Employers' failure to accommodate caring responsibilities of staff is a major cause of absence, research has found.
Lack of workplace flexibility is forcing staff to take time off "sick" to look after children, elderly relatives and other dependants, a study of absence in the NHS reveals.
The findings challenge the notion that tough policies are enough to deal with the absence problem.
Stephen Bevan, associate director of the Institute for Employment studies, which carried out the research, said the problem is particularly affecting women.
The study of 8,000 NHS employees found that 50 per cent of female staff had taken up to five days off in the six months prior to the study to care for dependants.
Half said greater availability of childcare would have reduced their absence.
Last week, Bevan told the Effective Absence Management conference, organised by the IRS, that women have a higher absence rate than men, despite being less likely to malinger.
"The issue is their ability to attend," said Bevan. "When you look at their domestic responsibilities it starts to explain this. We found that the number of children under the age of 16 has a multiplying affect on a woman's absence."
He said that the parental leave regulations will have a positive affect, but allowing flexibility is the best way to deal with the problem.
He added that men are affected too. Three out of 10 men took time off sick to look after dependants over a six-month period.
Yvonne Coventry, head of personnel and training at Frimley Park Hospital NHS Trust, recognised the problem but said it is difficult to deal with because staff do not admit they are taking sick leave to look after dependants.
The hospital has a special leave policy for domestic emergencies, and is reviewing this in light of parental leave, she said.
The NHS has launched a campaign to improve the work/life balance of staff. Hospitals will have to demonstrate what they are doing to improve flexibility.