You wouldn't drink from the same coffee cup for six months without washing it. But the mascara wand you've been using since spring? It's been swimming in a damp, dark tube, picking up a little something new every time it touches your lashes — then going back in.
And the science is unflattering.
"Microbial growth was found in 36.4% of mascara tubes cultured after 3 months of daily use. We recommend a maximum 3-month use of a mascara tube used on a daily basis." — Wilson et al., Optometry (2008) — peer-reviewed study, Reference [1]
Why mascara is a uniquely bad offender
Mascara is the perfect storm of beauty-product biology:
• It's wet. Liquid formulas give bacteria a place to grow.
• It's warm. Tossed in a bag, left in a bathroom, kept near body heat.
• It's sealed and dark. No light, no airflow — exactly what microbes love.
• It touches your eye. Every application reintroduces bacteria from your lashes, fingers, and the air.
Multiple studies have documented this. The most-cited (Wilson et al., 2008) found Staphylococcus epidermidis, Streptococcus species, and fungi in over a third of tubes after just three months [1]. A 2024 study on waterproof vs. non-waterproof formulas found Staphylococcus aureus in 33% of non-waterproof users' tubes after only two months of daily use [2]. Older clinical reports have documented even higher rates depending on conditions [3].
What can actually go wrong
Old mascara doesn't usually announce itself. It rarely smells. It usually looks fine. But ophthalmologists report a steady stream of patients with:
• Styes (those painful red bumps on the eyelid)
• Conjunctivitis — pink eye, basically
• Chronic eye irritation, redness, and itchiness
• Blepharitis (inflammation of the eyelid margins)
In most cases, patients have no idea their makeup is the cause. They'll change pillowcases, switch contact-lens solution, try eye drops — and never think to check the mascara tube they've been using since their birthday last year.
The three-month rule (and why no one follows it)
The American Academy of Ophthalmology is direct on this point: "Eye makeup should be thrown away three months after it is purchased but immediately if you develop an eye infection when you are using it" [4]. Mascara manufacturers often print the same number on the packaging — a small open-jar icon with "3M" inside, indicating three months from opening (the PAO, or Period After Opening symbol) [5].
The problem? Nobody remembers when they opened a tube. We open them, toss the box, and lose track. By the time you're scraping the bottom of a mascara, it's usually been six to twelve months — well past safe use.
What to do tonight
You don't need to throw everything out and start over. Try this instead:
• Audit your eye products first. Mascara, eyeliner, brow gel, eye cream, lash serum — anything that touches the eye area is highest risk.
• Open the tube. If the texture has changed, it smells off, or it's been more than three months — toss it.
• Mark new products as you open them. A pen on the bottom works. A dated sticker works better. This is exactly why we made EyeVida — but the principle matters whether you use our system or not.
• • •
EyeVida is a sticker system that takes five seconds: stick the month-marker on the day you open a product, replace when that month rolls around. Designed with input from eye-health professionals, made in the USA, and sized to fit mascara, liner, gloss, serum, and cream tubes.
References
1. Pack LD, Wickham MG, Enloe RA, Hill DN. "Microbial contamination associated with mascara use." Optometry. 2008 Oct;79(10):587-93. PubMed PMID: 18922495.
2. Shet RV, Mohammad N, Kurni E, et al. "Microbiological Contamination Linked to the Usage of Mascara among Waterproof and Non-Waterproof Brands and Tear Film Assessment." AJ J Med Sci. 2024;1(1):16–22.
3. Wilson LA, Ahearn DG. "Pseudomonas-induced corneal ulcers associated with contaminated eye mascaras." American Journal of Ophthalmology. 1977;84(1):112–119.
4. American Academy of Ophthalmology. "Eye Makeup Safety Tips." Available at: aao.org/eye-health/tips-prevention/eye-makeup-safety-tips
5. U.S. Food & Drug Administration / EU Cosmetics Regulation. Period After Opening (PAO) Symbol — open jar icon with months indicator.