Asian Flush Ultimate Guide : Everything You Need To Know
By James Petra
Updated on September 05, 2019

If you’re on this article, chances are, you are all too familiar with Asian flush. Some people experience the negative effect of alcohol very severely and it’s due to an enzyme deficiency (more on this later).

So who’s affected by Asian flush?

It affects 40% of those originating from east Asia (China, Japan, Korea, Vietnam) and it occurs after drinking small quantities of alcohol. 

But what exactly causes it? and more importantly, is there a way of stopping it?

In this article, we’ll tell you everything you need to know about Asian flush and what can be done about it.  

RELATED: Best Supplements For Asian Flush Prevention 2019

What causes Asian flush?

It is caused by a deficiency in the ALDH2 (alcohol dehydrogenase) enzyme. This enzyme breaks down acetaldehyde which is one of the main by-products of alcohol break down and responsible for the majority of the symptoms of a hangover. 

So how does acetaldehyde cause damage and hangovers?

Acetaldehyde is a highly unstable and toxic by-product of alcohol metabolism. Your body has a sophisticated system of keeping it in check. The enzyme ALDH2 will break it down into less harmful molecules before clearing it from your body.

However, in people who lack this enzyme, acetaldehyde is left to build-up in your bloodstream which causes significant damage.

Next up, we’ll go over all the symptoms of Asian flush and how they are caused.


Asian flush symptoms

The buildup of acetaldehyde causes very distinctive features in those who suffer from Asian flush which includes:

  1. Facial flushing – rose-red cheeks as well as other body areas
  2. Nausea and vomiting
  3. Headaches
  4. Fast heart rate

But how does acetaldehyde cause these symptoms?

Acetaldehyde related damage is caused by several different mechanisms which we will try to explain next:

Oxidative stress
As mentioned before, acetaldehyde is an unstable molecule which breaks down to form “free-radicals”. Free-radicals cause oxidative damage by reacting with the cells it comes into contact with.

Free-radicals are neutralized by antioxidants which are either produced by your liver or consumed from your diet. In those with Asian flush, the excessive buildup of acetaldehyde and therefore free-radicals leads to this system being pushed over the edge.

Oxidative damage is caused by free-radicals which leads to inflammation. This is particularly a problem in your gastrointestinal tract where the concentrations of acetaldehyde are usually the highest. Therefore leading to nausea and stomach aches.

Immune system activation
Inflammation causes indirect activation of your immune system. This can lead to the release of histamine which can cause flushing and hives.

Is Asian flush an allergy?

An allergy is your immune system responding inappropriately to a non-harmful thing. 

For example, when people with hayfever inhale pollen, the immune system picks this up and sees it as a foreign invader.

Your immune system then mounts an “immune response” to this allergen (pollen) and tries to fight it off. However, pollen is not harmful and the immune system doesn’t need to attack it. 

The typical symptoms of an “allergic reaction” are:

  • hives: red itchy patches that develop on the skin.
  • itchy throat/eyes
  • watery eyes
  • Swelling of the lips/throat/airways – this occurs in severe cases only.

Asian flush syndrome is caused by a buildup of acetaldehyde which has nothing to do with allergies.

That being said, acetaldehyde does cause some symptoms which are similar to an allergy and therefore it’s understandable why the two conditions can be mixed up.

For example, acetaldehyde is known to stimulate the release of histamine and dilate blood vessels which gives you the typical flushed appearance.

Although histamine is known to be the driving force behind allergic reactions, the driving force in Asian flush is a buildup of acetaldehyde and not a massive reaction from your immune system.

Is it genetic?

Genes play a huge role. If both of your parents carry the gene which produces less of the ALDH2 enzyme then this is more likely to be passed onto their children who will have more severe Asian flush symptoms. 

Those who receive only one from their parents will be able to tolerate larger quantities of alcohol and experience symptoms to a less severe extent.

Cancer and Asian flush syndrome: The facts

Studies have shown that individuals with Asian flush syndrome who drink moderate to high quantities of alcohol are at increased risk of developing squamous cell oesophageal cancer.

