How should you wash your face? Soap or cleanser, do you need it in the morning too, and when does double cleansing make sense.
Face washing is the simplest step in a routine, yet there's a lot of confusion around it: soap or cleanser, do you need it in the morning too, and what's double cleansing good for. I've written up what's actually been measured on this, and where I couldn't find a study, I say so and rely on the mechanism alone.
Why does it matter what you wash your face with?
I'm a cosmetology student, and I wrote this article because most places only say "twice a day" about face washing, without explaining what makes a cleanser good or bad, or how much of that is actually measured. Cleansers fall into two broad groups by their effect on skin: soap-based products and syndets (synthetic detergents, "syndet" for short). Oliveira and colleagues measured the pH of 96 cleansers sold in Brazil for children and sensitive skin in 2025 (34 bar soaps, 62 liquid ones, 20 of the latter being syndets). pH shows how acidic or alkaline a substance is: the higher it is, the more alkaline. The main finding: bar soaps were the most alkaline, averaging pH 10.25, while syndets were the lowest, averaging 6.00, closer to skin's physiological pH of 5.0-5.5. The detail: all products' pH ranged from 4.54 to 11.01, averaging 7.80; bar soaps ranged from 8.01 to 11.01, liquid soaps from 4.54 to 8.08 (average 6.50), syndets from 4.99 to 7.78.1
This figure on its own is a market survey, it doesn't measure what happens on your skin. But a review describes what follows from it. According to Mijaljica and colleagues' 2022 paper, syndets can preserve the skin's structure, function and integrity, while soap-based cleansers tend to damage the skin barrier: they strip lipids (the skin's own fat layer) and shift its pH. The same review also states that even the milder syndets can strip some of the skin's own components, and can cause some barrier weakening and irritation.2 Another, 2025 review, looking at the structure of surfactants (detergent-acting substances), writes that among negatively charged (anionic) surfactants, sodium lauryl sulfate (SLS) and the LAS type are strongly irritating, while double-charged (amphoteric) and uncharged (nonionic) types are better tolerated by skin. The difference comes from the molecule's structure: the charge on its water-loving "head", the size of the tiny spheres it forms in water (micelles), and the degree of ethoxylation, meaning how many ethylene oxide units are attached to the molecule.3
What you can take from this: if a cleanser is a bar soap, it's likely more alkaline and dissolves the skin's fat layer more strongly than a syndet-based face wash; products marketed as liquid "soap" have a lower pH than bar soaps (average 6.50), but syndets measure even lower still (average 6.00), and according to the study's authors, packaging rarely gives reliable information about pH anyway.
Average pH across 96 cleansers marketed for children and sensitive skin. The skin's physiological pH is around 5.0-5.5.
If cleansing, moisturizing and daily sunscreen are already covered, an LED mask can be considered as a cosmetic add-on.
See the LED mask
Why can a more alkaline, “natural” soap be worse for your skin?
The "natural equals gentler" association flips on its head with soap specifically. According to Mijaljica and colleagues' review, many people may choose soap because whatever doesn't feel "natural" easily gets a negative connotation, even though the review shows syndet as the gentler option.2 The same review, based on a cited study, also describes lecithin (a plant-derived cleansing substance counted as a biosurfactant) as having a much smaller barrier-damaging effect than "harsh", traditional anionic surfactants like SLS or SDS; this claim rests on a source cited within the review, I couldn't find the original measurement, so I'm only describing the direction, without a percentage.2
My own reading (not a single study's direct measurement): the review on surfactants states that SLS- and LAS-type anionic surfactants are strongly irritating3, but not every anionic surfactant is the same; the Mijaljica review cited above describes sodium cocoyl isethionate and potassium cocoyl glycinate (both anionic) as specifically mild, and a cited microscopy study found that nonionic-based cleansers altered the skin's lipid layer more than a mild, isethionate-based cleanser.2 On sensitive, newborn or atopic (eczema-prone) skin, then, the specific surfactant matters: SLS/LAS-type anionic surfactants are worth avoiding, while mild anionic (isethionate, glycinate) and amphoteric surfactants seem like good choices; the review on surfactants names this heightened sensitivity specifically for newborn and atopic skin, we don't have a direct source for dry skin.3
What you can take from this: on sensitive or atopic (eczema-prone) skin, the specific surfactant matters; this source doesn't speak to other skin types.
