Staff who struggle into work when they are ill risk potentially shortening their lives, researchers believe. Some workers who do not take time off when ill had twice the rate of heart disease, the 10-year study of 10,000 civil servants showed.
The University College London team found that even working with a common cold can be harmful.
The study said it was the stress from working when ill which caused the risk of heart disease.
Professor Sir Michael Marmot, the head of the study, said workers did not realise the damage they were doing. Germs
"So many people force themselves into work when they are not well and have little knowledge of the consequences.
"Far from contributing to their companies or spreading a few germs around the office, they could be hastening their own deaths."
Researchers compared attendance rates with the health records of civil servants and found 30% to 40% of those who did not take time off when ill had double the incidences of coronary disease.
The findings will be broadcast on Wednesday in BBC2's The Money Programme.
Dr Charmaine Griffiths, of the British Heart Foundation, welcomed the report, saying the findings were supported by previous research, which had already shown stress at work could increase the risk of heart disease.
"Different people experience stress in different ways, but people are more likely to feel stressed when they feel they have little control over their work but have a lot of demands placed on them."
Paul Sellers, a policy officer at the Trades Union Congress, said the findings were "pretty serious".
"If this is correct it confirms what we have been saying - you should not go to work when you are ill.
"Some people, particularly in jobs that involve long hours, feel compelled to come to work as promotion is directly linked to how long you spend in the office. Stress
"We need to get the message across this is not productive and, it seems, not healthy."
But the Institute of Directors played down the link between the workplace and heart disease.
A spokesman said: "It seems to us to be a mistake to link stress and heart disease to work.
"It is the illness which is ultimately causing the increased risk.
"You could be putting yourself at risk by doing many things when ill, for example looking after children."
And he denied some workers may feel compelled to go to work when ill.
"Employers realise it is beneficial that if someone is ill they do not come to work." BBC News