Does beer go bad?

In this brief guide, we will answer the query, “Does beer go bad?” and will discuss the factors that affect beer.

Does beer go bad?

Yes, beer does go bad.  Like all foods, beer, too, ultimately succumbs to deterioration, just like the plants from which it is derived. While brewers strive to make beer survive as long as possible, microbes and chemical reactions always find a way to spoil it. Light exposure, oxygen exposure, and microbial exposure are three of the most common ways aged beer loses its taste. The shelf-life-limiting factor of beer products is the deterioration of its attractive aroma together with bitterness (1).

Factors that affect beer shelf life

The flavor instability upon storage is still one of the most important quality problems of beer, thus limiting the shelf life of the beverage. A large number of constituents form the complex beer matrix and chemical reactions inevitably produce alterations both in the composition of beer, and in its taste and flavor. Thus, beer quality changes constantly during storage (1).

A beer’s sell-by date is typically only an estimate since there are so many variables that affect how long a beer may be stored. Some things to keep in mind when it comes to your beer trip from the brewhouse to your cup.


The beer’s ability to age depends in part on the distance it travels throughout its distribution cycle. Longer distances indicate that your beer is more likely to have been disturbed, exposed to heat or sun, or any other kind of degradation by the time it reaches you. Fresh beer is what you can expect from a local brew. In the transportation and storage chain, beers should be kept at refrigerated temperature (under 7 °C) to inhibit the staling reactions. Additionally, subjecting the beer to vibrations or shocks should be avoided since those can enhance the beer oxidation rate (2).


One of the main challenges of the brewing industry is to preserve the freshness and the flavor of their products during transport and storage until the product reaches the final consumer. Temperature, storage time and vibrations are the most common external factors impacting bottled beer flavor stability post-packaging (2). 

Where did you purchase it, how quickly is it selling? Your favorite imperial stout hasn’t been sitting around for long if it’s hard to maintain in stock due to high demand. Items that have gathered dust for years might be considerably older.


Keeping beer fresher for extended periods is easier with cans because of their ability to block out sunlight and seal out oxygen and other possible pathogens. The brown glass bottles, which function as sunglasses to block out UV rays and protect your beer from being skunky, are an alternative to cans if you don’t like the look of them; green bottles are equally useful. Ultraviolet radiation has the easiest time penetrating clear bottles since they are transparent.


Carbonyl compounds, typically associated with staling off-flavors or indicators of flavor deterioration, are the main characteristics evaluated to assess the impact of beer exposure to temperature. Furfural and Strecker aldehydes were analyzed by studies in pale lager beer stored in the dark at 30°C (86°F) up to 120 days, which reported that furfural concentration increased between 10 up to 30 times and aldehydes from Strecker degradation (2-methylpropanal, 2-methylbutanal, 3-methylbutanal, methional, benzaldehyde and phenylacetaldehyde) and lipid oxidation (hexanal and trans-2-nonenal) increased by 2.5 times on average (2). 

The iso-a-acids are compounds derived from hops, which give the beer its bitterness. The degradation of the iso-a-acids is accelerated by increased temperature and exposure to light (1).

It’s important to know how cold the beer is being kept before you purchase it. Refrigeration and keeping it out of direct sunlight are essential if you want your beer to last as long as possible while also improving the flavor. Another thing to check for is if bottles and cans are kept upright, which reduces oxidation better than those placed on their sides and allows them to last longer.

Is it possible to become ill from drinking old beer?

Biological stability is currently a threat controlled by most of the breweries. Good hygiene practices, efficient filtration and pasteurization routines minimize the risk of microorganism’s (bacteria, yeast or fungi) contamination and are widely implemented in the beer industry. Additionally, the intrinsic beer properties, namely, the low pH, alcohol concentration, antiseptic action of hop acids, anaerobic environment and carbonation, do not favor microbial growth (2).

It’s not a good idea to drink beer that’s over its expiry date, but if you do, just know that you won’t get sick or die from ingesting “rotten beer.” The worst-case scenario is that you’ll have a little stomach pain and a vague sense of dismay and disgust. To be on the safe side, avoid drinking expired or poor beer if at all possible. You should be able to drink your beer even if you smell a faint odor of skunk in it.

Before it goes bad, how long can you keep beer?

Beers with low alcohol by volume (ABV) placed on a shelf, unopened will become flat after approximately 6 months. Lambics and stouts, both of which have a higher alcohol content, are meant to be aged or cellared, thus keeping them for a few years improves their flavor. Make sure they’re properly kept, and you’ll be OK. This article has further information on how to preserve and cellar beer correctly.

The shelf life of beer depends also on its packaging. Studies evaluated various packaging types (glass bottle, PET bottle, aluminum can and stainless-steel keg) on some physicochemical and sensory properties of Czech-type lager beer after 12-month storage. Results showed that the carbon dioxide content of beer stored in PET bottles rapidly decreased (from 0.5% to 0.36% w/w) while beer stored in the other types of packages remained almost constant (2).

When beer is opened, its shelf life is reduced. Putting beer in the fridge for more than a few hours causes it to get flat. In our opinion, the best course of action is to avoid making beginner mistakes while drinking a beer. Finish it, please (responsibly, of course). Don’t put it off till the future. In the same way that a flat Coke has lost all of its carbonation, so does a flat beer. Carbonation gives it a refreshing flavor and a salivating mouthfeel.


Skunked Or Skunky Beer: What Is It?

“Skunking” or “light trucking” a beer occurs when it is exposed to light for a long time. Drinking a skunked beer isn’t harmful, but the smell and flavor are revolting. Don’t skunk your beer, since you were designed to enjoy it! You can’t get this beer back to normal even if you soak it in tomato juice.

The old beer off-flavor formation and the loss of pleasant beer bitterness and fresh notes is mainly related to iso-α-acids degradation and loss in ester compounds, respectively, and the staling flavors are due to increased carbonyl compound concentrations. The rate in which these phenomena are directly related to storage in high temperatures and the presence of light (2).

You can keep your beer fresh by keeping it in a cool, dark spot away from sunshine or direct light. It’s impossible to get to your beer if it’s in a keg or a can. Bottles with their tops on are best stored this way. It is not necessary to keep a capped beer on its side, as is the case with wine that has a cork.

Expired unpasteurized beer is safe to drink

Simply put, the answer is “No!” The only exception to this rule is unpasteurized beer. Expired, unpasteurized beer might make you ill, so stay away from it. Some brewers don’t pasteurize their beers because they believe it enhances the flavor of the beer, which they believe to be the case. It’s best to drink unpasteurized beers right out of the bottle. Unpasteurized beer has a shorter shelf life and may be contaminated with lactic acid bacteria (3).

Other FAQs about Beer  that you may be interested in.

Is beer vegetarian?

Can you live off Beer?

Can you survive on beer without water?


In this brief guide, we answered the query, “Does beer go bad?” and discussed the factors that affect beer.


  1. Aguiar, D., Pereira, A.C. & Marques, J.C. The Influence of Transport and Storage Conditions on Beer Stability—a Systematic Review. Food Bioprocess Technol, 2022. 
  2. Caballero, Isabel, Carlos A. Blanco, and María Porras. Iso-α-acids, bitterness and loss of beer quality during storage. Trend Food Sci Technol, 2012, 26, 21-30.
  3. Silvetti, T., et al. Effects of lysozyme on the microbiological stability and organoleptic properties of unpasteurized beer. J Inst Brew, 2010, 116, 33-40.