Do Tannins Cause Headaches? What Red Wine Actually Does to Your Body

For decades, tannins have taken the blame for red wine headaches. Search "do tannins cause headaches" and almost every result points the finger at these bitter, mouth-drying polyphenols as the reason a single glass of Cabernet can leave someone reaching for ibuprofen. It sounds logical — red wine is loaded with tannins, white wine isn't, and red wine causes far more headaches.

But a 2023 study from UC Davis upended that story. Researchers at the university identified a different compound — quercetin glucuronide, a metabolite of the flavonoid quercetin — as a potent inhibitor of ALDH2, the enzyme responsible for clearing acetaldehyde from the body. When ALDH2 is blocked, acetaldehyde builds up fast, dilating blood vessels, triggering inflammation, and producing the throbbing pain that defines the tannins headache reputation. The problem was never tannins alone. It was a flavonoid hiding behind them.

That doesn't mean tannins are innocent. They play a supporting role through serotonin release and histamine liberation. But the headline finding — that quercetin directly sabotages acetaldehyde clearance — changes what actually works for prevention. And for anyone who gets a headache after just a small amount of alcohol, red wine is the single most reported trigger.

Here's how each compound contributes — and what the science says about the one that matters most.

What are tannins and why is red wine so full of them?

Tannins are a class of polyphenolic compounds, large, complex molecules that bind to proteins and other organic compounds. In wine, they come from two sources: the grape itself (skins, seeds, and stems) and the oak barrels used for aging.

The tannins you taste in red wine are primarily condensed tannins (also called proanthocyanidins), extracted from grape skins and seeds during fermentation. When red wine is made, the crushed grapes, skins and all, sit in the juice for days or weeks in a process called maceration. This extended skin contact is what gives red wine its colour, its body, and its tannins. White wine has the skins removed almost immediately, which is why it contains virtually no tannins at all.

Oak barrels contribute a different type: ellagitannins, wood-derived tannins that add structure and subtle flavour during ageing. A Cabernet Sauvignon aged 18 months in new French oak has substantially more tannin than the same wine aged in stainless steel.

Tannin levels vary dramatically by grape variety. High-tannin grapes include Cabernet Sauvignon, Nebbiolo, Tannat, and Petit Verdot, wines that feel dry and grippy on the palate. Low-tannin varieties like Pinot Noir, Grenache, and Gamay are lighter, smoother, and, for headache-prone drinkers, often a better bet.

So do tannins themselves cause headaches? There's some evidence that tannins can trigger serotonin release from platelets, which may provoke headaches in people prone to migraines. They can also act as histamine liberators, prompting your body to release more histamine than it otherwise would. But if tannins alone were the problem, you'd expect tea, which is loaded with tannins, to cause the same headaches. And for most people, it doesn't. Something else in red wine is doing the heavy lifting.

The quercetin discovery: why red wine uniquely blocks acetaldehyde clearance

In 2023, researchers at UC Davis published a study in Nature Scientific Reports that identified the most compelling mechanism yet for the red wine headache. Devi et al. (2023) showed that quercetin glucuronide, the form that the flavonoid quercetin takes once it's metabolized in your body, is a potent inhibitor of ALDH2, the enzyme responsible for breaking down acetaldehyde.

Here's why that matters. Every time you drink alcohol, your liver converts ethanol into acetaldehyde, a compound that's 10 to 30 times more toxic than alcohol itself. Normally, ALDH2 clears it quickly. But when quercetin glucuronide blocks ALDH2, acetaldehyde accumulates. And acetaldehyde is directly responsible for headaches: it dilates blood vessels, triggers inflammatory pathways, and stimulates pain-sensitive nerves.

Red wine is loaded with quercetin because the compound concentrates in grape skins. Since red wine is fermented with skin contact and white wine isn't, red wine contains roughly ten times more quercetin. Sun-exposed grapes have even higher levels, which is why that big, sunny Napa Cabernet might hit harder than a cooler-climate Pinot Noir.

The connection to ALDH2 deficiency makes this even more relevant. Around 540 million people worldwide, predominantly of East Asian descent, carry the ALDH2*2 genetic variant, which already reduces their ALDH2 enzyme activity by up to 95%. For these individuals, the quercetin in red wine compounds an existing problem. But even people with fully functional ALDH2 can experience temporary enzyme inhibition from quercetin, which explains why red wine headaches aren't limited to any one population.

The distinction matters: tannins may contribute to wine headaches through serotonin and histamine pathways, but quercetin appears to trigger the acetaldehyde buildup that makes red wine headaches uniquely fast, uniquely painful, and uniquely tied to red wine over white.

For a full explanation of how your body processes acetaldehyde, we've put together an in-depth guide.

If you have Asian flush, or notice flushing when you drink red wine specifically, the quercetin-ALDH2 connection is directly relevant to you. Sunset is formulated to support ALDH2 enzyme activity. Learn more ->

Histamines in red wine: the itch-and-headache connection

Histamine is the second major headache mechanism in red wine, and it works through a completely different pathway than quercetin.

Red wine contains among the highest histamine levels of any alcoholic drink, typically 0.5 to 27 mg/L, compared to less than 1 mg/L in most white wines. This histamine is produced during fermentation, particularly during malolactic fermentation, the secondary process that softens a wine's acidity. According to a study of histamine in wine, histamine levels can vary enormously depending on grape variety, fermentation conditions, and bacterial strains involved.

