Why do some people get sick after accidentally drink sour milk?

Consuming spoiled or sour milk can indeed lead to various adverse effects, including feeling sick. Here are some reasons why:

1. Lactose Intolerance: Lactose is the natural sugar found in milk. Some individuals have difficulty digesting lactose, a condition known as lactose intolerance. When they consume milk or dairy products, they may experience symptoms such as bloating, gas, abdominal pain, and diarrhea. Sour milk can often exacerbate these symptoms due to changes in the milk's composition and pH levels.

2. Spoilage-Related Bacteria: Sour milk results from the growth of bacteria that convert the milk's natural sugars (lactose) into lactic acid. While some bacteria used in the controlled fermentation of dairy products (like yogurt) are beneficial, the growth of harmful bacteria due to improper storage or contamination can lead to the presence of pathogenic microorganisms. These bacteria can produce toxins or cause infections, resulting in symptoms such as nausea, vomiting, abdominal cramps, and diarrhea.

3. Histamine Intolerance: Sour milk can contain higher levels of histamine, a compound released during bacterial fermentation. Some individuals have difficulty metabolizing histamine, known as histamine intolerance. Consuming foods rich in histamine, such as spoiled milk, can cause symptoms like headaches, flushing of the face, hives, and gastrointestinal issues like diarrhea and abdominal pain.

4. Food Poisoning: In cases of severe contamination, spoiled milk may contain harmful bacteria like E. coli, Salmonella, or Listeria. These bacteria can cause food poisoning, leading to more serious symptoms such as high fever, severe diarrhea, intense vomiting, and in extreme cases, hospitalization or even life-threatening complications.

5. Allergic Reactions: Some individuals may have an allergy or intolerance to milk proteins, such as casein or whey. Consuming any milk product, including spoiled milk, can trigger an allergic reaction in these individuals, causing symptoms like hives, difficulty breathing, wheezing, and in severe cases, anaphylaxis.

It's important to note that not everyone who accidentally consumes sour milk will experience adverse effects. Individual sensitivity, the extent of spoilage, and the type of bacteria present all contribute to the likelihood of developing symptoms. If you suspect you have consumed spoiled milk and feel unwell, it's advisable to seek medical attention, especially if you experience severe or persistent symptoms.