Makeup and skincare products aren’t cheap, so it’s understandable to want to use every last bit before paying up for a replacement. But continuing to use items past their prime might cost you in other ways. It’s true: most makeup items actually need to be cleaned or replaced—and probably more frequently than you think.

This is because nine out of 10 makeup products are contaminated with bacteria, including heavy hitters like E. coli and Staphylococcus, according to a February 2020 study in the Journal of Applied Microbiology¹. “At least a couple of times a year, I will see patients coming in with a flare in their acne or styes and conjunctivitis that we can link directly back to a makeup product,” says Noreen Galaria, MD, a Washington, D.C. board-certified dermatologist and founder of Inner Glow Vitamins.

When exactly you should change out a product varies. That’s because certain items tend to turn into germ pits faster than others. Here, derms share their dirtiest offenders and when it’s time to re-up on your faves.

8 makeup items to clean or replace

Here are the top products that you might want to consider tossing or replacing.

1. Makeup brushes

When to clean: Once a week

Your makeup brushes pick up residue, oils, dead skin cells, and bacteria each time they touch your face. “This buildup can cause breakouts and skin irritation,” says Blair Murphy-Rose, MD, a board-certified dermatologist in Newport Beach, California, New York City, and founder of Skincare Junkie. You should dip them in warm, sudsy water (a mild dish soap or sulfate-free shampoo will do the trick) and let them air dry once a week.

In between cleanings, consider spraying the tip of the brush with 70 percent isopropyl alcohol to help get rid of surface bacteria. “This is a great tip if you’ve had to share your brush, have been sick, or had a recent acne breakout, especially if you don’t want to transfer bacteria to your face but don’t have time for lengthy cleaning,” Dr. Galaria says.

If the bristles are starting to fall out or fray, it may be time for a replacement. We like the Laura Geller Full Face Professional Makeup Brush Set ($39, Amazon). The brushes are professional-grade, vegan, and come in a variety of sizes.

2. Beauty blenders and makeup sponges

When to clean: Two weeks for reusable products

When to replace: After each use for non-reusable products

Beauty blenders and any makeup application tool with a spongy texture can pick up bacteria from your skin and spread it all around, upping the odds for breakouts and irritation. If a blender or makeup sponge is meant to be disposable, “they should be thrown out after every use,” Dr. Galaria says.

As for reusable ones? These are typically made from antimicrobial materials, “so they can be used for two weeks and then washed along with your makeup brushes,” she adds.

We like the Koh Gen Do Makeup Sponge ($30 for 2-pack, Amazon) for foundation and the Original Beautyblender Makeup Sponge ($20, Sephora) for mature skin.

3. Mascara

When to replace: Every three months

It often feels like you can hold onto mascara forever because there’s always plenty of product left in the tube. But it’s best to swap tubes out once a season, even if the Period After Opening (PAO) symbol indicates a longer shelf life. That’s because mascara is applied close to your eyelash line, where tons of bacteria like to hang out. That bacteria then go back into the tube, where it happily thrives until you take the applicator out next time and put it back onto your eyes, explains Dr. Galaria.

If you’re in the market for a new mascara, we love Charlotte Tilbury’s Pillow Talk Push-Up Lashes Mascara ($29, Nordstrom).

4. Liquid, cream, and gel eyeliners

When to replace: Every three months

Any other moisture-rich product that regularly goes near your eyes should be replaced alongside your mascara, says Dr. Murphy-Rose. “Pencil liners can last longer if they are regularly sharpened to a new point and the tip is wiped with alcohol to sterilize,” she adds.

We like Stila’s new Stroke of Genius Eye Duo gel eyeliners ($28, Amazon) or e.l.f. Satin Eyeliner Pencil ($3, Amazon) if you’re looking for new options.

5. Micellar water

When to replace: Every six months

These cleansers gently remove dirt and grime, but because they have such a high water content, they can eventually start to harbor bacteria and mold themselves, Dr. Galaria says. Storing micellar water in a cool, dark place can help prolong its shelf life, but after the half-year mark, it has to go. You should also replace it sooner if you spot any mold, which usually appears as a cloudy film or blue-green bits around the surface of the water, she adds.

One of our faves is Garnier SkinActive Micellar Cleansing Water. The brand recently launched a travel-size holiday kit ($12, Ulta) with three different types of cleansers.

6. Lip balm, cream blush, and face cream in jars

When to replace: Every six to 12 months

Any jarred product that requires you to open the lid and use your fingers to scoop the product out can turn into a germ pot pretty quickly. “There’s an increased risk of contamination [compared to pump or tube-dispensed products] because they are exposed to air and microorganisms each time they are opened,” Dr. Murphy-Rose says. To keep the germs to a minimum, consider using a disposable or washable applicator instead of your fingers and giving the jar rim and lid weekly wipe-downs with rubbing alcohol, she adds.

One of our favorite lip balms is the Laneige Lip Sleeping Mask ($24, Sephora). We also like Rhode Pocket Blush ($24, Rhode) and Honest Beauty Ageless Firm+Smooth Cream ($30, Amazon).

7. Liquid foundation

When to replace: Every 12 months

Aside from the fact that older products tend to harbor bacteria, “they can oxidize over time, changing in consistency, color, or smell,” Dr. Murphy-Rose says. To keep track of when it’s time for a new one, write down the date when you opened your foundation on the jar with a permanent marker. Toss it sooner if it shows any signs of texture change, discoloration, or foul smell.

We know there are a lot of foundation brands out there to choose from. One that’s stood out to us recently is the Huda Beauty Easy Blur Airbrush Foundation ($37, Sephora).

8. Lipstick

When to replace: Every 12 months

Once you fall in love with a certain lipstick, it can be hard to kiss it goodbye (pun intended) after a year or so. But “lipstick can collect bacteria from the lips and mouth, which increases the risk of infections,” Dr. Murphy-Rose says. This is why it’s important to replace them after a while.

Also, if you want to keep germs at bay, consider sterilizing your lipsticks every other week or so, as Dr. Murphy-Rose recommends. Just submerge the tip in rubbing alcohol for a few seconds and gently wipe it with a tissue.

Ready to try something new? Our recent lipstick favorites include Merit Signature Lip Lightweight Lipstick ($26, Sephora) and Dolce & Gabbana Beauty Gemstone Lipstick ($53, Nordstrom) if you want to splurge.