What to do if I accidentally drank spoiled milk? (3 recommendations)

In this brief guide, we will answer the question “What to do if I accidentally drank spoiled milk?”. Moreover, we will also discuss how milk gets spoiled, how you can tell if milk is spoiled and how to properly store it.

What to do if I accidentally drank spoiled milk?

If you have ingested spoiled milk, taking immediate action is crucial because you may have a foodborne illness. Begin by swishing water in your mouth and spitting it out several times to remove the unpleasant taste (1,2).

Drink plenty of clean, fresh water to dilute any remaining residue, help flush out any toxins to maintain your fluid balance and help combat dehydration caused by potential gastrointestinal symptoms. Hydration is essential to replace lost fluids and prevent dehydration (1,2).

If you have consumed only a small amount of spoiled milk, the risk of contamination is relatively low. However, if you have ingested a significant quantity and experience adverse symptoms, it’s advisable to seek consultation with a healthcare professional for a proper diagnosis and any necessary treatment (1,2). 

What happens when you consume spoiled milk?

Consuming spoiled milk can cause foodborne illness or food poisoning since spoiled milk can contain harmful bacteria like pathogenic strains of Escherichia coli, Salmonella, or Listeria (1,2).

Depending on how much spoiled milk you sipped, your symptoms may include (1,2):

  • vomiting
  • nausea
  • stomach cramps
  • diarrhea 

In severe cases, you may feel fever and dehydration. All these symptoms occur because the body reacts to the presence of harmful microorganisms trying to expel them, often resulting in gastrointestinal distress (3). 

How does milk get spoiled?

Milk spoils primarily due to the growth of microorganisms, particularly bacteria, which feed on the nutrients in milk. Initially, fresh milk contains a few bacteria, but when it’s exposed to air and slightly elevated temperatures, these bacteria can multiply rapidly (4,5).

The most common spoilage bacteria in milk are lactic acid bacteria, which convert lactose (milk sugar), into lactic acid, causing the milk to sour and develop a tangy taste (4,6).

Additionally, other spoilage bacteria like Pseudomonas and psychotropic bacteria can thrive in cold environments, such as a refrigerator, and cause off-flavors and spoilage (4,5).

The milk sold today is pasteurized, meaning the milk is heated for a brief time to kill disease-causing bacteria. However, this process does not kill all bacteria. The sugar present in milk allows bacteria to grow and multiply, which will lead to spoiling (7). 

How can you tell if milk is spoiled?

Determining milk spoilage relies on sensory evaluation. Fresh milk should appear white and uniform in color, so if your milk exhibits distinct signs, it might have spoiled (8).

Spoiled milk can have a sour odor, which is a distinctive characteristic arising from the accumulation of lactic acid produced by bacterial activity. This transformation occurs when bacteria, such as lactic acid bacteria, ferment the lactose present in the milk, leading to an increase in acidity, and altering the milk’s taste and smell (4,6).

Additionally, visual cues may include a slight yellowish hue and a lumpy texture, while curdled chunks, clumps, or unusual discoloration can further indicate bacterial growth and degradation of milk proteins. These signs collectively indicate that the milk has undergone microbial spoilage (4,6).  

Remember, if the milk looks, smells, or tastes off, it is best to discard it to avoid any potential health risks associated with consuming spoiled milk.

What is the shelf life of milk?

The shelf life of milk primarily depends on its type and storage conditions. 

Pasteurized milk, the most common variety, typically has a shelf life of about 7 to 14 days when stored in a refrigerator at temperatures around 40 °F (4 °C) or lower (9). 

Ultra-high temperature (UHT) or ultrapasteurized milk, can last significantly longer, often up to 3 months and 3–9 months, respectively, if unopened and stored in the refrigerator. However, once milk is opened, regardless of type, it should be consumed within a few days to a week (5-7 days) to ensure freshness and safety (7). 

When frozen, milk can last for about 3 months under constant freezing temperature (10).

How can you properly store milk?

You can properly store milk following the guide below (7,11,12).

  • Store milk in the coldest part of the refrigerator at 40 °F (4 °C) or lower to maintain its quality and safety, since this temperature range inhibits the growth of most bacteria, including spoilage ones, and slows down enzymatic reactions. 

  • Do not keep milk in the door, as the temperature there is most unstable.

  • Place milk away from warm items in the refrigerator, as warmth can cause fluctuations and compromise the quality of milk.
  • Keep the milk container tightly closed to prevent contamination and minimize exposure to air, which can lead to bacterial growth and off-flavors.

  • If you don’t plan to use the milk within a few days, you can freeze it at 0 °F (-18 °C), but leave some room for expansion in the container, as milk can expand when frozen.


In this brief guide, we have answered the question, “What to do if I accidentally drank spoiled milk?”. Moreover, we also discussed how milk gets spoiled, how you can tell if milk is spoiled, and how to properly store it.


Was this helpful?

Thanks for your feedback!



Bintsis T. Foodborne pathogens. AIMS Microbiol. 2017;3(3):529-563.


Spiegel BM, Khanna D, Bolus R, Agarwal N, Khanna P, Chang L. Understanding gastrointestinal distress: a framework for clinical practice. Am J Gastroenterol. 2011, 106(3):380-5.


Lu M, Wang NS. Spoilage of Milk and Dairy Products. The Microbiological Quality of Food, 2017, .151-178


Dhakane R, et al. Spoilage and preservation of milk and milk products: A review. J Emerging Tech and Inn Res, 2019, 6. 


Teuber M. Lactic Acid Bacteria. In book: Biotechnology Set, Second Edition, 2008.


Meunier-Goddik L, Sandra S. Liquid Milk Products: Liquid Milk Products: Pasteurized Milk. Encyclopedia of Dairy Sciences (Second Edition), 2011, 274-280.


Tessema A, Tibbo M. Milk quality control. Technical Bulletin No. 2, 2009.


Garden-Robinson J. Food Storage Guide Answers the Question: How long can I store. North Dakota State University Extension Service, 2013. 


USDA. Refrigeration & Food Safety. 2015.


Tavman S, Yilmaz T. Freezing of Dairy Products. In book: Advances in Dairy Products, 2017.