You may have run out of mascara right before a night out, dug into the depths of your drawer, found one from a few lifetimes ago, and endured the clumpy or dried-out consistency in desperation. But old cosmetics can come with much more risk than just reduced quality and performance—they can damage your skin and eyes.

Although there may be a date on your mascara tube, neither the US Food and Drug Administration nor federal law requires expiration dates for cosmetics. There are also no rules that set specific shelf lives for these products. Exceptions include sunscreen and acne products, which the FDA considers drugs, and any personal care products with an SPF rating, which are regulated as both cosmetics and drugs. Many manufacturers, however, provide a “period after opening” (PAO) date as part of their standard business practices, says Suzanne Friedler, a dermatologist at Advanced Dermatology PC. This leaves risk assessment to consumers.

“[Products] are going to be more dangerous if you have sensitive skin, and they are going to be more dangerous if you’re using it in a sensitive skin area like your eyelids, which are very thin skin,” Friedler says. When you’re trying to tell if a product has gone bad, Friedler recommends you use all your senses, especially if you can’t find a PAO date. “It’s not just following the date, it’s following your judgment,” she says. “Follow your instincts.”

Liquid eye makeup is the most dangerous of them all

Before you try to avoid the last-minute scramble by buying the most massive tub of liquid eyeliner or mascara you can find, consider how much bacteria loves dark, wet environments. This fact, coupled with the products’ proximity to your eyes, makes liquid-based eye cosmetics the most problematic.

Even if you think you are much cleaner than the average makeup user, you might be surprised at what’s lurking so close to your eyes. A study published in the Journal of Applied Microbiology in 2019 found that 79 to 90 percent of all the used products the researchers examined—including lipstick, lip gloss, eyeliners, mascaras, and beauty blenders—had grown “significant levels” of bacteria and other microbial contaminants.

“Mascara and eyeliner are most harmful to the eyes when they are expired because they come in close contact with the ocular globe,” says Monica Hazien, an optometrist for Now Optics, parent company of My Eyelab and Stanton Optical. “Upon contact with the eye, they can introduce bacteria and fungi directly to the ocular surface and open the door for a possible eye infection.” This can lead to eyelid irritation and bumps, acne, eyelid dermatitis, eye redness, foreign body sensation, tearing, and dry eye symptoms—not the type of eye drama you were hoping for when you applied makeup. Some of the infections can even develop into conjunctivitis (pink eye) and blepharitis from old makeup, she says.

[Related: How to prevent eye strain when you stare at screens all day]

No need to remember dates, unless you have a product with a PAO, Hazien says. Instead, simply throw out the mascara when the wand dries out or begins to flake (those flakes can also get into your eyes and cause irritation). “Expired eyeliner can change colors and may develop a funky odor,” she adds. She also hopes consumers avoid “tightlining,” or the practice of putting liquid eyeliner on water lines at the edge of their eyelids, which blocks the oil-secreting Meibomian glands and can cause dry eye symptoms. 

Lotions, soaps, and creams: stretching the life of harmless products

If you come across a sealed petroleum jelly container, or even a bar of soap, you are much less likely to have health issues even if they were produced years ago, according to YouTuber and dermatologist Andrea Suarez, aka Dr. Dray. “As long as they are still in the packaging, unopened and unused, they are likely to be okay a bit beyond the expiration date, as they are waterless,” she says. However, she notes that cosmetics containing retinol or vitamin C are “relatively unstable” after they’ve been exposed to light and air. “Beyond the expiration date, these ingredients can lose potency and become more irritating to the skin,” she says. So, it’s likely you can use your favorite lotion after its expiration date without concern, unless it has those ingredients.

It’s a similar story with facial cleansers, which Suarez says typically last six months to a year once opened. The shelf life of creams and lotions, though, may vary and she recommends you check the packaging.

The exception: A warning about sunscreens

Sunscreens, meanwhile, should always be thrown out by the expiration date to prevent sunburn and sun damage stemming from ineffective protection, Suarez says. This also includes foundations that might include sunscreen. 

A manicure after the expiration date

Nail polish, even if it has separated, is one of the least harmful cosmetics to use after its expiration date, says Adrienne Kramer, a chemical engineer and CEO of beauty brand consultancy Pro Beauty Partners,. Two-phase products like this are meant to be shaken to become homogeneous, and if they separate, you probably won’t get the manicure you were hoping for, but it won’t hurt you, she explains.

“It’s unlikely that they would be unhealthy or dangerous, because there really aren’t ingredients formulated into skincare nowadays that would provide that outcome,” she says. “The color and coverage might not be consistent throughout, and so the desired benefits—long-lasting, chip-free, and great color and shine—are unlikely.”

The art of application: How you apply cosmetics matters

Makeup artists don’t put the applicator on someone’s eye or lip, then back into the container. Neither should you, Friedler says. Instead, invest in spatulas, wands, brushes, applicators, or cotton swabs as applicators so you aren’t contaminating your makeup and other products. She also recommends sharpening eye pencils after use, and cleaning wands thoroughly—especially if you’ve been sick or have a cold sore. 

Additional tips she recommends to prolong the use of your cosmetics and reduce the risk to your eyes and skin include:

  • Wash your brushes thoroughly with soap and warm water to keep them cleaner, and to help them last longer.
  • Make a note of the expiration date (in your calendar, or by writing directly on the product before you throw the box away).
  • Store products in a cool, dry, place, rather than in heat (makeup in your car, anyone?) or near the shower.
  • Use a travel-sized product that’s more likely to be used up by the time it goes bad.
  • Opt for powders over liquids whenever possible—they will gather less bacteria.
  • Choose items that have a pump, so you aren’t introducing any bacteria from your skin back into the container.
  • Purchase products in an opaque container, not a clear one, to slow breakdown from light.

Luckily, infections from expired products are relatively rare, Friedler says, so it’s not necessary to learn extensive rules pertaining to cosmetic expiration dates. Instead, use a little common sense. If your gut is telling you a product looks a little funky, keep it far away from your precious eyes, mouth, and skin. Your health depends on it.