Can out-of-date milk make you sick?

In this article, we will answer the question “Can out-of-date milk make you sick?”, and how long does it take for milk to spoil at room temperature?

Can out-of-date milk make you sick?

Consuming out-of-date milk in large quantities can make you sick. Common symptoms of food poisoning as a result of consuming out-of-date milk include diarrhea, vomiting, nausea, and stomach pain. 

If the symptoms do not go away in three days or in case of severe dehydration, consult your doctor. Read on If you want to know why milk spoils and how long it lasts after the expiry.

How long does it take for milk to spoil at room temperature?

Milk is perishable and should not be left unrefrigerated for more than 2 hours at 4°C and 1 hour if the temperature is above 32°C according to the FDA, or else the milk will spoil quickly. The crux is to never leave your perishables for long periods of time in the ‘danger zone.

The extent of spoilage of the milk that has been left on the counter depends a lot on the milk quality. Raw milk tends to spoil quicker than pasteurized milk. Milk with a higher initial microbial load will be more prone to spoilage even after pasteurization.

Why does milk spoil?

The two species of bacteria that spoil milk are lactobacilli and streptococci. Both of these species are thermostable, hence, they survive during pasteurization and multiply when the environment is favorable. 

When the milk suffers fluctuations in temperature, streptococci starts to multiply and produce acid by fermenting the milk’s sugar, lactose. This results in a decrease in the milk ph that inhibits the further growth of streptococcus.

After this, the lactobacillus takes hold and continues to make acid until it cannot multiply anymore due to low acidity. This low pH denatures the casein protein structure and causes it to curdle up leaving behind the whey protein liquid and the casein is filtered to make cottage cheese.

How to tell if that milk has gone bad?

Sour milk develops a slimy and grainy texture due to the curdling of casein protein. If the appearance has not changed yet, give it a sniff. If the milk smells sour and acidic, it has gone bad and is unfit for consumption

Drinking spoiled milk in large quantities can result in food poisoning that reflects in the form of diarrhea, vomiting, and nausea.

What should you do with spoiled milk?

If your milk has gone bad and you do not want to waste it, there are plenty of options for recycling it. If the milk has started to turn sour, add a little acid, and make cottage cheese from it. 

The leftover whey water can be used to cook pasta, soak grains to make them more palatable, or use as an alternative to liquid when baking cakes, muffins, or cookies.

It can also be added to your broth, marinades, or smoothies to get a protein boost.

How long does milk last after the sell-by date?

There is a difference between ‘Best-by’, ‘Sell-by’, ‘Use-by’, and ‘Expires on’ dates. Milk, If stored correctly, remains safe to consume even after the ‘Best-by’ date.

‘Expires on’ refers to the date on which the quality degradation speeds up and after that date, the product might not remain safe for consumption. 

The ‘Sell-by’ date is of importance to the seller. This date decides how long the product can safely stay on the shelves. Expiration dates vary with how the milk was processed, packaged, and stored.

Other FAQs about Milk which you may be interested in.

Can spoiled milk make you sick?

Can milk kill you?

How many cups are equal to a can of evaporated milk?

How long is the milk safe to drink after the expiration date?

Typically, unopened milk will last for 5–7 days past the labeled date, while opened milk will stay good for at least 2–3 days past this date. UHT milk that is sold unrefrigerated is also called aseptic milk. 

This type of milk can typically stay good for 2–4 weeks past the labeled date if stored in a cool, dry place such as the pantry, and up to 1–2 months in the fridge. Once opened, UHT milk should always be kept in the fridge and consumed within 7–10 days.

UHT milk is heated above 135°C for 2-5 seconds to kill the vegetative spores. Therefore, It has an extended shelf life than HTST milk.

Past printed date 
Lactose-free milk7-10
Non-fat milk7-10
Skim milk7
Reduced-fat 7
Whole milk 5-7
Past printed date 
All types of milk5-7


In this article, we answered the question “Can out-of-date milk make you sick?”, and how long does it take for milk to spoil at room temperature?



Hello, I'm Sana Ameer. I'm a student of Food Science and Technology at UVAS. I like to bake and I aspire to become a Food blogger.