How Often Should You Clean Makeup Brushes?

Makeup brushes and sponges genuinely do carry substantial bacterial and fungal loads. That part is measured and real.

Almost everything else you have been told about cleaning them — the interval, the don't-submerge rule, the never-dry-upright rule, the warning that dirty brushes cause infections — traces back to a single uncited page, or to something worse.

Where "every 7 to 10 days" actually comes from

We expected this number to be beauty-blog folklore. It is not. It is the American Academy of Dermatology's own, word for word:

"it's a good idea to wash your brushes every 7 to 10 days"

So the interval every beauty site repeats is attributable to a national dermatology body. The problem is one level up: that page carries no citation, no author, no references section and no review date, and the sentence has been sitting there unchanged since at least April 2020.

So: two authorities, two different intervals — 7–10 days and weekly — and neither has evidence behind it. The British Association of Dermatologists publishes nothing on the subject at all, and neither does the FDA, whose entire instruction on the topic is four words: "Keep containers and applicators clean."

A 2026 review in Frontiers in Microbiology says it plainly: "Across product categories, standardized cleaning guidance for home users remains fragmented and product-specific. No universal protocol exists."

That same review notes the American Dental Association does publish a toothbrush interval. So a professional body can anchor an interval for a grooming tool when the evidence supports it. For makeup brushes, none has.

What is solidly evidenced: the contamination

The best-known work here is a 2020 study in the Journal of Applied Microbiology that cultured used cosmetics donated by their owners:

"About 79–90% of all used products were contaminated with bacteria… Presence of Staphylococcus aureus, Escherichia coli and Citrobacter freundii was detected."

Bacterial loads ran to 10²–10³ CFU/ml for most products, and over 10⁶ CFU/ml for beauty blenders — the sponges being far worse than anything else. The behavioural finding is the memorable one: 93% of those sponges had never been cleaned, and 64% had been dropped on the floor and used anyway.

What is not evidenced: that this makes you ill

The AAD page states, uncited, that dirty brushes "can cause an infection, such as a fungal infection, E. coli, or a staph infection, which can be very serious."

We went looking for the cases. Every documented human infection traced to a cosmetic applicator in the literature we found is an eye infection from a mascara wand — and in each one the mechanism was corneal trauma. The wand scratched the eye, and contaminated product entered the wound. That is three papers spanning 1977 to 1990, and it is a real and serious phenomenon.

We found no case report, outbreak investigation or cohort study linking a face makeup brush to a diagnosed infection.

Contamination is demonstrated. Causation is not. Those are different claims and only one of them has evidence.

The technique rules trace to one paragraph

Both of the mechanical rules everyone repeats come from the same uncited AAD page:

"Only rinse the tip, as submerging the whole brush head will eventually dissolve the glue that connects the brush head to the handle."

"Do not dry your brushes upright in a container, as this will cause the water to run down the brushes, loosening the glue…"

Brush bristles genuinely are bonded inside the metal ferrule with adhesive — a patent application for an applicator brush describes them as "potted in epoxy". That confirms the construction and nothing else.

Nobody has tested whether water actually degrades that joint. We are not going to assert the mechanism and we are not going to debunk it. One observation, flagged as ours rather than sourced: cured epoxy is a thermoset and water does not dissolve it. Whatever happens at a wet adhesive joint over time is something slower and different. The word is wrong even if the advice is sensible.

What the advice is actually worth

The practical upshot is not "don't bother". Brushes demonstrably accumulate bacteria, cleaning them demonstrably reduces that, and washing them regularly costs you almost nothing. Do clean them.

What you should not do is treat 7 days as meaningfully different from 10, or 10 from 14, or believe that missing the window is putting your skin at a documented risk. Nobody has established that, and the bodies quoting numbers are not showing their work.

What we could not establish

• Any evidence base for any cleaning interval. Two authorities give two different numbers and neither cites anything.
• Whether water degrades ferrule adhesive, or whether drying position matters. Both trace to a single uncited paragraph.
• Whether contaminated face brushes cause skin infections. Contamination is measured; the causal link is asserted, not shown.
• The widely quoted salon-tool contamination percentages. They trace to a 2012 paper in a journal we could not retrieve, so we have not printed them.
• ISO 21322's scope. A review describes it as a manufacturer-testing standard rather than consumer guidance; ISO's own site refuses automated access, so we report that on the review's authority, not ISO's.
• Whether ultrasonic brush-cleaning devices work. The 2026 review states there is no peer-reviewed evidence for their antimicrobial efficacy in home settings.

Sources consulted, retrieved 28 July 2026:

• How to clean your makeup brushes — American Academy of Dermatology. Quoted for the interval and the two technique rules, and cited as the origin of all three.
• TFOS Lifestyle: Impact of cosmetics on the ocular surface. Ocul Surf 2023 — quoted for the weekly interval, and for its own reference [400], which we retrieved from its reference list.
• Bashir A, Lambert P. Microbiological study of used cosmetic products. J Appl Microbiol 2020;128(2):598–605. Note: this study tested sponges and product, not brushes.
• Attar RMS, Imam MA. Int J Microbiol 2025 — brush swabbing and the cleaning-frequency null result.
• Iskandar K, Marchin L, Roques C. Front Microbiol 2026 — absence of a consumer protocol, and the ADA contrast.
• Załęcki P, et al. J Cosmet Sci 2021 — the controlled comparison of cleaning agents.
• Wilson LA, Ahearn DG. Am J Ophthalmol 1977 and Reid FR, Wood TO. Arch Ophthalmol 1979 — mascara-applicator corneal ulcers.
• Microbiological Safety and Cosmetics and Eye Cosmetic Safety — US Food and Drug Administration.

GlowSteal has not tested any product for this article and names none. General information, not medical advice — an eye that is painful, red or light-sensitive after using a cosmetic is a same-day matter for a doctor, not something to read about.