If you wear makeup, you’ve probably held onto an eye shadow palette too long, tried to squeeze one more use out of a dried-out mascara tube, or pumped out liquid foundation that’s clearly separated. Is it really a big deal?

It can be. Makeup doesn’t typically come with an expiration date, but that doesn’t mean it lasts forever.

“Over time, bacteria, yeast, and mold can grow in cosmetics, especially products exposed to air, fingers, or the eye area,” says Anna Karp, DO, a board-certified dermatologist in private practice and clinical assistant professor at the NYU Grossman School of Medicine in New York City. The result can be anything from skin irritation and breakouts to eye infections.

Does Makeup Really Expire?

No U.S. laws require cosmetics manufacturers to put an expiration date on their product labels. The exception is products that contain SPF — these are regulated by the U.S. Food and Drug Administration as both cosmetics and drugs, and they have an expiration date to ensure efficacy.That said, makeup has a shelf life. “Most people keep makeup longer than recommended, especially products like mascara, liquid liner, and foundation. Unlike food, many cosmetics don’t have obvious spoilage signs, so it’s easy to assume they’re safe,” Dr. Karp says. That’s not the case — old makeup can pose health risks for your skin and eyes.

Health Risks of Using Expired Makeup

The main risks of using expired makeup are microbial contamination and ingredient degradation, says Karp. Over time, key ingredients break down, including SPF, preservatives that prevent bacterial growth, and emulsifiers that keep ingredients blended. As these ingredients lose their effectiveness, the product becomes less stable and potentially harmful to skin. “This can lead to irritation, allergic reactions, breakouts, or infection, depending on the product and where it’s used,” Karp says.

Skin Irritation and Allergic Reactions

The presence of bacteria in makeup can be harsh on skin, causing skin irritation and allergic reactions. This is especially common in people with eczema (a chronic inflammatory condition that causes dry, itchy skin), rosacea (a chronic skin condition causing redness and acnelike bumps), or sensitive skin. “These patients are more vulnerable because the skin barrier is already compromised,” Karp says. (The skin barrier is the protective outer layer of skin that keeps moisture in and harmful bacteria out.)

Possible symptoms include stinging and burning, contact dermatitis (an itchy rash caused by an irritant on the skin), and rosacea flare-ups. If you have sensitive skin, eczema, or rosacea, Karp recommends being even more vigilant about tossing old cosmetics.

Acne and Clogged Pores

Although some makeup may be designed to hide acne breakouts, it can also cause them. “Patients often notice stubborn or unusual breakouts when using old liquid or cream products,” Karp says. That’s partly because oils in makeup oxidize (become exposed to oxygen) over time, and oxidized oils are known to promote acne formation.Bacterial and mold buildup in older products can also contribute to clogged pores.

Eye and Lip Infections

Mascara is one of the riskiest makeup products when used after about three months, says Karp. That’s because it’s high in moisture, making it prone to microbial contamination, and the mascara wand makes repeated contact with the eyes.  Potential infections include conjunctivitis (pink eye), styes (painful bumps on the edge of the eyelid caused by bacteria), and blepharitis (chronic inflammation of the eyelid edges), says Karp.Mascara can also be contaminated with Staphylococcus aureus (Staph) bacteria, a leading cause of skin and eye infections.Lip products carry risks, too. The lips carry bacteria that can transfer to lipstick and lip gloss with each use. One particular concern is cold sores, which are contagious, fluid-filled blisters caused by the herpes virus. If you or someone else applies a lip product during an outbreak, the virus can linger on the product and cause reinfections. Experts recommend throwing away any lip products used during a cold sore flare.

How Long Does Makeup Last?

To give you an idea of when to toss your makeup, here’s how long common products typically last once opened.

How to Tell if Your Makeup Has Expired

It may seem wasteful to toss a lipstick you’ve only worn twice, but your skin’s safety should come first. Karp recommends replacing any makeup that shows these warning signs:

• Change in Smell The product smells off or rancid.

• Separation or Clumping The ingredients have visibly separated in the bottle, and you need to shake it to redistribute them.

• Change in Color Depending on the product, it might look discolored, such as yellowing, darkening, or becoming orange.

• Dried Out or Thickening Mascara or lip gloss is dry or comes out clumpy, making it difficult to apply smoothly or evenly.

• Irritation After Use You notice redness or stinging in the eye or lip area after applying the product.

However, just because a product doesn’t show signs that it’s expired doesn’t mean it’s safe to use. It’s best to follow the shelf life guidelines, even if the product looks and smells fine.

3 Tips for Extending Makeup's Shelf Life

Follow these tips to extend the shelf life of your products:

• Store makeup properly. Keep cosmetics out of extreme heat; don’t leave your makeup bag in a hot car, for example. Store them in a dry, clean area at room temperature.

• Keep your hands out. Using your fingertips to apply your makeup introduces germs into the product, increasing the risk of contamination. Instead, use brushes, sponges, and other applicators, and clean them with shampoo at least once per week.

• Don’t share. Sharing makeup can expose you to someone else’s bacteria or infection. It’s also best to avoid testing products at store cosmetic counters, where samples may be contaminated by multiple users.

The Takeaway

• Most cosmetics aren’t required to include an expiration date. The exception is products that contain SPF.

• Over time, cosmetics can become contaminated with bacteria and mold, and their ingredients can break down, altering their texture and color and posing risks to skin and eyes.

• The health risks of using expired makeup include eye infections, skin irritation, and acne.

• Follow the recommended guidelines for replacing makeup. But if you notice a change in color, texture, consistency, or smell — or experience irritation or infection after use — toss it right away.