When your milk expires, you probably know what to do — dump that sh*t down the drain! Ditto for anything in your fridge that has gone a bit green. But what about vitamins? Do they expire? How would you know?

Expired vitamins and supplements become less potent as they break down over time.

Let’s break down how to keep your vitamins fresh longer and how to get the nutrient boost you’re looking for.

As with most things, it depends. The “use by” date on the bottle doesn’t quite cover it.

For starters, the FDA doesn’t require makers of dietary supplements to include an expiration date on the label as long the label “is supported by valid data demonstrating that it is not false or misleading.”

That means there may not be an expiration date on your chewable dino multivitamins at all. And if there is one, it’s probably a conservative estimate, since manufacturers don’t want to say your vitamins are good for several years if they don’t have the data to prove they’re as potent as the label claims.

Labels and dates aside, several factors affect how long vitamins are effective.

Solid formulations (like pills and capsules) degrade more slowly than gummies or liquid formulas.

Chemical properties of the ingredients used, such as the pH level, metal ions, and oxidizing and reducing agents, also play a role in shelf stability.

Because the FDA doesn’t require supplements to be researched in the same way as prescription and over-the-counter (OTC) medications, there are few studies on the potency of vitamins over time.

One study evaluated vitamins across different brands and found that 90 percent of samples of vitamins A, C, and E had significantly degraded after a year in storage.

The expiration (or “best by” or “use by”) date on a supplement bottle means the manufacturer guarantees the vitamin is fully potent until that date. After that, it may or may not be as potent, but no promises.

Even if vitamins languish for years in a dark bathroom cabinet, they don’t transform into anything unsafe. They just stop working.

Likely, nothing will happen if you take out-of-date vitamins… but that’s kinda the problem. You’re presumably taking vitamins for some health benefit, right? Over time, vitamins will become less and less potent, so you might not get the benefits you’re looking for in an old bottle.

While vitamins generally won’t become dangerous with age, if you notice a weird change in smell or appearance, toss that bottle and get a new one.

You may be wondering, what do I do with all these old vitamins? Flush them, dump them in the trash, or what? According to the FDA, the safest way to dispose of prescription or OTC medications is to drop them off at a drug take-back location.

The Environmental Protection Agency advises against flushing medications and supplements down the toilet or drains. And putting them directly in the trash may pose a risk to children or animals.

The shelf life of vitamins can depend a lot on where you store them. The best storage spot is probably not where you think!

First, read the label. Some manufacturers may indicate the best environment for storing their products. Most vitamins need to be protected from light, heat, and humidity, so the bathroom is probably not the ideal choice!

Pick a closet or shelf elsewhere in the house that’s dark and doesn’t overheat. Reconsider if you’re keeping them in the kitchen, another notoriously steamy location.