The best soap for eczema is technically not soap at all. Traditional bar soaps are alkaline and strip the skin’s protective barrier, making eczema worse. What dermatologists recommend instead are soap-free cleansers, often called syndets or soap substitutes, that clean without disrupting the skin’s natural defenses. The key features to look for: fragrance-free, low pH, and formulated with ingredients like ceramides, glycerin, or petrolatum that help the skin hold onto moisture rather than lose it.
Why Regular Soap Makes Eczema Worse
Healthy skin sits at a slightly acidic pH. In people with eczema, skin pH already skews more alkaline than normal, which contributes to barrier dysfunction. Traditional soap, made by combining fats with lye, is highly alkaline. A 2024 study testing 37 bar soaps found every single one had a highly alkaline pH. Washing with them pushes already-compromised skin further in the wrong direction.
The damage goes deeper than pH alone. Surfactants in soap denature keratin, the structural protein in your outer skin layer. This initially causes the skin to absorb extra water, but once that water evaporates, the damaged keratin can no longer hold moisture the way it used to. The result is skin that feels tight, dry, and more prone to cracking and flaring. Surfactants also interfere with lipid-processing enzymes and can disrupt how new skin cells mature, compounding the barrier problems that define eczema.
What to Use Instead
Soap-free cleansers, called syndets (short for “synthetic detergent”), are formulated at a lower pH that’s closer to your skin’s natural range. In the same study that found all 37 bar soaps were highly alkaline, nearly 85% of liquid syndets tested were acidic, which is the desirable range for eczema-prone skin. Another 11% were neutral, which researchers considered acceptable. If a product is marketed as “pH balanced,” it’s almost certainly a syndet rather than a true soap.
Beyond pH, the best eczema cleansers include ingredients that actively support the skin barrier during washing. People with eczema tend to have decreased levels of ceramides in the outer skin layer. Ceramides are fatty molecules that form water-regulating structures between skin cells, essentially acting as the mortar between bricks. A randomized trial found that a ceramide-based cleanser and moisturizer system significantly improved both skin hydration and barrier function in adults with moderate eczema, while a placebo regimen either held steady or got worse.
Look for cleansers that combine three types of moisturizing ingredients: humectants like glycerin that pull water into the skin, occlusives like petrolatum or dimethicone that lock that water in, and emollients that smooth the rough, flaky texture eczema creates. Some products bundle all three into one formula, which means the cleanser itself is doing less damage and offering some repair during the wash.
Ingredients to Avoid
Fragrance is the single biggest ingredient to avoid. The National Eczema Association requires that any product carrying its Seal of Acceptance be fragrance-free, with no ingredient present solely to make the product smell good. But “fragrance” on a label can represent dozens of individual chemicals, any of which can trigger irritation or allergic reactions in sensitive skin.
Sodium lauryl sulfate (SLS) is the most studied irritant surfactant in dermatology. It raises the pH of the outer skin layer, denatures keratin, degrades lipid-processing enzymes, and impairs how skin cells develop. While the concentrations used in research studies (0.5% to 1%) are often higher than what appears in consumer products, SLS remains a reliable trigger for irritation. Checking ingredient lists for SLS and its close relative sodium laureth sulfate is a simple way to filter out harsher cleansers.
Dyes, essential oils, and botanical extracts can also irritate eczema-prone skin even when they sound natural or gentle. “Natural” does not mean non-irritating. A short ingredient list is generally a safer bet than a long one.
The “Fragrance-Free” Label Trap
There’s an important distinction between “fragrance-free” and “unscented” that catches many people. “Fragrance-free” generally means no fragrance was intentionally added to create a scent, but it doesn’t guarantee the product contains zero fragrance-related chemicals. Manufacturers sometimes use masking fragrances to cover the unpleasant smell of other ingredients, and these don’t have to be disclosed as “fragrance” on the label. They can still trigger reactions.
“Unscented” is even less reliable. It simply means the product has no noticeable smell, but it may contain fragrance chemicals specifically chosen to neutralize odors. For eczema-prone skin, “fragrance-free” is the better choice of the two, but neither label is a guarantee. Checking for the National Eczema Association’s Seal of Acceptance adds another layer of vetting, since those products must pass clinical safety testing on at least 100 participants, with at least half having sensitive skin.
How to Wash With Eczema
The cleanser you choose matters, but so does how you use it. Short daily baths or showers in lukewarm water are the standard recommendation. Hot water feels soothing in the moment but accelerates moisture loss and can trigger itching as your skin cools. There’s no precise evidence-based number for water temperature or bath duration, but most guidelines suggest keeping showers under 10 to 15 minutes.
Apply your cleanser only where you actually need it: underarms, groin, hands, feet, and any visibly dirty areas. Letting soapy water run over the rest of your body provides enough cleansing for most skin without the extra surfactant exposure. Pat dry with a towel rather than rubbing, and apply moisturizer within a few minutes while your skin is still slightly damp. This locks in the hydration your skin absorbed during the bath rather than letting it evaporate, which would leave your skin drier than before you washed.
How to Identify Trustworthy Products
The National Eczema Association’s Seal of Acceptance program is the most rigorous independent vetting system for eczema products. Beyond requiring fragrance-free formulations, the NEA maintains an “Ecz-clusion List” of banned ingredients. Manufacturers must submit not just an ingredient list but each ingredient’s function and the complete formula. Products also need clinical safety testing across diverse skin types, ages, and genders. The program does not accept animal testing.
If a product doesn’t carry the NEA seal, you can still evaluate it yourself. Flip to the ingredient list and check for: no fragrance or parfum, no SLS, no dyes. Look for ceramides, glycerin, petrolatum, or dimethicone near the top of the list. Choose liquid cleansers over bar soap when possible, since liquids are far more likely to have an appropriate pH. And when in doubt, a simpler formula with fewer ingredients gives your skin fewer opportunities to react.