L-cysteine Probably Isn't the 'Hangover Cure' We're Looking For

From pills to patches, hangover cures routinely pop up on drug store shelves and Instagram feeds alike. A recent small study suggests a new option might actually be effective: L-cysteine supplements. But because the study was so small, experts are skeptical.

"After looking at the limited research, I wouldn't bank on L-cysteine being the winning hangover cure we all hoped for," Tracy Lockwood Beckerman, MS, RD, CDN, a New York City-based registered dietitian, tells Verywell.

That research involved 19 Finnish men who reported less headache and nausea than usual for their hangovers after taking a 1,200 milligram (mg) dose of L-cysteine. Men who took 600 mg of L-cysteine after drinking reported they felt less stressed and anxious than they typically would while hungover.

The study, published in Alcohol and Alcoholism on August 18, required men to drink 1.5 grams of alcohol per kilogram of body weight over a three-hour period. For reference, in the U.S., a standard drink contains roughly 14 grams of alcohol, so a man who weighs 170 pounds would need to consume about eight drinks in this time period.

After drinking, the participants took either placebo tablets, 600 mg of L-cysteine, or 1,200 mg of L-cysteine.

Since many harmful effects of alcohol are produced by its metabolite, acetaldehyde, researchers hypothesized that oral administration of L-cysteine would prevent hangover symptoms by blocking the effects of acetaldehyde in the body.

Brittany Scanniello, RD, a registered dietitian based in Denver, Colorado, explains why this theoretically makes sense. Scanniello tells Verywell that because L-cysteine is sometimes used to support liver function and because alcohol is metabolized in the liver, it's logical to think that L-cysteine supplements may support alcohol metabolism and prevent a hangover.

However, while participants did report reduced hangover symptoms, the study results did not support this hypothesis. Alcohol absorption rates were similar between those who took L-cysteine supplements and those who took placebos. 

How Reliable Is the Data?

This study was randomized, placebo-controlled and double blind—three factors that make for a well-designed study. But there are a few factors that need to be taken into account:

• Results like “less headache” and “less stress” are subjective measures.
• The results are based on a very small sample size and a very specific population of Finnish, non-obese men. 
• The L-cysteine tablets participants consumed are manufactured by Catapult Cat, who funded the study.
• All L-cysteine tablets contained a variety of B-vitamins and vitamin C, which could have also played a role in hangover relief.

"In the present study, the L-cysteine tablets also contained thiamine, riboflavin, niacin, vitamin B6, biotin, folic acid, vitamin B12, and vitamin C," Scanniello says. "It is unclear whether the benefits seen in this study are a result of the L-cysteine or from the multivitamin dose."

Other Ways to Get L-Cysteine

You don't need to take a supplement to consume L-cysteine. While you'd need more than one serving to reap the potential the benefits described in the study, one cup of oatmeal provides 227 mg of L-cysteine. In addition, many protein powders contain amply amounts of the amino acid.

While they're not as hangover-friendly, these foods also provide high levels of L-cysteine:

• 6 oz. pork chop: 595 mg
• 6 oz. skirt steak: 587 mg
• 6 oz. tuna: 546 mg

There is little downside to incorporating L-cysteine into your diet, whether it is via food or supplements. But you should always discuss supplements with your doctor before taking them.

"There is some concern about taking L-cysteine supplements with certain medication, and there is always the question of purity when taking any over-the-counter pill that is not regulated by the Food and Drug Administration,” Scanniello says.

Are There Other Ways to Prevent a Hangover?

Medical literature is full of potential—but unproven—hangover remedies, such as:

• Drinking a pear and green grape juice mixture
• Taking red ginseng during alcohol consumption
• Drinking maple sap before alcohol consumption

Of course, one internet search will lead you to a slew of other hangover remedies. But there's only one surefire way to prevent a hangover: drinking less.

"Regardless of the potential hangover cures you may read about, what we do know is that the less amount of alcohol you consume, the less amount of alcohol-related hangover symptoms your body will endure," Beckerman says.