skincare basics
How many times a day should you wash your face?
The one randomised trial comparing washing once, twice and four times a day found no difference. What did change outcomes was the cleanser and the water temperature.
No study has ever established a right number of washes per day. The one randomised trial that compared washing once, twice and four times a day found no meaningful difference between them (Choi et al., 2006). What did separate the outcomes was something else: which cleanser, and how hot the water.
Has anyone actually compared washing frequency?
One trial has compared washing frequencies directly, and its result was not what most people expect. Participants with acne were assigned to wash once, twice or four times daily and followed for six weeks. There was no statistically significant difference between the three groups (Choi et al., 2006).
The changes within each washing group ran opposite to the folk wisdom. The arm that got worse was not the one washing most, but the one washing least: redness and papules rose in the once-daily group. The authors wrote that excessive washing may not be as culpable as previously thought.
These are observations within the washing groups, so they settle nothing on their own. They do mean there is no ground for assuming that washing less is automatically safer.
Which part of washing made a difference?
What separated the washing outcomes was the chemistry of the cleanser. Adolescents and young adults with early inflammatory acne washed morning and evening for three months with either a soap bar or an acidic synthetic-detergent bar. Papulopustules rose from 14.6 to 15.3 in the soap group and fell from 13.4 to 10.4 in the acidic group (Korting et al., 1995). One author works for the company that makes the acidic bar tested.
The irritation gap was wider still: 40.4% of the soap group reported irritation, against 1.8% of the acidic group. Same frequency, same duration, different outcome.
The reason soap and the acidic bar diverged is usually sought in pH. Held in an alkaline environment, the stratum corneum's structural proteins swell and its lipid matrix stiffens (Ananthapadmanabhan et al., 2003). It is not washing that unsettles the barrier so much as what you wash with. Choosing by criteria is covered in how to choose a cleanser.
Does water temperature matter when washing?
Water temperature does matter. When 50 volunteers immersed their hands in 41 °C water for ten minutes, water loss more than doubled (25.75 → 58.58 g/h/m²) (Herrero-Fernandez et al., 2022). Surface pH rose with it.
In the same study, 11 °C water also raised water loss significantly, to 34.96. The idea that a cold rinse leaves the barrier better off is not supported by this data. Prolonged contact with water is the burden; hot is simply worse. What that measure means is in what TEWL is.
The caveat is real: ten minutes of immersion is not a thirty-second wash. Read the result for direction, not for magnitude.
Does washing reduce how much oil you make?
Surface oil drops, and not for long. When sebum was stripped from the forehead and nose and then tracked, surface levels were back at their own baseline within two hours (Rode et al., 2000). The time was the same whether the skin ran oily or not.
The opposite folk claim is no better supported. No primary study showing that frequent washing drives a rebound in oil production turned up. On this evidence the more accurate position is that washing returns oil to baseline rather than driving it above.
In short: washing is about how hard, not how often
While the question was how many times, what actually separated the outcomes was which product and how hot the water. The firmest evidence sits with the cleanser.
What there is to pare back is not how often you wash but how hard. Twice a day with a gentle product, kept short, is easier on skin than once a day with soap and hot water. Oil cleansing and double cleansing on heavy days continue in does oil cleansing actually remove blackheads.
One step today
- Move the tap one notch cooler and keep this week's washes lukewarm.
- Check whether your cleanser states a pH. If it doesn't, try one labelled mildly acidic next time you buy.
- Shorten how long lather sits on the face. What was measured is a ten-minute immersion rather than a thirty-second wash, but the direction is that less contact is better.
FAQ
References
- Choi, J. M., Lew, V. K., & Kimball, A. B. (2006). "A Single-Blinded, Randomized, Controlled Clinical Trial Evaluating the Effect of Face Washing on Acne Vulgaris." Pediatric Dermatology, 23(5), 421–427.
- Korting, H. C., Braun-Falco, O., Ponce-Pöschl, E., Klövekorn, W., Schmötzer, G., & Arens-Corell, M. (1995). "The influence of the regular use of a soap or an acidic syndet bar on pre-acne." Infection, 23(2), 89–93.
- Ananthapadmanabhan, K. P., Lips, A., Vincent, C., Meyer, F., Caso, S., Johnson, A., Subramanyan, K., Vethamuthu, M., Rattinger, G., & Moore, D. J. (2003). "pH-induced alterations in stratum corneum properties." International Journal of Cosmetic Science, 25(3), 103–112.
- Herrero-Fernandez, M., Montero-Vilchez, T., Diaz-Calvillo, P., Romera-Vilchez, M., Buendia-Eisman, A., & Arias-Santiago, S. (2022). "Impact of Water Exposure and Temperature Changes on Skin Barrier Function." Journal of Clinical Medicine, 11(2), 298.
- Rode, B., Ivens, U., & Serup, J. (2000). "Degreasing method for the seborrheic areas with respect to regaining sebum excretion rate to casual level." Skin Research and Technology, 6(2), 92–97.
- Takagi, Y., Kaneda, K., Miyaki, M., Matsuo, K., Kawada, H., & Hosokawa, H. (2015). "The long-term use of soap does not affect the pH-maintenance mechanism of human skin." Skin Research and Technology, 21(2), 144–148.
This article is for general information only and does not replace medical diagnosis or treatment.
