone became the first drug clinically proven to reduce deaths in patients hospitalised with Covid-19 in June.

In Oxford University’s RECOVERY trial, administering 6mg once per day for 10 days brought down deaths by one third in patients who needed ventilation and by a fifth in patients only receiving oxygen, but was not found to improve the prognosis for patients who did not need any respiratory intervention.