The future of a number of hospices is in the balance because of financial losses caused by the coronavirus outbreak, charities say.
Distancing measures have led to charity shops closing and fundraising events like the London Marathon have been cancelled, cutting donations.
Shooting Star Children's Hospices said they were "facing the unthinkable" and could shut without government support.
The government said it was "absolutely committed to keeping hospices open".
Shooting Star has launched an urgent appeal for donations, but chief executive Nigel Harding believes it might not be enough to save them.
The charity has premises in Hampton and Guildford which support about 700 children and young people who have life-limiting conditions in London and Surrey.
It is expecting a shortfall of more than £2m of its annual £11m budget if the current measures remain in place for three months.
Mr Harding said one of the premises had already been mothballed while other services had been cut to save money, but the service could not carry on for a prolonged period without help.
"We do not have big reserves. We've been eating into those for a while so we probably can only continue for four to five months.
"We're desperate for help from the government as are numerous hospices everywhere. It's a national problem," he said
Another of those charities is Royal Trinity Hospice, which supports over 700 adults from its base in Clapham, south London.
The hospice's 32 shops have had to close and without fundraising events they expect a £3m shortfall over the next three months.
"In our 129-year history, we have never faced such a severe challenge," they said.
St Christopher's in Sydenham has also appealed for people's support "now more than ever, to make sure those living with a terminal illness can be certain of our care and support during these uncertain times".
A spokesperson for the Department of Health and Social Care said hospices "play a hugely important role in providing care for thousands at the most difficult time, and last year the prime minister announced a £25 million cash injection to protect the crucial service they provide.
"We are absolutely committed to keeping hospices open during this time and are working closely with the NHS, Together for Short Lives and Hospice UK on an appropriate national response," they said.