Can Peanut Butter Go Bad? What Happens if you Eat Expired Peanut Butter?

Does Peanut Butter Expire?

Peanut butter can be considered as one of the most common and essential items in any modern household, whether it is used to make a delicious afternoon sandwich snack or a quick school lunch for the kids. With our busy schedules and hectic lifestyles, such ready-to-eat items have become very common and often come in handy to snack on.

Does it, however, mean that you could stock up on a year’s supply of peanut butter and never worry about it going bad? Does peanut butter expire? Read on to find out how to store this really useful item and prolong its shelf life.

Does Peanut Butter Go Bad?

The question is, does peanut butter go bad? The answer to this can be found in the composition of the peanut butter. The key ingredient in peanut butter is the peanut oil that prevents it from going bad for quite some time. As a result of the high oil content, peanut butter has much less water, a key factor in the growth of bacteria and fungi.

Since water is almost absent, the peanut butter will not go bad due to a bacterial contamination but there are chances of it going rancid due to oxidation.

If stored for six months or more, there might be a separation of oil. It can easily be fixed by stirring the jar with a spoon and the peanut butter is good to use.

What Exactly Happens When Peanut Butter Goes Bad?

Oxidation can cause it to go rancid, which means that the taste changes and it begins to give off a particular odor that may not be appetizing to all. The more oxygen the peanut butter is exposed to over its lifetime, the more its taste and smell are spoiled and it becomes unfit for use.

There is, however, a natural guard against this. The vitamin E present in the peanut butter acts as an antioxidant and helps prolong its shelf life, according to a senior scientist from England. Usually, this process does not begin until about nine to 12 months from purchase. This is why the jar comes with a “Best if used by” date on its label.

How to Tell If Peanut Butter Has Gone Bad?

So, while you were cleaning your refrigerator, you found a jar of peanut butter that has been lying there for some months and are not sure if you can still go ahead and enjoy it in a sandwich or a hot dog?

There are ways to determine if peanut butter is good or bad. The first and important thing to do is to look at the conditions in which this jar and other food items around it are stored.

1. Visual and olfactory checks

A good look at the peanut butter jar is the first thing that you should do. Sight gives you a good measure of whether the food is good or bad. In its normal and edible state, peanut butter is soft and creamy.

If it has gone bad, it will tend to be dry and hard. The shade may be a tad darker and its pleasant aroma changes to a rancid one. If any of the above are seen, it is best to toss the jar in the bin.

2. Separation of oil

Another condition that is seen frequently is the separation of oil, which tends to rise up and form a separate layer above the butter in the jar. If the amount of oil is more than the butter, the jar is soon to go bad or has already gone bad and it must be discarded immediately.

If the oil is not too much, it can be easily stirred back into the butter to form a soft gooey paste that it once was. The peanut butter can be safely consumed. It is, however, not advisable if the taste has changed or if the smell is even a bit on the rancid side.

Shelf Life of Peanut Butter & How to Store It

So what is the ideal shelf life of peanut butter and how to store it such that its life is prolonged?

The ideal way to extend its life is to refrigerate peanut butter as soon as you open the jar. This extends the life of the processed jar which contains a number of preservatives.

As long as it is stored, the peanut butter must be kept in a closed jar with a tight lid; whether it is store-bought or homemade.

Preserving homemade peanut butter

If you make it at home, the peanut butter must be kept in a tightly closed container when not in use, and to be on the safe side, refrigerate this jar immediately.

Just take out the jar a couple of hours before you want to actually use it and the butter will come to room temperature and be soft enough for you to spread it on the sandwich or the hot dog. Even if you forget to refrigerate it again after use, it is fine. You can do so whenever you remember.

Another tip to keep it edible for extended periods is to use clean spoons and butter knives when you take it out of the jar to avoid cross-contamination. They should be essentially dry without even a drop of water.

A Word of Caution Regarding Store-Bought Peanut Butter

If you have to buy ready-to-eat peanut butter, do check the list of ingredients on the jar thoroughly. These should contain at least 90% peanuts. Also, they have a lot of added oils, emulsifiers, sugar, and other additives. Avoid these as much as possible and opt for one without too many preservatives and added oils.

The oil in it should be the natural peanut oil. It is best if you can find out where the peanuts were grown and that they are not genetically modified or heavily sprayed with pesticides.

Also, check for the levels of aflatoxins in the peanuts as these are really harmful to your health. So, the quality and shelf life of peanut butter may be based on the way the peanuts are grown!

What Happens If You Eat Expired Peanut Butter?

Technically, peanut butter expires or becomes unfit for use if it has gone hard and dry and smells rancid. It will not have bacteria or fungus-like the normal butter.

Many times, people do not even realize that they are consuming expired food as the taste hardly differs. It is, however, not advisable to do this. Also, those who are allergic to peanuts should avoid eating peanut butter, whether it is good to eat or expired.

The most common side effect of eating a bad peanut butter jar or an expired peanut butter sandwich is salmonella infection.

  • The first symptom is severe diarrhea accompanied by abdominal cramps. It is critical to remove the salmonella from the intestinal tract and our body’s natural way of doing it is through diarrhea. However, it is important not to dehydrate, so consult your doctor immediately.
  • In some cases, symptoms such as nausea and vomiting may occur. Drinking plenty of fluids is advised to prevent any dehydration and complications due to the same.
  • It is definitely time to consult your doctor if nothing stays in the stomach for long or if you notice any traces of blood in the vomit.

Conclusion on Peanut Butter Gone Bad & Storage Method

In conclusion, this tasty and healthy snack companion can be used very effectively in sandwiches, burgers, and hot dogs and helps make a quick snack or a lunch conveniently. It also packs the goodness of peanuts in it.

Refrigerating an open jar to prolong its shelf life will allow you to save on buying this item frequently. However, be aware of these simple tips and save it from going bad leading to any health-related emergencies.


Live Science Staff, “Can Peanut Butter Go Bad?”, September 28, 2012;, last accessed September 5, 2017
“How Long Does Peanut Butter Last?”, last accessed September 5, 2017
Megan Smith, “Signs & Symptoms of Food Poisoning From Peanut Butter”, August 14, 2017;, last accessed September 5, 2017
“Here’s What You Don’t Want To Know About Your Peanut Butter”,, last accessed September 8, 2017