First of all, what is meant by moderate to high quantities?

There are lots of definitions available online but the most accepted is from the NIAAA (National institute on alcohol abuse and alcoholism):

Moderate: Up to 2 alcoholic drinks per day in men and 1 in women

High:  up to 4 alcoholic drinks per day in men and 3 in women

Therefore the studies suggest that those with Asian flush who drink daily are at increased risk of oesophageal cancer. This link has been attributed to the buildup of acetaldehyde. 

It’s likely due to the fact that acetaldehyde is classed as a carcinogen (cancer-causing molecule). Acetaldehyde is the most abundant carcinogen in tobacco smoke as well.

Other studies have also been carried out to determine a link between Asian flush syndrome and other cancers but have so far been inconclusive in bowel, breast and head and neck cancers.

An important thing to note is that people with Asian flush tend to drink much less anyway because of the negative effects they experience! 

Can you die from Asian flush?

In the short term, Asian flush reactions won’t cause death. If you’ve had a reaction after drinking, eventually you’ll clear all the toxins from your system and your body will repair any damage caused.

In addition, if you’re someone who gets severe reactions from Asian flush, the chances are you probably won’t be drinking much alcohol as the side-effects are too severe.

The problem arises in those who get mild reactions but drink persistently. Over time, the carcinogenic effects of acetaldehyde may cause long term health problems as mentioned above.

Asian flush cure – does it exist?

People with Asian flush syndrome will experience the negative effects of alcohol with only small amounts of alcohol. Because its caused by a deficiency in the enzyme that breaks down acetaldehyde, it’s not possible to stop it from happening in the first place.

The only real way is to not drink at all.

So, unfortunately, there is no way to “cure” Asian flush.

That said, there are some steps that you can take which may help support your liver function.

How to prevent Asian flush naturally

Below we’ve listed some of the most popular ways in reducing the severity of Asian flush reactions.

It’s important to reiterate that you can’t stop Asian flush. The steps below are primarily tips to aid recovery and support liver health.

1) Amino acids – N-Acetyl-cysteine (NAC)

This amino acid is commonly used in hospitals around the world as an antidote to paracetamol overdose. It is believed that NAC is used by the liver to produce more glutathione, known as the master antioxidant which swoops around the body to clear up free radicals.

The breakdown of acetaldehyde will produce huge amounts of free radicals which glutathione will help clear up before too much damage is done.

Some animal studies have shown that giving NAC can significantly reduce the amount of acetaldehyde produced from alcohol consumption. Although there is not much research on its use in Asian flush syndrome specifically, it could have a role to play.

2) Antihistamines

These medications can be purchased over the counter and are commonly used to treat allergic reactions by blocking the effects of histamine.

Histamine is released by certain white blood cells when they sense the body is under attack. As explained earlier, Asian flush syndrome is not an allergic reaction but this white blood cell response can be initiated by a buildup of certain chemicals in our system. Acetaldehyde may again have an important role here.

a study into using antihistamines for Asian flush has shown improvement in their flushing symptoms.

It is important to note that some antihistamines have a sedating effect and can make you sleepy. This is particularly important if you plan to drive or if you work with heavy machinery in which case you need to be cautious. It is advisable to speak to the pharmacist to check before taking antihistamines.

3) Slow down

As the symptoms are as a result of acetaldehyde buildup, giving your liver a chance to process the alcohol you are consuming is a good way of flushing out the toxin from your system and potentially reducing the flushing.

4) Antioxidants

Free radicals play a huge role in making you feel awful after drinking in general. The process of free radical production goes into overload in Asian flush as acetaldehyde builds up the body.

Antioxidants such as Vitamin C and E, as well as alpha-lipoic acid and coenzyme Q10 can help by supporting your body’s natural antioxidant system to clear up as many free radicals as possible.

5) Rehydrate

The oldest trick in the book: drink plenty of fluids

keeping hydrated is key for several reasons. Firstly alcohol is a diuretic meaning that it can stimulate your kidneys to lose more fluid than your actually consuming.

