Prickly pear cactus extract is available at some health-supplement stores. It has been used in sunburn ointments and as a diet supplement, supposedly to reduce blood sugar levels.
The study found that when taken hours before drinking, the extract can alleviate symptoms such as dry mouth and that nauseated, can't-stand-the-sight-of-food feeling.
It does not appear to ease other symptoms, such as headaches and dizziness.
But unlike raw egg mixtures, cold pizza, greasy breakfasts and other folk remedies, the extract helps prevent the symptoms instead of trying to relieve them after the misery has begun.
The study appears in Monday's Archives of Internal Medicine and was led by Dr. Jeff Wiese at the Tulane Health Sciences Center in New Orleans, a city that knows hangovers.
The authors received financial support from the federal government and from a nutritional supplement company that markets prickly pear extract.
Wiese and his colleagues recruited 64 healthy young adults. Half of them took the extract, half took a placebo. Five hours later, they began to drink. Volunteers drank whatever kind of liquor they preferred, and downed over four hours the equivalent of about five to seven drinks for a 150-pound person.
The study participants were then driven home. The next day, they rated their hangover symptoms. Two weeks later, the experiment was repeated, with the placebo group and the extract group changing places.
Each time, the participants who had taken the extract rated their nausea, dry mouth and aversion to food to be significantly less severe. The risk of severe hangover was cut in half with the extract, the authors reported.
Wiese said the study also seemed to confirm the folk wisdom that brown liquor causes worse hangovers than clear liquor. Bourbon and scotch — liquor with high levels of impurities called congeners — caused worse hangovers than relatively congener-free liquor such as vodka and gin.
Wiese said the results lend support to his theory that hangovers, which the doctors call veisalgia, are caused at least in part by inflammation, which the prickly pear extract has been shown to reduce.
Dr. James Zacny of the University of Chicago Medical School said the researchers did not measure whether the extract eases that foggy-headed morning-after feeling. Without knowing that, it is too soon to say whether the extract is beneficial, Zacny said.
Zacny said hangovers might be a kind of protective device to keep us from doing something we shouldn't do — such as driving or operating a band saw.
Wiese said hangovers surely cost the United States billions of dollars in lost productivity. He cited "Kreitman's Paradox," named for researcher Norman Kreitman: The people hung over most frequently are the light to moderate drinkers. And those people tend to be gainfully employed.