Soaring numbers of over-50s in England will suffer from loneliness in the coming years as a result of widowhood, ill-health and money problems, according to a new analysis.

More than two million people of that age will be lonely by 2025-26, a 49% increase on the 1.36m who were socially isolated in 2015-16, according to projections by Age UK.

While the proportion of the population who say they “often” feel lonely will not change from one in 12, the number of those affected will rise as a result of the increase in numbers of people over 50.

The findings come as the government finalises its strategy to combat loneliness, which charities, councils and health experts say has increased in recent years as a result of lengthening lifespans, cuts to social care services and families becoming more spread geographically.

Age UK warns that the problem is a looming “major public health concern, because if loneliness is not addressed it can become chronic, seriously affecting people’s health and wellbeing”. Lonely people are more likely to report mental and physical ill-health.

“Loneliness can blight your life just as badly if you are 18, 38 or 78. But our analysis found that different life events tend to trigger the problem depending on your age,” said Caroline Abrahams, Age UK’s charity director.

“It makes sense to target help at people going through the kinds of challenging experiences that put people at risk, whether you are in your youth and leaving college; in mid life and going through a divorce; or in later life, having recently been bereaved.”

Its analysis of findings in the English Longitudinal Study of Ageing identified over-50s as a group particularly at risk of loneliness and the likely triggers for that. For example, widowers are more than five times as likely to report feeling “often lonely” as peers who are in a relationship. Having someone to open up to about their lives is often a predictor of loneliness, the charity found.

Similarly, those over 50 are four times more likely to feel “often lonely” if they are in poor health compared with those who continue to have good or excellent health. Over-50s struggling with financial problems are twice as likely to feel lonely as those who are not.

“Loneliness is a far from trivial issue. It can have a devastating effect on people’s physical and mental health, as well as placing an increasing burden on health and social care,” said councillor Ian Hudspeth, the chairman of the wellbeing board of the Local Government Association, which represents councils.

“For too many people, loneliness is their reality all year round. They are often less able to look after themselves, which can make existing health conditions worse and are more likely to become reliant on public services sooner.”

He lamented the loss of “community connector” services, which help mainly older people who are isolated participate in social activities in their area. The service has been reduced as a result of councils having their budgets cut by central government in recent years.

A spokesperson for the Department for Digital, Culture, Media and Sport, which is leading the government’s efforts to tackle loneliness, said: “Loneliness is an issue that can affect anyone and we are committed to tackling it. We have set up an £11m fund to better connect people across the country and our soon-to-be-launched loneliness strategy – the first of its kind in the world – will be a step to overcoming social isolation within society.”