# Dented, Swollen or Expired Cans: Safe to Eat? · Larder & Well > Source: https://larderandwell.cc/food-storage/dented-cans-safe-to-eat Food storage ## Dented, Swollen and Expired Cans: Safe to Eat? A five-point check you can run on every can in the house, what the date on the bottom really means, and how to keep a can stockpile rotating so nothing reaches the bulging stage. By Ruth Calloway, November 15, 2026 A can with a shallow dent on its body, a few spots of surface rust you can rub off with a towel, or a date that has already passed is usually still safe to eat, as long as the seal holds and the ends are flat. A can that bulges, leaks, spurts when opened, carries a sharp dent or any dent on a seam, or is rusted deep into the metal goes in the trash unopened, because the botulism toxin it may hold cannot be seen, smelled or tasted. Your next step is simple: pull every can off one shelf this weekend and sort the cans with the [five checks below](#check). The rest of this page explains each check, what the dates mean, which cans hold up longest, and how to keep the stockpile turning over. ### The five-point can check Work through these in order with each can in your hand. A failure on any one of them settles it, and you do not need to go on to the next. 1. **Ends.** Both the top and the bottom should be flat or slightly sunken. Press the center of each. A lid that bulges, or flexes up and down under your thumb, fails. 2. **Rims and side seam.** Run a finger around the top rim, the bottom rim and down the soldered or welded seam on the side. Any dent that touches one of them fails. 3. **Dents on the body.** A shallow, rounded dent on the smooth side wall passes. A sharp crease, a point, or a dent deep enough to lay a fingertip in fails. 4. **Rust.** Light rust that wipes off with a paper towel passes. Rust that leaves pits, flakes, or sits on a seam fails. 5. **Leaks and stains.** Sticky residue, a stained label, or a crust around a rim means the can has been weeping. It fails, and so does any can that was sitting in that residue. One more check happens at the opener. If the contents spurt, foam or hiss out under pressure, or the food smells sour or looks moldy, stop there and treat it the way the section on [throwing out a bad can](#dispose) describes. The CDC lists all of those signs on its [botulism prevention page](https://www.cdc.gov/botulism/consumer.html), along with leaking, bulging, cracked and damaged containers. A shallow dent on the side wall can stay. A dent on the rim or a domed lid sends the can out unopened. ### Are dented cans safe to eat? A metal can keeps food safe for years because of its seal. The lid and bottom are rolled and crimped onto the body, and the side has its own seam. Food inside was heated after sealing to kill what could grow in it, and nothing new gets in as long as those joins hold. The body of the can is just a wall. A shallow push-in leaves both the food and the seal untouched. That is why the USDA Food Safety and Inspection Service only tells households to throw out cans that are [badly dented](https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/shelf-stable-food), and why extension guides draw the line at where the dent sits. Texas A&M AgriLife's [canned food safety sheet](https://dinnertonight.tamu.edu/cans-safe/canned-foods-is-it-safe/) says to discard a can with a dent deep enough to lay a finger in, or any dent on the top or side seam. A hard knock on a rim or the side seam can open a gap too small to see, and air and bacteria can follow. A sharp crease on the body can also crack the inner coating and start corrosion from the inside, which is why a crease counts against a can even when it misses the seam. If you cannot decide whether a dent touches the seam, count it as touching. For a stockpile, the practical rule is to move any dented can that passes to the front of the shelf and eat it within the next few weeks, rather than leave it to sit for years. It is the can most likely to rust from that spot later. ### Swollen cans and botulism: never open, never taste A can bulges because something inside is making gas. In a commercial can that should not happen, so a swollen end means either the seal failed and microbes got in, or the food was never fully processed. Either way, the bulge is the outside sign that something is growing in a sealed, airless space, and those are the conditions in which _Clostridium botulinum_ makes its toxin. Botulism from commercial cans is rare, and FSIS says so plainly. What makes it worth respecting is that the toxin has no warning of its own. The CDC notes that it cannot be smelled or tasted, so a swollen can of green beans that smells fine is still a swollen can. Tasting a spoonful to check is exactly what not to do. A frozen can is the one bulge with an innocent cause, and it still goes out. Utah State University Extension warns that freezing swells cans and may cause seam failures that let bacteria in. A case of soup left in an unheated garage over a hard winter is not worth the gamble once the ends have domed. Know the symptoms in case someone in the house has already eaten from a bad can. The CDC lists [double or blurred vision, drooping eyelids, slurred speech, trouble swallowing, dry mouth and muscle weakness](https://www.cdc.gov/botulism/symptoms.html), usually starting 18 to 36 hours after the meal. It is a medical emergency. Go to an emergency room, and take the can or its label with you if you still have it. Poison Control at 1-800-222-1222 can also advise. ### How to throw out a bulging or leaking can A bad can is a hazard in the kitchen trash, where a child or a dog can get at it, and opening it to empty it is how the contents end up on your hands. Follow the CDC's steps for [handling food you suspect of