One in five people over 65 who drink is consuming an “unsafe” level of alcohol, say researchers.
Experts warned that GPs were “less attuned” to drinking problems among elderly people.
Analysis of health records in London found that heavier drinkers tended to be male and relatively affluent.
For older people, the report said, drinking more than the recommended amount carried an additional risk of confusion and falls.
National guidelines advise no more than 14 units of alcohol a week for women and 21 units a week for men.
Researchers used anonymised GP data from 27,991 people aged over 65 living in London.
Of the 9,248 people who reported drinking alcohol, 21% drank more than the safe recommended limits, they report in BMJ Open.
Gender divide
Despite making up just under half of those included in the study, men accounted for 60% of the drinkers and 65% of the unsafe drinkers, the team from King’s College, London, found.
Among the 5% drinking the most alcohol, men were consuming more than 49 units a week – more than a bottle of whisky – and women 23 units a week.
The researchers also found that the problem of unsafe drinking was far more common among the white British and Irish population, than those from Caribbean, African or Asian ethnic groups.
Study author Dr Mark Ashworth, a primary care researcher and GP, said the rates of unsafe drinking in elderly people were higher than those reported for the general population.
“Very few GPs are switched on to the idea that their older patients could be drinking at these levels – we all look out for it in younger patients, but we are less attuned to it in the elderly.
“What is uncertain from this study is whether people are drinking alone, or with friends at home, or down the pub.”
He added that alcohol misuse services were not set up to deal with older patients.
Prof Mark Bellis, alcohol spokesman for the Faculty of Public Health said alcohol products should carry clear health warnings.
“It’s easy for people to slip into a routine of drinking half a bottle of wine a night without knowing it increases their risks of health problems such as cancer and can take years off their life span.
“Having this information is especially important for older drinkers so that they can make informed decisions about their alcohol consumption at a time of life when risks of ill health often increase.”