When histamine enters your bloodstream, it binds to H1 receptors in blood vessel walls, causing vasodilation, a widening of the blood vessels, including those in your brain. This vasodilation stretches pain-sensitive nerve fibres surrounding the blood vessels, producing that characteristic throbbing headache.

Alcohol makes the problem worse in two ways. First, ethanol itself triggers mast cells to release additional histamine from your body's own stores. Second, alcohol inhibits diamine oxidase (DAO), the enzyme responsible for breaking down dietary histamine in the gut. So you're absorbing more histamine from the wine while simultaneously losing your ability to neutralise it.

This is why some people find that an over-the-counter antihistamine like cetirizine (Zyrtec) or loratadine (Claritin) helps with wine headaches. If histamine is your primary trigger, blocking H1 receptors can make a noticeable difference. But antihistamines won't touch the acetaldehyde pathway, so if quercetin-mediated ALDH2 inhibition is also involved, you'll still get a headache.

Sulphites: the most common scapegoat (but not the main culprit)

Ask anyone what causes wine headaches and there's a good chance they'll say sulphites. It's one of the most persistent myths in wine culture, and the evidence doesn't support it.

Sulphites (sulphur dioxide, SO2) are added to wine as a preservative to prevent oxidation and microbial spoilage. They also occur naturally during fermentation. Here's the thing most people get wrong: white wine typically contains more added sulphites than red wine. Red wine's natural tannins act as antioxidants, so it needs less SO2 to stay stable. If sulphites were the primary headache trigger, white wine would cause more headaches than red, and for the vast majority of people, the opposite is true.

True sulphite sensitivity is relatively rare, affecting an estimated 1% of the general population and roughly 5% of people with asthma. Its hallmark symptoms are respiratory, including wheezing, chest tightness, and bronchospasm, not headache. A comprehensive review of sulphite sensitivity published in the journal Foods confirms that the link between sulphites and headaches remains weak at best.

This doesn't mean sulphites are completely harmless. Some people do report headache-like symptoms, and individual sensitivity varies. But if you're specifically trying to figure out why red wine gives you a headache and white wine doesn't, sulphites are almost certainly not your answer.

For a broader look at sulphites in wine and other drinks, including the actual levels in different beverages, we've covered that separately. And if sparkling wine also gives you trouble, why champagne causes headaches involves its own set of factors.

Why some people are more sensitive to red wine headaches

If you've ever watched someone drink the same bottle of red wine without any issues while you're reaching for ibuprofen, you already know: susceptibility is wildly individual. Three factors explain most of the variation.

ALDH2 genotype is the single biggest predictor. People who carry the ALDH2 deficiency variant already have compromised acetaldehyde clearance. When quercetin glucuronide further inhibits whatever ALDH2 function they have left, the effect is compounded. This is why red wine is often the worst drink for people with Asian flush: it's hitting an enzyme system that's already running at a fraction of its capacity.

DAO enzyme levels determine how well you handle the histamine load. Genetic variants in the DAO gene can reduce enzyme production, leading to histamine intolerance that affects an estimated 1–3% of the population. If this is you, red wine's high histamine content hits harder than it does for most people.

Migraine predisposition lowers the threshold for all of these triggers. The trigeminovascular system, the network of nerves and blood vessels that drives migraine pain, can be activated by acetaldehyde, histamine, and serotonin fluctuations from tannins. If your baseline migraine threshold is already low from genetics, stress, or poor sleep, one glass of Cabernet may be enough to push you over the edge.

The worst-case scenario is having all three: reduced ALDH2, low DAO, and migraine susceptibility. If that combination sounds like you, red wine is probably the hardest drink your body can face.

Practical advice: how to enjoy red wine with fewer headaches

You don't necessarily have to give up red wine entirely. Here's what the evidence supports.

Choose lower-tannin varieties. Pinot Noir, Grenache, and Gamay are lighter on tannins and generally contain less quercetin than powerhouses like Cabernet Sauvignon or Nebbiolo. Cooler-climate wines tend to have lower quercetin levels, since quercetin production increases with UV exposure.

Drink younger wines. As wines age, tannins undergo polymerisation, binding together into larger, softer molecules. But the trade-off isn't straightforward: aged wines may have concentrated quercetin. Younger, lighter reds are generally a safer starting point.

Eat before you drink. Food in your stomach slows alcohol absorption, giving your ALDH2 enzyme more time to process acetaldehyde at a manageable rate. Protein and fat are more effective than carbs for this purpose.

Stay hydrated. A glass of water between each glass of wine won't stop a quercetin-mediated headache on its own, but dehydration amplifies every headache mechanism. It's the simplest thing you can do that still makes a difference.

Consider antihistamines (with caveats). If your headaches are driven by histamine, cetirizine or loratadine before drinking can help. H2 blockers like famotidine (Pepcid) target a different histamine receptor. Neither addresses the acetaldehyde pathway, and they come with their own side effects, so treat them as a partial fix, not a complete one.

Support acetaldehyde clearance. For people whose headaches are driven by the quercetin-ALDH2 pathway, especially those with ALDH2 deficiency or alcohol flush reaction, supporting the enzyme that clears acetaldehyde is the most targeted approach. Ingredients like dihydromyricetin (DHM) and NAC have shown promise in supporting this pathway.

For people who notice that red wine hits them harder than white wine or clear spirits, ALDH2 enzyme support before drinking can make a real difference. Shop Sunset Alcohol Flush Support ->

Read more: How your body processes acetaldehyde -> | The ultimate Asian flush guide ->