What Drinks Are High in Congeners? The Science Behind Darker Spirits

November 22, 2025 •

3 min read

Scientific studies show that consuming beverages with high levels of congeners, the byproducts of fermentation, can lead to more severe hangover symptoms compared to low-congener drinks. This makes understanding what drinks are high in congeners a useful strategy for anyone hoping to manage their alcohol's after-effects.

Quick Summary

This article explores congeners, the minor compounds in alcoholic drinks that contribute to flavor, aroma, and color. It details which beverages, particularly darker spirits like whiskey and brandy, contain the highest levels of these substances, and how they contribute to hangover severity. Ethanol is confirmed as the main cause of hangovers, with congeners as an aggravating factor.

Key Points

Darker is Higher: As a general rule, darker alcoholic beverages like bourbon, brandy, and red wine contain significantly higher levels of congeners than clear spirits.
Not the Main Cause: While high-congener drinks can worsen a hangover, the primary cause is the amount of ethanol consumed. Moderation is key.
Flavor vs. Feel: Congeners are crucial for a drink's unique taste and aroma, but they are also the compounds that can intensify next-day symptoms.
Distillation Matters: Highly distilled and filtered spirits like vodka have fewer congeners, while spirits from methods that preserve byproducts, like pot stills, have more.
Research Backed: Studies have compared bourbon and vodka consumption, finding that hangovers are more severe with the high-congener bourbon, even when ethanol intake is the same.
Ethanol's Impact: Despite the role of congeners, ethanol's effects on the body—like dehydration and inflammation—are the main drivers of hangover symptoms.

What Exactly Are Congeners?

Congeners are complex organic compounds, other than ethanol, created during the fermentation and aging of alcoholic beverages. They encompass substances like methanol, acetone, acetaldehyde, esters, and tannins. These compounds, though minor in quantity, impart distinct color, taste, and aroma to drinks, such as the fruity notes in wine or woody flavors in whiskey. Factors like ingredients, yeast, temperature, and aging affect congener type and level.

The Top Contenders: Drinks High in Congeners

A drink's color is a general guide to its congener content; darker drinks usually contain more. This is often due to less distillation and more aging. High-congener drinks include:

Bourbon Whiskey: Frequently cited for high congener levels, potentially 40 times more than vodka. Aging in charred oak is a key factor.
Brandy and Cognac: These fruit-based spirits are rich in congeners, which are vital for their complex taste.
Red Wine: Tannins and other congeners come from fermenting grape skins. White wine has fewer due to less skin contact and filtration.
Dark Rum: Distilled from molasses or sugarcane, dark rum gets its flavor from significant congeners, unlike light rum.
Dark Tequila: Aged tequilas (reposado, añejo) have more congeners than unaged, clear tequila.
Certain Dark Beers: Some dark beers with intricate brewing methods may have higher congener levels than lighter varieties.

High-Congener vs. Low-Congener Drinks

This table illustrates the differences in congener levels in various beverages.


Feature	High-Congener Drinks	Low-Congener Drinks
Appearance	Darker (e.g., amber, red)	Clear or pale (e.g., translucent)
Examples	Bourbon, Brandy, Red Wine, Dark Rum, Tequila	Vodka, Gin, White Wine, Light Rum, Light Beer
Aging	Often aged for longer periods in wooden barrels.	Typically not aged, or aged for shorter durations.
Distillation	May undergo less distillation, preserving more byproducts.	Highly distilled and often filtered to remove impurities.
Flavor Profile	Complex, robust, and distinct flavors from congeners.	Cleaner, more neutral, or less pronounced flavor profiles.
Hangover Severity	Associated with more severe hangover symptoms.	Potentially less severe hangovers, but still dependent on ethanol quantity.

Congeners and the Hangover Effect

Studies link high-congener drinks to worse hangovers. Research comparing bourbon (high congener) and vodka (low congener) showed more severe hangovers with bourbon, even with equal ethanol amounts. The theory is that the body processes congeners alongside ethanol, potentially slowing alcohol metabolite clearance and causing inflammation that leads to headache and nausea. However, the amount of ethanol is the main cause of a hangover; congeners are an aggravating factor, not the primary one.

The Distillation and Aging Processes

Congeners are present based on how a beverage is made. Fermentation creates various compounds besides ethanol. Distillation either removes or concentrates these; continuous stills for clear spirits remove most congeners, while pot stills for whiskies and brandies retain more. Aging in oak barrels also adds and alters chemical compounds, creating new congeners and enhancing flavor.

Conclusion: Navigating Your Choices

Choosing lower-congener drinks like vodka or gin might slightly lessen hangover symptoms for some individuals. However, the most effective way to avoid a hangover is moderation, regardless of the drink. While color can be a simple guide, the total amount of ethanol consumed is the biggest factor. For further information on alcohol's effects, consult the National Institute on Alcohol Abuse and Alcoholism (NIAAA): https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/hangovers. Understanding congener content allows for more informed consumption choices and potentially mitigating some unpleasant after-effects.

Frequently Asked Questions

Bourbon whiskey is frequently cited in studies as having one of the highest congener levels among common alcoholic beverages, with some research indicating it has nearly 40 times more than vodka.

Yes, clear liquors like vodka and gin contain some congeners, but typically in very small amounts. Their highly refined distillation and filtration processes are designed to remove most of these compounds.

Yes, research suggests that the presence of high congener levels can aggravate hangover symptoms. Studies have shown that for the same amount of ethanol consumed, drinks higher in congeners, like bourbon, cause more severe hangovers.

No, congeners are not the only cause. The total amount of ethanol consumed is the main culprit, leading to dehydration, sleep disruption, and other negative effects. Congeners are a contributing factor that can intensify symptoms.

Individual tolerance and genetics play a significant role in how a person reacts to both ethanol and congeners. Factors like sleep quality, hydration, and other habits also influence hangover severity, making the experience highly personal.

Congeners are naturally produced during the fermentation of sugars by yeast. Additional congeners can be introduced or modified during the aging process, such as when a spirit is stored in oak barrels.

Not necessarily. Congener levels are more related to the type of beverage and its production method than its price. For example, an expensive dark spirit can have higher congeners than a cheap clear one.