How Do You Know if Milk Is Spoiled — and Is It Safe to Drink?

When it comes to drinking milk, the date on the carton might not reflect the freshness of the product inside. The date you find stamped on a milk bottle or carton is the "sell-by" date, and the milk inside still might be fresh in the days to follow. However, you could end up with expired or spoiled milk in your fridge if your milk is stored or handled incorrectly.

Milk can be a nutritious drink but make sure you keep it in the fridge! (Image: Getty/AleksandarNakic)

Why Does Milk Spoil?

As you may already know, most milk available at common grocery stores has been pasteurized — a process of heating the milk to kill off pathogens, according to the Food and Drug Administration. However, even this process can't kill all the bacteria, and when the bacteria left behind continue to grow, they eventually causes the milk to spoil, according to August 2018 research published in the Journal of Dairy Science.

Raw milk, on the other hand, hasn't been pasteurized and therefore may contain dangerous microorganisms like salmonella, E. coli and listeria, according to Raw milk is not legal in all states.

How to Tell if Your Milk is Spoiled

While many believe milk shouldn't be consumed after the date printed on the carton, it is generally safe to drink past the sell-by date, according to the Dairy Council of California. While there is no hard or fast rule regarding milk expiration, a surefire way to check for freshness is to give the carton a whiff. Often, when milk spoils, the odor is strong and pungent. Even taking a small taste can help you determine if milk has gone bad.

The way you store your milk can help guarantee freshness for longer. The Dairy Council of California advises storing milk at a temperature between 38 and 45 degrees Fahrenheit. After you buy your milk from the grocery store, drive home to refrigerate it immediately; don't leave it in the car, especially if it's a hot day. Also avoid leaving the carton out on countertops or tables for long periods of time.

Even if you've done everything right, milk will eventually go bad. As a general rule of thumb, always give the container a sniff if it is past the sell-by date. If you're ever unsure as to whether or not your milk is spoiled, it's probably wiser to toss it — better safe than sorry!

What Are the Consequences of Drinking Spoiled Milk?

Unfortunately, drinking spoiled milk can take quite the toll on your digestive system. Food poisoning is no joke and can cause vomiting, stomach cramps and diarrhea. Depending on the food (and your body), food poisoning can occur several hours — or even several days — after drinking spoiled milk. Most often, food poisoning is mild, and symptoms will pass within a day or two.

In some cases, especially if you consumed raw milk, food poisoning can be more concerning, according to Kids Health. If the symptoms persist or you begin to experience signs of dehydration (like dark urine or no tears when a child is crying, according to the Mayo Clinic), it's probably best to take a trip to the doctor. Your doctor can test for potentially harmful germs like salmonella or E. coli and recommend different treatments depending on the results of those tests.

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