In fact, after drinking a 250ml glass of wine, you will lose an extra 120mls of fluid.

Secondly, the more hydrated you are, the more dilute the toxins in your system will be which will allow your kidneys to flush away the harmful by-products more easily.

A great way to maximize your hydration levels is to invest in a rehydration sachet which you mix with water. These contain essential salts and minerals that help restore what’s lost.

RELATED: Best Supplements For Asian Flush Prevention 2019

zantac for asian flush

Is Pepcid or Zantac good for Asian flush?

Pepcid (Famotidine) and Zantac (Ranitidine) are commonly recommended for Asian flush. But do they actually work?

To understand the answer to this question, we first need to cover how these medicines work.

Pepcid and Zantac are anti-histamines. More specifically, they are histamine receptor number 2 blockers. Commonly known as H2 blockers.

These receptors are mainly found in the cells lining your stomach which are responsible for producing acid to digest food.

Pepcid and Zantac are designed to block this and therefore work to reduce stomach acid.

Unfortunately, this is very different from the receptors responsible for releasing histamine as a result of acetaldehyde build-up.

As a result, these medicines will do not help with reducing Asian flush symptoms.

How long does Asian flush last?

How long the flush reaction lasts will be different from person to person. It’s entirely dependent on how much of the active enzyme ALDH2 enzyme you have and how fast / how much alcohol you’ve been drinking.

After you stop drinking, it could take anywhere from half an hour to several hours.

congeners asian flush

What is the best alcohol for Asian flush?

The flush reaction occurs in response to how much alcohol you are consuming. Therefore, it doesn’t make too much difference which alcohol you choose.

For example, a small bottle of beer may contain a similar amount of alcohol to a shot of vodka. The degree of flush reaction will be the same.

That being said, the exception to this rule is that darker colored drinks can cause a worse reaction. This is because they contain higher levels of congeners.

Independent of acetaldehyde levels, congeners also cause free-radical damage and inflammation and can, therefore, exacerbate Asian flush.

So you may want to avoid darker colored drinks such as whiskey, red wine, and dark beers.

Things to avoid if you have Asian flush

Aside from alcohol itself, there a couple of things you should avoid if you have Asian flush:

Kudzu root

Kudzu extract
Kudzu root extract is a common Asian herbal extract which you’ll find in hangover or liver health supplements. One of the active ingredients in Kudzu blocks ALDH2 which is the enzyme that breaks down acetaldehyde.

This probably won’t make much difference in those with severe Asian flush reaction who completely lack the enzyme. However, the vast majority will have ALDH2 deficiency with some active enzyme left. Taking Kudzu may make symptoms significantly worse in this case.

It’s often assumed that caffeine will “speed up alcohol metabolism” or help flush out toxins faster from your bloodstream. Unfortunately, caffeine does not have any effect on these things.

Caffeine is a stimulant which speeds up your heart rate and is also a diuretic. This means it makes you produce more urine. Therefore caffeine can leave you more dehydrated with a faster heart rate which are things you don’t need if you’re having a flush reaction.

Anything else to consider?

We’ve covered some steps above which go some way to help reduce some of the symptoms of Asian flush. However, it’s important to note that the benefits may only be marginal and the research in this area is still lacking.

If you experience Asian flush badly, it’s probably best to stick to very small quantities of alcohol or even better, avoid completely.

Sticking to the basics by eating a meal before going out and making sure to keep well hydrated throughout your night may help as well.


That brings us to the end of our look into Asian flush including the reason why it happens and what you can do to help reduce the worst reactions.

Ultimately, the Asian flush reaction is caused by a deficiency in the enzyme that breaks down acetaldehyde. Therefore, drinking is always going to be a struggle.

That said, there are plenty of practical steps you can take to reduce the severity of your symptoms. Nowadays, there are supplements designed specifically to support normal liver function and you can find out more about them by following the link below.

Best hangover pills
Check out our pick of the top four Asian flush prevention supplements available to you right now.

James Petra

James is a beer-loving Biochemist and natural health enthusiast from Hull, which is in Yorkshire, England.

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