botulism](https://www.nnepc.org/national-news/practice-safe-canning-to-avoid-botulism): * Put on rubber or latex gloves before you pick it up. * Leave it sealed. Do not open, puncture or rinse it. * Put it in a sealable plastic bag, wrap a second bag around that, and tape it shut. * Put the bundle in an outdoor trash bin with a lid, out of reach of people and animals, and keep it out of the recycling. If it leaked onto the shelf or counter, wet the spot with a solution of a quarter cup of household bleach in two cups of water, leave it for 30 minutes, and wipe it up with paper towels that go in a bag of their own. Wash the shelf again normally, then wash your hands with soap for a full two minutes. ### How long canned food lasts past its date How long does canned food last past its expiration date? Longer than the label suggests. The date stamped on most cans is a best-by or code date set by the packer for quality. It is not a safety cut-off. Utah State University Extension, in its guide to [getting the most out of food storage](https://extension.usu.edu/news%5Fsections/home%5Ffamily%5Fand%5Ffood/get%5Fthe%5Fmost%5Fof%5Ffood%5Fstorage), says commercial canned food stays safe as long as the seal is unbroken, and that best quality usually runs two to five years from the day the can was filled. Where in that range a can falls depends mostly on acid. FSIS gives high-acid foods such as tomatoes, fruit, juice, pickles, sauerkraut and vinegar sauces 12 to 18 months of best quality. Low-acid foods such as meat, poultry, stews, corn, carrots and peas get two to five years. Acid slowly works on the can's lining, so the high-acid cans are the ones that show their age first, with softer fruit, a metallic taste and, eventually, pinholes from the inside. Past those windows, the food loses quality while the seal keeps it safe. Colors dull, vegetables soften, and USU puts the vitamin loss for A and C at 5 to 20 percent a year even in a sealed can. Minerals, protein and calories stay. The famous long-shot case is the steamboat Bertrand, which sank in the Missouri River in 1865\. Chemists from the National Food Processors Association tested its recovered cans in 1974 and [found no microbial growth](https://www.foodreference.com/html/cans-extreme.html), though the food had lost much of its smell and some nutrients. That does not mean a ten-year-old can from the back of the closet is a good meal. It means the date alone is no reason to throw it out. Run the five-point check, open it, and judge it by look and smell before you eat. Our [food storage shelf life chart](/food-storage/food-storage-shelf-life-chart) lists the canned food windows beside rice, flour, oil and the rest of the pantry, so you can see which shelf each item belongs on. ### What shortens canned food shelf life Heat, moisture and freezing do more damage to a can store than time does. FSIS warns that storage above 90 degrees damages canned goods and tells households to keep cans out of spots above the stove, under the sink and in damp basements. USU cites USDA figures that shelf life roughly halves for every 11 degrees the room warms up, which makes a closet inside the house worth far more than a hot garage. Damp air rusts the bottom rim first, which is the part you never look at, and it is where the date code is printed. Keep cans on wooden or wire shelves rather than on a bare concrete floor, and run a dehumidifier in a basement that sweats. Each of these appears with its fix in our list of [food storage mistakes that quietly ruin a stockpile](/food-storage/food-storage-mistakes). ### Home-canned jars follow different rules Home-canned jars have no factory process behind them, so they get a shorter clock and a stricter check. USU recommends eating home-canned food within a year and using it before two. Before opening a jar, check that the lid is still concave and does not flex, and that nothing has crept out under the band. Low-acid home-canned food such as beans, corn, meat and stock is where most botulism cases in this country start, so it only comes off the shelf if it was pressure canned with a tested recipe. Our guide to [pressure canning for beginners](/homestead/pressure-canning-for-beginners) covers the safe method, and the page on [open-kettle canning](/old-ways/is-open-kettle-canning-safe) explains why the old shortcuts are not safe for any jar you plan to store. ### The best canned food to stockpile for long storage Since acid sets the clock, the cans that hold up longest are low-acid foods with real calories in them. The list below is in no particular order. Pick the ones your household already eats, because a can nobody opens is wasted space. * **Canned meat and fish.** Chicken, beef, pork, tuna, salmon and luncheon meat sit in the two-to-five-year group and carry the protein and fat that bulk rice and beans lack. * **Beans.** They come already cooked, which saves the hour of simmering that dry beans need when fuel is short. * **Starchy vegetables.** Potatoes, corn, peas and pumpkin give more calories per can than green beans or spinach. * **Soups, stews and chili.