Do you have to wash your face in the morning too?
I couldn't find a direct study on this question. The case for morning washing is mechanism-level: overnight, the sebaceous glands keep producing sebum, dead skin cells build up on the surface, and your face spends hours in contact with your pillowcase too. This is basic skin physiology, but I can't give you a specific amount (how many micrograms of sebum build up in one night).
If your skin was already clean at the end of your evening routine and you didn't sweat much, a water rinse in the morning is likely enough; if your skin is oilier or you use an active ingredient in the evening, a cleanser wash in the morning makes more sense. I didn't find a study on this trade-off, it's a practical question you can decide based on your skin type and routine, not a scientific one.
What you can take from this: I didn't find research that settles the "do I have to wash in the morning" question; the mechanism (overnight sebum and cell buildup) justifies one cleanse, the form (water or cleanser) is up to you.
Do you need double cleansing if you wear sunscreen or makeup?
Double cleansing (an oil-based cleanser first, then a water-based one) rests on a simple chemical principle: oil dissolves oil-based residue better than water does. Many sunscreens and makeup products have an oil base, so an oil-based cleanser may dissolve them more effectively than a water-based facial wash on its own. This is a logical conclusion from how surfactants work, not the result of a clinical trial: I found no study measuring the benefit of double cleansing (whether it cleans better), nor whether it irritates more or clogs pores more.
If you don't wear makeup or a heavy sunscreen, a single cleanser suited to your skin type is probably enough; if you do, an extra step can logically help, but no source supports an “everyone, every day” claim for this step.
What to take from this: double cleansing is a reasonable but unmeasured step; it makes sense under heavy sunscreen or makeup, there's no evidence it's needed by everyone, every day.
Is micellar water enough on its own?
Micellar water dissolves surfactant molecules in water, which form tiny spheres (micelles) that attract oily residue to themselves. This is the chemical principle behind the technology, not a measured clinical effect: I didn't find a clinical comparison testing micellar water as a standalone, wash-replacing method. Many manufacturers recommend rinsing it off with water afterwards unless the product is specifically labelled "no-rinse", because residue and cleansing molecules left on the surface can stay on the skin; I didn't find a precise source for this, so I'm writing it as a practical recommendation. My own reading is that a quick rinse is a cheap safeguard against leaving lifted residue on the skin.
What you can take from this: micellar water can be a quick, practical step (travel, removing makeup), but I didn't find a clinical study on either its sufficiency on its own or the need to rinse afterwards, only practical recommendations.
Does hard water harm your skin?
These are two separate questions: does hard water cause harm, and does a water softener help once eczema is already present. Observational studies (which show things occurring together, not cause and effect) find an association between living with hard water and childhood eczema. A meta-analysis (an analysis pooling data from several studies) of 16 studies pooled the data of 385,901 participants across seven observational studies, and found higher odds of eczema in children living with hard water than those living with soft water. The quality of the data was rated "very low certainty", though.4 A smaller, 80-person study also found a mechanism: participants' skin was washed with a sodium lauryl sulfate solution, in water of varying hardness, and considerably more sulfate deposit remained on the skin washed in hard water. This caused more water to evaporate through the skin, and irritation was stronger, especially in those eczema patients carrying a mutation in the filaggrin gene (one of the skin's protective-layer building proteins).5
A water softener as a treatment is a different question, though, and the 336-child SWET trial found no benefit for it. Thomas and colleagues' 2011 SWET trial recruited 336 children aged 6 months to 16 years with moderate or severe eczema, at multiple centres in hard-water areas, meaning they already had eczema, and randomised them into two groups: one group had an ion-exchange water softener installed at home alongside usual care, the other received usual care only. After 12 weeks, the SASSAD scale measuring eczema severity improved by an average of 5.0 points (20 percent) in the water-softener group, and by 5.7 points (22 percent) in the usual-care group; the difference between the two groups (0.66 points) wasn't statistically detectable, meaning chance could explain it. The authors' conclusion, in their own words: the water softener provided no additional benefit over usual care alone in this trial population.6
The two pictures together: there's an observational association between hard water and childhood eczema (with very low certainty), but once eczema has already developed, installing a water softener didn't improve it more than usual care alone in this trial.
