In research published in the The Lancet, scientists from Utrecht University in the Netherlands reviewed studies from across the world, looking at the relationship between bereavement and physical and mental health.
They said although grief is not an actual disease and most people adjust without professional psychological intervention, bereavement is associated with an increased risk of death, especially in the early weeks and months after loss.
The found that the risk of death increases by up to a fifth following bereavement.
One study found men were 21% more likely to die after the loss of their wife. Widows had a 17% increased risk of death.
Men who lose a wife are also three times more likely to take their own life. Widows, however, do not have an increased suicide risk.
And a Danish study showed fathers and mothers have a raised suicide risk after the death of a child, a risk which is higher the younger the child and is particularly high in the first 30 days post-bereavement.
The Netherlands researchers said that the patterns were consistent, leading to the conclusion that the mortality of bereavement is attributable in large part to a so-called broken heart, the psychological distress due to the loss.
But the researchers stressed that most people cope with grief without professional help.