The average worker's income drops by £430 a week if they are only provided with statutory sick pay by their employer, research from LV= has found.
Of those surveyed, 47% would rely on their savings to support them if they were unable to work, while 10% said their savings would run out after less than a week.
Savings to last up to a year were held by 14% while 10% held a form of protection policy.
Losing income as a result of illness affected 38% of workers, while 24% are not paid by their employer when ill for short periods.
The average worker works 10 days a year ill and 54% said they go back to work before they're better, as well as taking five days a year sick leave.
Workers have resorted to hiding illnesses from their bosses, with 34% nationally doing so, rising to 55% in London. These included chronic illnesses and issues such as stress and depression as well as short-term illnesses like cold and flu.
The figures indicated 800,000 workers hid chronic illnesses, while 5m hid stress, depression and other similar ‘hidden issues'.
Reasons for hiding illnesses included bosses looking unfavourably on being ill (38%) and having wages affected (22%).
Richard Rowney, life and pensions managing director at LV=, said: "So often when we talk about sick leave we look at the cost to the wider economy rather than the individual. Whilst no one wants to think about getting ill, none of us are invincible and the reality is that some people will need to be off work for a large chunk of time.
"Although this can have a detrimental impact on an individual's finances and lifestyle, far too few of us have a back- up plan in place that would protect our income if we found ourselves unable to work.
"Having a contingency plan, such as income protection, in place offers peace of mind that if our financial circumstances change due to illness we can focus on recovering rather than worrying about how to pay the bills."
