In the loneliest countries by this measure, about 1 in 5 adults has no one to count on, led by South Korea at 19.9%, while the UK's share nearly tripled to 11.4%.

Which country has the most loneliness?

On this measure, South Korea has the highest share of adults with no one to count on, at 19.9%, placing it at the top of the 47 countries in the OECD dataset. Indonesia is close behind at 19.7%, and Peru and Romania each sit at 19.3%. That means roughly one adult in five in each of those countries says they have no relative or friend they could turn to in trouble.

It is worth noting a limit in the data: differences of a point or two between countries may fall within sampling error, so the precise ranking of these four countries is less certain than the broad pattern they share. The data also covers 47 mostly high and middle income countries, so it cannot identify the loneliest country in the world. Japan, which like the UK has appointed a minister for loneliness, stands at 13.0%, up from 10.7% in 2008 to 2010.

What is the least lonely country?

Iceland has the lowest share of adults with no one to count on, at 2.2%, making it the least lonely country by this measure among the 47 tracked. That is well below the median country, which sits at 9.4%.

Türkiye also dropped sharply, from 26.7% to 16.5%. The data cannot show why those shares fell, or whether any specific policy or programme drove the change.

Why are so many countries getting lonelier over time?

The OECD figures show that 28 of the 47 countries saw their share of adults with no one to count on rise since 2008 to 2010, but the data cannot show why. Ireland went from 2.9% to 8.0% and Australia from 4.9% to 10.0%, while the UK nearly tripled from 4.2% to 11.4%. The figures cannot explain whether those rises reflect economic pressures, demographic shifts, housing patterns or something else.

Research published in Nature Communications by a team at Tulane University, tracking 277,489 adults over roughly 14 years, found that loneliness and social isolation were already widespread: a 2023 report estimated that roughly half of U.S. adults experience loneliness, while nearly as many are socially isolated.^{2, 3} Lead author Lu Qi noted that "previous studies found that social isolation and loneliness are related to mortality, especially premature mortality, and this study provides additional evidence."⁴ The OECD series moves in three-year blocks and some changes are not steady over time, so the picture between the two periods compared here may not capture every shift.

What do researchers and health experts say loneliness does to the body?

A study from Tulane University's Celia Scott Weatherhead School of Public and Tropical Medicine, published in Nature Communications, found that loneliness and social isolation were associated with fewer years of life free from major illness, with the sharpest toll on mental health.^{2, 3, 4} Men experiencing both loneliness and social isolation lived approximately 5.8 fewer years free from depression and anxiety, while women lived roughly 3.7 fewer years.^{2, 3, 4} For physical disease, women lost 2.4 disease-free years and men lost 1.7 years.^{3, 4}

Dr. Jay Luthar, a longevity doctor and instructor at Harvard Medical School, explained that "feeling persistently disconnected from others may contribute to prolonged stress responses, changes in stress hormones, and inflammatory processes that could affect cardiovascular and metabolic health over time."¹ Manisha Parulekar, M.D., chief of the division of geriatrics at Hackensack University Medical Center, noted that "loneliness has a greater detrimental effect than social isolation on both physical and mental health."¹ Importantly, the Tulane researchers found that healthier habits reduced the health burden linked to social isolation, but did not significantly reduce the risks associated with loneliness itself, suggesting the two conditions may need different approaches.^{3, 4}

A separate study cited by Theravive, published in Nature Communications, used observational analysis, sibling comparisons and a genetics-based approach called Mendelian randomisation to examine the relationships. Study author Dr. Zoe Reed said the results "highlight the importance of the role loneliness, in particular, may play in mental health and wellbeing" and called for more research to understand how best to target support.⁵