Soften a hangover with 3grams of L-cysteine

If you drink more alcohol than is good for you, a supplement containing a couple of grams of L-cysteine might help reduce the inevitable hangover. We, the ignorant compilers of this free webzine, make this bold statement after reading a 1970s animal study.

Drinking lots of water after overdosing on the legal hard drug known to us as alcohol – and to chemists as ethanol – will not help prevent a hangover. [ Saturday 29 August 2015] You may have seen the news article recently on the web.


The article was based on a Dutch study of a demographic group well known for its disproportionately high alcohol consumption. We will not divulge which loud and at times irritating group was the subject of the study. Stigmatisation is not a habit of ours.

Three grams L-cysteine can soften a hangover
Alcohol itself is not directly responsible for a hangover. Alcohol is a relatively mild toxin. But the enzyme alcohol-dehydrogenase converts alcohol into acetaldehyde [aka acetyl-aldehyde], and that substance is very toxic. The negative consequences of alcohol use – including hangovers – are mainly due to acetaldehyde.

The enzyme, acetaldehyde-dehydrogenase, converts acetaldehyde into harmless acetate or acetic acid. So if you can manage to get acetaldehyde-dehydrogenase to work harder, you may just have worked out a strategy to keep hangovers under control.


In 1974 the American biochemist Herbert Sprince published an animal study that suggested that supplementation with the amino acid L-cysteine [structural formula shown here] is such a strategy. That’s not so strange, as L-cysteine is a building block of glutathione, a tripeptide that is used by acetaldehyde-dehydrogenase.

Sprince gave lab rats a fatal dose of acetaldehyde, thus imitating the effect of a, ahem, really serious hangover. The blue curve in the figure below shows that 90 percent of the lab animals died within one day as a result of the dose they received.

Another group of rats were given not only the fatal dose of acetaldehyde but also L-cysteine. The human equivalent of the dose that Sprince used would be about 3 g for an adult weighing 80 kg. In that group ‘only’ 20 percent of the rats died.


You can buy L-cysteine in lots of webstores. A capsule often contains 500 mg. Going by the results of Sprince’s animal study, then you might be able to soften your hangover by taking 6 capsules just before and during a drinking binge.

Vitamin B1
Sprince did similar experiments with vitamin B1, and discovered that this vitamin on its own also reduced the acetaldehyde mortality, and that it also reinforced the protective effect of L-cysteine. Thats not entirely illogical, as acetaldehyde-dehydrogenase needs vitamin B1.

The doses of vitamin B1 that Sprince used were astronomically high, so we won’t bore you with the results of those experiments. But even so, it might be the case that much lower doses of vitamin B1, which you could easily consume by buying legal supplements, might also reinforce the anti-hangover effect of L-cysteine.