At least 70 wards across England and Wales have been shut to new patients due to outbreaks of norovirus.
Claire Conely, a nurse at Conquest Hospital in Hastings, East Sussex, says relatives are often to blame.
"I have had one man come in to visit a relative and vomit in the corridor of the ward.
"I said you have to get out of here.
"I got a complaint against me for asking him to leave."
"People do not understand this bug can seriously hamper the recovery of already ill patients."
Claire works on the elderly care ward which sees outbreaks of norovirus every year but this year the vomiting bug came particularly early - in September.
When a ward is closed it means all unnecessary visitors and staff are banned from the ward and people are not allowed to be discharged to any other institutions such as nursing or rest homes until they have been clear of symptoms for 48 hours.
No new patients can be admitted and patients should not be moved to other parts of the hospital unless absolutely necessary.
"Patients have to wait 48 hours after symptoms so a ward can be shut for up to two weeks."
She added: "Luckily not many members of staff contracted it because of good hygiene.
"The cleaners are very good at getting on top of it."
Those on an elderly care ward are particularly vulnerable as they are frail and can become very dehydrated, she explained.
"It's pretty grim, we have to put a lot of intravenous drips in, whereas younger people could probably manage without."
She urged visitors to stay away from hospital if they have been ill recently with norovirus.
"It generally comes in from the community or incidentally in patients who have contracted it outside but are not yet showing signs.
"Even if you only feel slightly unwell then do not visit people in hospital."