Is It Safe to Use a Knife With Rust Spots?

Any object we use will start to show their wear the more we use them. Speakers might not sound as clear or play as loudly, while dinner plates might begin to crack and chip. Some damage and wear and tear do not make the object unusable, but that is not the case for all items.

It is not safe to use a knife with rust spots, especially for food preparation. If your knife has rust spots on it, you should refrain from using it. Ingesting larger amounts of rust or cutting yourself with a rusty knife can seriously harm a person and cause them to develop a nasty bacterial infection.

In this article, we will express why you should not use a rusty knife. We will also provide three methods for salvaging your rusty knife and preventing you from becoming sick.

Using a knife with rust spots.

The Harmful Effects of Rust on a Person’s Health

There are some substances like rust that we can ingest tiny amounts of without getting sick. However, if you consume a bigger piece of a sharp knife, it could lead to serious health issues.

Cutting yourself on something rusty puts you at risk of developing tetanus, a bacterial infection that can be fatal if left untreated.

These are all common symptoms of tetanus:

  • Jaw cramping
  • Seizures
  • Severe muscle contractions

If you have been cut by anything rusty, we recommend an immediate trip to the emergency room. If you are not up to date on your tetanus shot, you will receive one, which will help decrease your risk of developing tetanus.

Though the tetanus vaccine is one that you must keep up to date on, we recommend keeping up with it. This is particularly crucial if you work around items that can become rusty and can cut you.

You can lower your risk of getting tetanus by always wearing protective gear when you work. Additionally, be sure to cover up existing wounds with bandages.

If you notice that your knives, utensils, or other materials are rusty, safely removing the rust will also lower your risk of possibly getting tetanus.

Remove the Rust From a Knife

Though rust can be harmful if ingested or cut with, it is also a problem to which you can find a resolution relatively quickly.

Just because your knife has developed rust does not mean you have to throw it away. In fact, with the proper rust remover, some time, and a little patience, you can get that rusty knife back to good as new!

Though some people might use chemical rust removers to remove rust, we recommend leaving those for items that aren’t related to food preparation. With this in mind, our recommendations will be more natural. In fact, many of the following methods involve items you already have around your home!

Here are our top three suggestions for removing rust from a knife:

Use a Potato To Remove Rust With the Help of Natural Oxalic Acid

Potatoes have a high oxalic acid count, making them an excellent natural way to remove rust from your knife. Who would have thought that the versatility of the potato isn’t limited to its role as an ingredient?

The potato method is super simple to do:

  1. Stick your rusty knife in the potato, ensuring no rusted areas are left exposed.
  2. Let the knife sit for a few hours or more.
  3. After the allotted time, remove the blade from the potato and give it a good wipe down with some oil. The rust should be gone.

We do not recommend using the potato for cooking once it has been used for rust removal.

Cut Onions To Remove Rust via Natural Sulfenic Acid

Onions have a high sulfenic acid count, making them effective for removing rust from knives (and making us cry in the process).

This process is super simple. Use the rusty knife to cut some onions, making sure to slide the blade across the onion as you slice. This technique is effective for knives with only a few spots of rust.

Rub Lemons or Lemon Juice Across the Rusty Blade

Lemons are high in acidity, making them an excellent choice for cleaning the rust off knives or any other rusty object.

For this method, cut your lemon and carefully rub it across the blade. If you need some extra abrasion, put some salt on the lemon before applying it to the blade. Once the rust has been removed, clean the blade with dish soap and water and dry it with a cloth.

You can also squeeze lemon juice onto the blade and leave it to sit for two to three hours. When time is up, check the blade. If the knife is rust-free, clean and dry it as you normally would.

Lemons are great for all sorts of around-the-house cleaning. So, you can reuse the lemon for household cleaning projects as well!


It is not safe to use a knife with rust spots on it. If you have recently used a rusty knife when cooking, we recommend seeking medical attention as a safety precaution to decrease your risk of contracting tetanus.

If you were fortunate enough to notice the rust before using the knife, do not throw the knife away! You can save it and make it safe to use again, saving time, money, and a trip to the emergency room.

And if you’re looking to buy a new knife set that won’t rust, make sure you check out our recommendations.

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