** A full meal in one can, useful on the days nobody has the time or the fuel to cook. Tomatoes, fruit, fruit juice and pickles still have a place. They supply acid, vitamin C and variety that a shelf of meat and beans cannot. Buy them in the amounts you will use within a year, and expect to turn them over faster. Cans also work as a bridge layer between the freezer and the deep store. When the power goes out, you eat from the freezer first, using the hold times in our guide to [what to keep when the freezer loses power](/food-storage/freezer-power-outage-how-long-food-lasts), then from the can shelf, and only after that do you start on the sealed buckets. To size how many cans that middle layer needs, the [family-of-four food storage guide](/food-storage/how-much-food-to-store-for-a-family-of-four) works through the calorie budget. ### Rotating canned goods so nothing gets old Rotation is the habit that makes the five-point check rare. The method preppers have used for decades is first in, first out: new cans go in at the back, and you always cook from the front. [OffGridWeb's explanation of FIFO](https://www.offgridweb.com/preparation/fifo-a-principle-every-prepper-should-know) puts it in one line: older stock at the front, newer stock at the back. * **Write the month and year on every lid** with a fat marker as you unpack groceries. Code dates are hard to read and some brands skip them. * **Shelve by type, one row deep per item**, so the oldest can is always the one in front of you. * **Use a gravity rack** if you have the wall space. These sloped can racks feed the oldest can forward as you take one, and a simple homemade version from plywood rails does the same job. * **Give high-acid cans their own shelf** near the kitchen, since they have the shorter window. * **Inspect as you rotate.** Every time you restock, glance at the ends and rims of the cans on that row. A bulge caught early is one can lost, not a stained shelf. The simplest buying rule is to buy two of each item you open and put both at the back. The store grows on its own, and every can on the shelf gets used inside its window. ### My take: what I would toss and what I would keep I would bin any can with a bulge, a leak, a dent on a rim or a crease without a second thought, and I would not open it to check. One can of chili costs little. A week in intensive care costs everything. A shallow dent on the side, a freckle of surface rust or a date two years gone would not stop me. I would move those cans to the front and eat them soon. For the stockpile itself, I would build around low-acid meats, beans and soups the family already likes, mark every lid as it comes in, and do a full shelf check each spring and fall. Before buying more, I would run the household through our [family food and water storage calculator](/food-storage/family-food-and-water-storage-calculator) to see how many weeks the can shelf actually covers. Then start with the shelf you have: take it down, run the five checks, and put it back in date order. ### Sources * [USDA Food Safety and Inspection Service: Shelf-stable food safety](https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/shelf-stable-food) * [CDC: Preventing botulism](https://www.cdc.gov/botulism/consumer.html) * [CDC: Symptoms of botulism](https://www.cdc.gov/botulism/symptoms.html) * [Northern New England Poison Center: Practice safe canning to avoid botulism](https://www.nnepc.org/national-news/practice-safe-canning-to-avoid-botulism) * [Texas A&M AgriLife Dinner Tonight: Canned food safety sheet](https://dinnertonight.tamu.edu/cans-safe/canned-foods-is-it-safe/) * [Utah State University Extension: How can I get the most out of my food storage](https://extension.usu.edu/news%5Fsections/home%5Ffamily%5Fand%5Ffood/get%5Fthe%5Fmost%5Fof%5Ffood%5Fstorage) * [FoodReference: Canned food in extreme cases (steamboat Bertrand)](https://www.foodreference.com/html/cans-extreme.html) * [OffGridWeb: FIFO, a principle every prepper should know](https://www.offgridweb.com/preparation/fifo-a-principle-every-prepper-should-know) How we write: we work from USDA, CDC, extension and university guidance, and we say what we have not tested. See our [editorial policy](/editorial-policy). ### Damaged can questions Can I cook a swollen can long enough to make it safe? No. Do not open it at all. Opening a bulging can can spray its contents onto you and the counter, and the toxin is the reason it went out of the pantry in the first place. Is a can with a small dent from the grocery store fine to buy? If the dent is shallow, rounded and away from both rims and the side seam, the food inside is generally fine. A crease or a dent touching a rim is a reason to leave it on the store shelf. Do canned goods go bad in a hot car or truck? Heat speeds up the loss of flavor, color and texture, and USDA warns that storage above 90 degrees damages canned goods. A few hot days will not spoil a sound can, but a summer behind the seat will age it years. What if the lid only flexes when I press it? A lid that pops up and down under your thumb has lost its vacuum or is starting to swell. Treat it as a bulging can and bin it without opening. How often should I go through the canned food shelf? Twice a year works for most households: once in spring and once in fall, when you are already changing clocks or smoke alarm batteries. Written by Ruth Calloway Pantry, water and homestead skills Ruth Calloway writes Larder & Well's guides to food storage, water, off-grid power and the old household skills. She works from extension-service bulletins, USDA and Ready.gov guidance, manufacturer manuals and years of homesteader discussion threads, and she says plainly where the sources disagree. She does not claim to have tested what she describes; when a method is untested or risky, her articles say so. [rcalloway@larderandwell.cc](mailto:rcalloway@larderandwell.cc) Last checked 2026-11-15 More on building a pantry that lasts is in the [food storage section](/food-storage). --- [Larder & Well](/) Keep the household fed, watered and warm when the stores close. Food storage, water, off-grid power, homestead skills and the old ways, written for American households that want to stay fed, watered and warm when the grid, the economy or the supply chain fails. [Send a correction or a question](/contact) © 2026 Larder & Well. Independent, written from sources you can open. A page that ever carries a paid link says so above it. Nobody pays for a place in our guides.