Two vodkas is enough to increase the risk of stumbling and falling for someone aged over 60, research has shown.
The findings confirmed that even small amounts of alcohol at the legal limit for driving can seriously impair reaction times while walking.
They may help explain the numerous accounts of older people taking a tumble after having a drink, say Dutch scientists.
Thirteen volunteers with an average age of 62 took part in tests which involved walking on a treadmill and having to step over an unexpected obstacle.
A computer triggered the release of a wooden block so that it dropped in front of the volunteer's left foot.
Participants struggled to avoid the obstacle after just two single vodka and oranges.
Judith Hegeman, of the Inst-itute for Fundamental and Clinical Human Movement Sciences, said: "We found that alcohol levels considered to be safe for driving seriously hamper the ability to successfully avoid sudden obstacles in the travel path."
The drinks were mixed with the aim of roughly meeting the common legal driving limits of 0.05pc for most European countries. The authors said that after two drinks, the "obstacle avoidance reactions are inadequate, late, and too small".