What you can take from this: there's an observational signal linking hard water and skin, but as a treatment for existing eczema, the SWET trial found the water softener didn't help more than usual care alone.
According to one review, lower-pH, syndet-based cleansers are gentler on the skin barrier than soap-based ones; morning washing and double cleansing are reasonable but unmeasured steps; hard water shows an observational association with childhood eczema, but a water softener as a treatment wasn't confirmed by the SWET trial, which included 336 children. For persistent irritation, itching or eczema, a dermatologist can help work out what's behind it.
How often a day should you wash your face?
A randomised trial (exclusively on men with mild-to-moderate acne, 6 weeks) compared washing once, twice and four times a day: the difference between the groups wasn't statistically detectable (chance could explain it), but the twice-a-day group saw improvement in open comedones and non-inflammatory lesions, while the once-a-day group's condition worsened. In the authors' own words, there's "mild support" for washing twice daily with a gentle cleanser; they add that washing too often may be less harmful than previously thought.7 A 2005 review states that, overall, there's surprisingly little evidence on the role of face washing in acne treatment.8 The trial only speaks to acne-prone male skin, it can't be generalised to everyone.
What is micellar water?
A water-based solution in which surfactant molecules float, forming tiny spheres (micelles) in water; one end of each molecule binds to oily residue, the other to water, dissolving away makeup or sebum. I found no clinical trial on micellar water as a standalone method; the description rests on the chemical principle behind the technology.
Why do you need to rinse off micellar water?
Unless the product is specifically labelled “no-rinse,” many manufacturers recommend rinsing it off, because the surfactant molecule and the residue it picked up can remain on the skin; I haven't looked into this in detail. I found no clinical trial on this, it's a practical recommendation, not a measured health claim.
Should you wash your face with soap or a facial cleanser?
A study measuring 96 products found bar soaps to have a more alkaline average pH (10.25, range 8.01-11.01) than syndets (6.00, range 4.99-7.78), which is closer to the skin's physiological pH of 5.0-5.5.1 One review states that soap-based cleansers damage the skin barrier more than syndets.2 Based on this, a syndet-based facial cleanser is more likely to be gentler, but individual skin tolerance can vary.
Which cleanser suits oily skin, which suits dry skin?
The specific surfactant matters, not just whether it's anionic. According to the source, SLS and LAS-type anionic surfactants are strongly irritating, and one review explicitly names this heightened sensitivity for newborn and atopic (eczema-prone) skin.3 Another review, however, describes other anionic surfactants (sodium cocoyl isethionate, potassium cocoyl glycinate) as mild, and found that a nonionic-based cleanser can alter the lipid layer more than a mild, isethionate-based one.2 For skin like this, an SLS/LAS-free, mild (isethionate-, glycinate- or betaine-based) syndet is the more reasonable choice. For dry or oily/normal skin, we have no direct source on which surfactant type is better tolerated; this is our own conclusion, not a claim made by the reviews cited.
Do you need double cleansing if you don't wear makeup?
The principle behind double cleansing is that an oil-based cleanser dissolves oily residue (sunscreen, makeup) better than water alone. If you don't wear heavy sunscreen or makeup, a single facial cleanser suited to your skin type is probably enough. I found no clinical trial on the benefit of double cleansing; this is a logical conclusion, not measured data.
