When Should You Throw Away Canned Food? A Complete Guide

November 11, 2025 •

4 min read

According to the USDA, commercially canned foods are safe indefinitely if stored properly. However, the date on the can indicates quality, not safety. Knowing when should you throw away canned food is critical, as a bulging can, for instance, can indicate the presence of deadly botulism bacteria.

Quick Summary

This guide explains the key signs indicating spoiled canned food, including can damage, strange odors, and texture changes. Prioritizing physical condition over printed dates ensures safety.

Key Points

Inspect the can's exterior: Discard any can that is bulging, leaking, or has deep dents or heavy rust, as these indicate a compromised seal and possible contamination.
Ignore the date, trust your senses: 'Best by' dates are for quality, not safety. Upon opening, throw out contents with foul odors, foaming, or discoloration.
Watch for botulism signs: A bulging or swollen can is a critical warning sign of gas-producing bacteria like Clostridium botulinum; do not taste the food.
Know food types: High-acid foods (tomatoes, fruits) have a shorter quality lifespan (12-18 months) than low-acid foods (meats, vegetables) (2-5 years).
Store properly: Keep cans in a cool, dry, dark place to preserve quality and prevent rust. Avoid storing near heat sources or in damp areas.

Understanding Best-By Dates and True Shelf Life

The dates printed on commercial canned goods are often misinterpreted. Phrases like 'best by,' 'use by,' and 'sell by' are manufacturer suggestions for peak quality and flavor, not safety cut-offs. The United States Department of Agriculture (USDA) states that shelf-stable foods are safe indefinitely as long as the can itself remains in good condition. The true shelf life depends on the food's acidity and proper storage, not the calendar date.

High-Acid Foods: Items like tomatoes, fruits, pickles, and sauerkraut have a shorter quality shelf life. The acidity can react with the can over time, changing the food's taste and texture. For best quality, the USDA recommends using these within 12 to 18 months.
Low-Acid Foods: This category includes most vegetables, meats, poultry, and fish. These foods can maintain their quality for two to five years, and often much longer, provided the can is undamaged.

While the contents of a ten-year-old, perfect-looking can may be safe to eat, their nutritional value, flavor, and texture will have diminished. Proper rotation using the First-In, First-Out (FIFO) method is the best practice for maintaining food quality.

Critical Visual Cues That Demand Disposal

The most important indicators of food safety are the physical condition of the can and its contents. Ignoring these signs can lead to severe illness, including botulism, a rare but deadly form of food poisoning caused by the bacterium Clostridium botulinum.

Bulging, Swollen, or Leaking Cans

Any can that appears bloated, swollen, or is leaking should be discarded immediately without opening. This is the most dangerous sign of spoilage, as it often indicates gas production by bacteria, possibly botulism. Even a minute amount of the botulinum toxin is lethal, and you cannot see, smell, or taste it. Therefore, if a can shows any signs of swelling, it is a non-negotiable hazard.

Deep Dents and Damaged Seams

While minor, small dents are usually not a concern, severe dents are a different story. The USDA advises against using cans with deep dents, especially if they are along a seam. A dent of half an inch or more can break the can's hermetic seal, allowing bacteria to enter. A broken seal means the food is no longer sterile and can spoil. If a can has a deep or sharp dent, particularly on the top or bottom seam, it should be considered compromised.

Severe Rust or Corrosion

Light, surface rust that can be wiped off with a cloth is generally harmless. However, if the rust is extensive and causes pitting or deep corrosion, it can create a tiny hole in the can's body, allowing contaminants to enter. Any can with heavy, unwipeable rust should be discarded. The same goes for the inside of the can once opened; if the interior shows significant corrosion, throw it away.

Signs of Spoilage Upon Opening

If the can's exterior seems normal, the next step is a sensory evaluation upon opening. If you observe any of these signs, do not taste the food and dispose of it immediately:

Foul Odor: A bad, sour, or putrid smell is a definitive sign of spoilage.
Foaming or Spurting Liquid: The presence of bubbles, fizzing, or liquid that spurts out indicates gas buildup from bacterial growth.
Discoloration or Mold: Any unnatural color, cloudiness, or visible mold is a clear warning sign.
Slimy or Mushy Texture: Food that has an unusually soft, slimy, or disintegrated texture should be discarded.

Comparison Table: Safe vs. Unsafe Canned Food


Feature	Signs It's Still Safe	Signs It's NOT Safe
Appearance of Can	Unblemished, small surface dents away from seams, label intact	Bulging, swollen, or leaking can
Dents	Small, shallow dings that don't affect seams or seals	Deep dents (0.5+ inches) or dents on seams
Rust/Corrosion	Light, surface rust that can be wiped clean	Heavy, pervasive rust or corrosion
During Opening	Standard 'pop' of the vacuum seal	Liquid or foam spurts out, hissing sound
Appearance of Contents	Normal color, no signs of mold or sediment	Discoloration, cloudiness, or mold visible inside
Smell of Contents	Normal, as expected for the food	Foul, sour, or 'off' smell
Texture of Contents	Standard texture for the product	Excessively mushy, slimy, or disintegrated

Proper Disposal and Aftercare

If you find a can that meets any of the criteria for disposal, handle it with extreme caution. For cans with swelling or leaks, it is safest to throw the entire unopened can in the regular trash. Do not puncture it. If a spoiled can has been opened and spilled, wear gloves and clean the area thoroughly with a bleach solution (1 part bleach to 10 parts water) to neutralize any potential botulism toxins. Always wash hands and any kitchen surfaces that may have come into contact with the spoiled food. Store all canned goods in a cool, dry, dark place below 85°F to maximize their shelf life and prevent premature spoilage.

Conclusion

While canned foods are a resilient and long-lasting pantry staple, their safety is not guaranteed indefinitely. The 'best by' date is a guide for quality, not a rule for safety. The primary safety check is always a thorough visual and sensory inspection of the can and its contents. Crucial warning signs like bulging, leaking, or deeply dented cans must never be ignored, as they can indicate deadly botulism. Always remember the simple, life-saving mantra: when in doubt, throw it out.

For more information on safe home food preservation, you can visit the National Center for Home Food Preservation at the University of Georgia.

Frequently Asked Questions

Yes, generally you can. The 'best by' date is an indicator of peak quality, not safety. As long as the can is in good condition—no rust, dents, or bulging—the food should be safe to eat, though its flavor and texture may have diminished.

A bulging or swollen can is the most dangerous sign. This is often caused by bacteria like Clostridium botulinum producing gases inside the can, which can lead to botulism. Never open or taste the contents of a bulging can.

Not all dents are dangerous. Small, shallow dings away from the seams are usually fine. However, you should discard any can with a deep dent (more than half an inch), especially if it's on a seam, as this can break the seal and let bacteria in.

It depends on the severity. Light, surface rust is typically harmless and can be wiped away. Heavy, pitted rust or corrosion, however, can compromise the can's integrity and is a sign that it should be thrown out.

If you open a can and the contents have a foul odor, foam, or appear discolored, do not eat it. These are clear signs of spoilage. Discard the food immediately, and do not taste it.

After opening, leftovers from low-acid foods (vegetables, meat) should be refrigerated and used within three to four days. High-acid foods (fruits, tomatoes) can last five to seven days. Transferring the contents to a clean, non-metallic container is recommended.

Discard the entire sealed can in the trash. If the contents have spilled, wear gloves and clean the area thoroughly with a diluted bleach solution (1 part bleach to 10 parts water) to eliminate potential botulism toxins.