Dr. Bronner’s is not an ideal choice for eczema-prone skin. While it’s made from simple, recognizable ingredients and is free of synthetic additives, its high pH and strong cleansing action can strip the skin barrier in ways that worsen eczema. That said, some people with mild eczema do use it successfully with heavy dilution and careful technique.
The pH Problem
Healthy skin sits at a pH of about 5.0 to 5.5, which is mildly acidic. This “acid mantle” protects against bacteria, locks in moisture, and keeps the skin barrier functioning properly. In eczema, skin pH is already shifted toward alkaline, which contributes to barrier dysfunction. Dr. Bronner’s Pure-Castile Liquid Soap has a pH of 8.7 to 9.9, pushing skin even further from its natural range.
When the outer layer of skin becomes more alkaline, two things happen simultaneously: enzymes that break down skin proteins become more active, and enzymes that produce the protective fats between skin cells become less active. The result is a thinner, leakier barrier that loses water faster and lets irritants penetrate deeper. For someone whose skin barrier is already compromised by eczema, this can trigger or prolong flare-ups.
How Castile Soap Affects the Skin Barrier
All soaps and detergents, whether natural or synthetic, work by dissolving fats. That’s how they remove dirt and oil. The problem for eczema-prone skin is that the same fat-dissolving action also strips the protective lipid layers between skin cells. These layers are made of ceramides, cholesterol, and fatty acids, and they’re what keep moisture in and irritants out.
When those lipids are removed, water escapes through the skin faster (a process called transepidermal water loss), causing dryness, tightness, and scaling. Worse, water-soluble irritants can now penetrate deeper into the skin, triggering inflammation. This mechanism is directly involved in eczema flares. It’s not unique to Dr. Bronner’s. Traditional soaps, synthetic detergents, shampoos, and even emulsifiers in some lotions all contain surface-active ingredients that can damage these lipid layers.
Dr. Bronner’s does retain naturally occurring glycerin from the saponification process, which has some moisturizing benefit. The bar soap versions also contain unsaponified oils (“superfatting”) that leave a small amount of oil on the skin. But these features don’t fully offset the stripping effect, especially on eczema-prone skin that’s already struggling to maintain its barrier.
What’s in the Unscented Version
The Baby Unscented variety is the safest Dr. Bronner’s option for sensitive skin. Its ingredient list is short: water, organic coconut oil, potassium hydroxide (which is fully consumed during soap-making), organic palm kernel oil, organic olive oil, organic hemp seed oil, organic jojoba wax, citric acid, and tocopherol (vitamin E). No fragrances, no preservatives, no synthetic surfactants.
None of these ingredients are common eczema triggers on their own. The citric acid helps lower the pH slightly, and the jojoba and hemp oils add some skin-conditioning properties. If you’re going to use any Dr. Bronner’s product on eczema-prone skin, this is the one to choose.
Why Scented Varieties Are Riskier
Dr. Bronner’s scented soaps contain essential oils like peppermint, tea tree, eucalyptus, and lavender. Essential oils are a well-known source of contact dermatitis, particularly on damaged skin. Peppermint oil contains menthol, which creates a cooling sensation that can feel soothing but actually irritates compromised skin. Tea tree oil is a frequent cause of allergic contact reactions.
Lavender oil is an interesting case. Lab research has found that lavender essential oil and its main components can actually suppress some of the cellular processes involved in eczema, with minimal skin sensitization potential. But lab findings don’t always translate to real-world use on broken, inflamed skin. If your eczema is active, essential oils of any kind introduce unnecessary risk.
If You Still Want to Use It
Some people with eczema-prone skin tolerate Dr. Bronner’s well, particularly if their eczema is mild or in remission. The key is dilution. The soap is highly concentrated, and using too much is the most common mistake. For a full body wash, 4 to 5 drops mixed with water is the recommended amount. For bathing babies, 4 drops in a full tub of warm water. You can also mix about 1.5 teaspoons into a cup of water for a diluted wash.
A few practical tips if you go this route:
- Use the Baby Unscented version to avoid essential oil irritation
- Dilute heavily and don’t apply the concentrate directly to skin
- Limit contact time by rinsing quickly rather than letting it sit
- Moisturize immediately after while skin is still damp, to seal in hydration before barrier disruption leads to water loss
- Avoid using it on active flares where the skin is cracked or weeping
What Works Better for Eczema
Dermatologists generally recommend soap-free cleansers (sometimes called syndets, short for synthetic detergents) for eczema. Despite the clinical-sounding name, these are widely available products like Cetaphil Gentle Skin Cleanser, CeraVe Hydrating Cleanser, and Dove Sensitive Skin bars. They’re formulated at a pH closer to 5.0 to 5.5, matching the skin’s natural acidity, and they clean without stripping lipids as aggressively as traditional soaps.
The tradeoff is that these products often contain synthetic ingredients that people who prefer Dr. Bronner’s are specifically trying to avoid. That’s a personal decision. But from a skin barrier standpoint, a pH-matched cleanser with ceramides or gentle surfactants will be kinder to eczema-prone skin than even the most carefully diluted castile soap. If your priority is managing eczema, a soap-free cleanser is the more effective tool. If your priority is using natural products and your eczema is mild, heavily diluted unscented Dr. Bronner’s is a reasonable compromise.