Does hard water harm my skin, do I need a water softener?
A meta-analysis of 16 studies, pooling data from seven observational studies (385,901 participants), found higher odds of childhood eczema in those living with hard water, with very low certainty.4 If your child already has eczema, and you want to help with that: the SWET trial (336 children with eczema, aged 6 months to 16 years, 12 weeks) found no detectable difference between the group that got a water softener AND usual care, versus the group that got usual care only (improvement was 20 and 22 percent respectively).6 So there may be a link between hard water and eczema, but installing a water softener on existing eczema didn't help more than usual care alone in this trial.
Can I use an oil-based cleanser if I have oily skin?
I found no study specifically targeting this. Oil-based cleansers became popular as the first step of double cleansing, on the principle that oil dissolves oily residue, followed by a water-based facial cleanser suited to your skin type. For oily skin, the choice of the second, water-based step (a lower-pH syndet) is probably more important than the choice of the first, oil-based step.
Is it bad to wash my face with baking soda?
A baking soda solution in water is mildly to moderately alkaline (a well-known chemical fact, not from the skin studies cited here); this is a more alkaline, less physiological range than the skin's pH of 5.0-5.5. None of our sources recommend it as a facial cleanser, and I found no study measuring direct harm from it; based on its alkalinity alone, there's at least no reason to assume it would be gentler than a syndet-based facial cleanser.
Is SLS in facial cleansers carcinogenic or dangerous?
In the reviews cited (for one of them I only saw the abstract, the full text is paywalled), I found no section on carcinogenicity; what they describe is the irritating effect of SLS (sodium lauryl sulfate).3 Skin irritation and carcinogenicity are two separate questions, and they shouldn't be conflated. If your skin is sensitive, the fact of irritation alone is reason enough to choose a gentler facial cleanser free of SLS, built on a mild surfactant (for example isethionate-, glycinate- or betaine-based).
Where does face washing fit into your daily routine?
The first step of the minimum routine: cleansing, then moisturising, then sunscreen during the day. I wrote about the full routine here. This article expands on the cleansing step; you can read about moisturising and sunscreen in separate articles.
If cleansing, moisturizing and daily sunscreen are already covered, an LED mask can be considered as a cosmetic add-on. It does not replace the basic routine: until that is in place, your money is probably better spent on sunscreen.
See the LED mask
Sources
The studies cited include a market survey, reviews, a meta-analysis, two randomised trials (one in children with eczema, one in men with acne) and one mechanism study; none is about our own product.
- Oliveira RM et al. Children's soap pH analysis and its meaning in children's skin cleansing. Rev Paul Pediatr, 2025. PMID 41417527.
- Mijaljica D et al. Skin Cleansing without or with Compromise: Soaps and Syndets. Molecules, 2022. PMID 35335373.
- Abdollahi H et al. Surfactant-containing detergents: Impacts on dermal health. Colloids Surf B Biointerfaces, 2025. PMID 40795538.
- Jabbar-Lopez ZK et al. The Effect of Water Hardness on Atopic Eczema, Skin Barrier Function: A Systematic Review, Meta-Analysis. Clin Exp Allergy, 2021. PMID 33259122.
- Danby SG et al. The Effect of Water Hardness on Surfactant Deposition after Washing and Subsequent Skin Irritation in Atopic Dermatitis Patients and Healthy Control Subjects. J Invest Dermatol, 2018. PMID 28927888.
- Thomas KS et al. A randomised controlled trial of ion-exchange water softeners for the treatment of eczema in children. PLoS Med, 2011. PMID 21358807.
- Choi JM, Lew VK, Kimball AB. A single-blinded, randomized, controlled clinical trial evaluating the effect of face washing on acne vulgaris. Pediatr Dermatol, 2006. PMID 17014635.
- Magin P et al. A systematic review of the evidence for 'myths and misconceptions' in acne management: diet, face-washing and sunlight. Fam Pract, 2005. PMID 15644386.