Why Do Onions Make You Cry?

Have you ever experienced teary eyes and a runny nose while cutting onions? If so, you’re not alone. The seemingly simple act of chopping an onion can turn into a tearful ordeal for many people. But why do onions make you cry? In this article, we will explore the fascinating science behind onion tears, the compounds responsible for this phenomenon, and various techniques to minimize your tears while enjoying the culinary benefits of this versatile vegetable.


Onions are a staple ingredient in kitchens around the world, appreciated for their unique flavor and ability to enhance a wide range of dishes. However, the moment you slice into an onion, you may find yourself shedding tears. This peculiar reaction has intrigued scientists and home cooks alike for centuries. Let’s dive into the science behind this common culinary conundrum.

The Science Behind Onion Tears

The primary cause of onion-induced tears lies in the biochemical composition of the vegetable. Onions contain volatile compounds that are released when the onion’s cellular structure is disrupted during cutting, crushing, or slicing. These volatile compounds then come into contact with your eyes, leading to the familiar stinging sensation and the release of tears.

Onion Structure and Tear-Inducing Compounds

To understand why onions make you cry, it’s essential to examine their structure and the specific compounds responsible for the tear-inducing effect. Onions consist of several layers, including an outer protective layer, fleshy edible layers, and a central bulb. Within these layers, two primary compounds contribute to tear production: amino acid sulfoxides and enzymes.

The Role of Enzymes in Onion Tears

Enzymes play a crucial role in the tear-inducing process. When an onion is cut or damaged, the onion’s cells are breached, and enzymes called alliinases are released. These enzymes trigger a series of chemical reactions that convert amino acid sulfoxides into sulfenic acids. One particular sulfenic acid, syn-propanethial-S-oxide (SPSO), is responsible for stimulating the sensory neurons in your eyes, leading to tear production.

The Onion’s Defense Mechanism

While onion tears may seem like an inconvenience to us, they actually serve as a defense mechanism for the onion. When an onion is cut or injured, the release of tear-inducing compounds acts as a deterrent against potential threats, such as insects or animals. This defense mechanism is the onion’s way of protecting itself from harm.

Factors Affecting Onion Tear Production

Although onion tears are a universal experience, the intensity of the reaction can vary from person to person. Several factors influence the level of tear production when cutting onions. Individual sensitivity, onion variety, storage conditions, and the onion’s age can all contribute to the variation in tear-inducing effects.

Tips to Reduce Onion Tears

While it may be challenging to completely eliminate onion tears, there are several techniques you can employ to reduce their impact. Here are some tips to help minimize onion-induced tears:

  1. Chill the onion: Place the onion in the refrigerator for 30 minutes before cutting to slow down the release of tear-inducing compounds.
  2. Cut near a running water source: Running water can help dissipate the volatile compounds released by the onion, reducing their contact with your eyes.
  3. Use a sharp knife: A sharp knife creates cleaner cuts and disrupts fewer onion cells, reducing the release of tear-inducing compounds.
  4. Ventilate the area: Proper ventilation can help disperse the onion’s volatile compounds, preventing them from accumulating in the air around you.
  5. Freeze the onion briefly: Freezing the onion for a few minutes before cutting can help inhibit enzyme activity, resulting in fewer tear-inducing compounds being released.

The Myth of Cutting Onions Underwater

You may have heard the suggestion to cut onions under running water or submerge in water to prevent tears. However, this technique is not as effective as it may seem. The water does not neutralize or absorb the tear-inducing compounds; instead, it might make the onion more slippery, increasing the risk of accidents.

Alternative Techniques to Minimize Onion Tears

If traditional techniques fail to alleviate your onion tears, you can explore alternative methods to reduce tear production. Some options include:

  • Wear goggles: Protective goggles or glasses create a barrier between your eyes and the onion’s volatile compounds, preventing them from reaching your eyes.
  • Use a fan: Positioning a fan near your cutting area can help blow away the tear-inducing compounds, reducing their contact with your eyes.
  • Light a candle: Lighting a candle near your cutting board can help burn off the tear-inducing compounds in the immediate vicinity.

Cooking Methods to Reduce Tear Production

While raw onions are most notorious for inducing tears, cooking onions can help mitigate their tear-inducing effects. Heat breaks down the tear-inducing compounds, reducing their potency. Sauteing, grilling, or caramelizing onions can significantly diminish tear production while still imparting their distinct flavor to your dishes.

Health Benefits of Onions

Beyond their tear-inducing properties, onions offer a range of health benefits. They are rich in antioxidants, vitamins, and minerals, and have been linked to various potential health advantages, including:

  • Heart health: Onions may help reduce the risk of heart disease by promoting healthy blood pressure levels and improving cholesterol profiles.
  • Immune support: The compounds found in onions have antimicrobial and anti-inflammatory properties that may strengthen the immune system.
  • Digestive health: Onions contain dietary fiber and prebiotics that support healthy digestion and gut bacteria balance.


Onions may bring tears to your eyes, but their culinary versatility and numerous health benefits make them a worthwhile addition to your kitchen. Understanding the science behind onion tears and employing practical techniques can help minimize the tear-inducing effects, allowing you to enjoy all that onions have to offer without shedding too many tears.


FAQ 1: Why do only some people cry while cutting onions?

Individual sensitivity to the tear-inducing compounds in onions varies. Some people have more sensitive eyes or produce fewer tears, resulting in a less intense reaction when cutting onions.

FAQ 2: Can wearing goggles prevent onion tears?

Yes, wearing goggles or protective glasses can create a barrier between your eyes and the tear-inducing compounds, preventing them from reaching your eyes and reducing tears.

FAQ 3: Do sweet onions make you cry less?

Sweet onions, such as Vidalia or Walla Walla onions, have a lower concentration of tear-inducing compounds, making them less likely to cause tears compared to pungent onion varieties.

FAQ 4: Are there any tricks to cutting onions without tears?

Chilling the onion, using a sharp knife, cutting near running water, or employing alternative techniques like wearing goggles or using a fan can help minimize onion tears.

FAQ 5: Can refrigerating onions reduce tear production?

Refrigerating onions can help reduce tear production to some extent. The lower temperature slows down the release of tear-inducing compounds, but it may not eliminate tears completely.

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