Lye Soap: Old-Fashioned Cleansing for Sensitive Skin

Updated October 2026 · By Kerrieanne Lischka, founder and soapmaker at Ollie Skincare

At almost every market, someone picks up one of our bars, flips it over, reads "sodium hydroxide" on the label and sets it back down. Lye sounds scary. I get it. But every real bar of soap, including your grandmother's and mine, starts with lye. What matters is what's left when the soap is finished, and how gentle the bar is on your skin.

Here's what lye soap is, what it isn't, and how to choose a bar that's kind to sensitive skin, from someone who makes it in small batches in Wisconsin.

The short answer

• All true soap is made with lye. Fats and oils plus lye make soap. Without lye, you don't have soap; you have a detergent.
• No lye is left in a well-made, cured bar. It's used up in the reaction that turns oil into soap and glycerin.
• Soap is mildly alkaline, and that's normal. That's why the right recipe, a little extra oil, and good habits after washing matter for sensitive skin.
• For sensitive or reactive skin, start unscented. Our picks are Beauty Bare, our unscented Goat Milk Soap, and Clay Facial Soap.

What is lye soap?

"Lye soap" is simply soap. The FDA puts it plainly: ordinary soap is made by combining fats or oils with an alkali, such as lye. The FDA also notes that most body cleansers, liquid and solid, are actually synthetic detergents, even when they're sold as "soap" (FDA: Frequently Asked Questions on Soap).

So when you see sodium hydroxide on a handmade soap label, it's a sign you're holding real soap. If you've wondered how that compares to the bottle in your shower, we break it down in The Difference Between Body Wash and Soap.

Is there still lye in the finished bar?

No, not in a bar that's made and cured correctly. During saponification, the lye reacts with the oils and is used up. What's left is soap and glycerin, a natural moisturizer that many big manufacturers remove and sell separately. Handmade bars keep it.

The key word is "correctly." Too much lye makes a harsh bar. That's why every Ollie recipe is run through a lye calculator before we ever pour a test batch, and why we add a little extra oil (called superfat) on purpose so some oil stays in the bar to soften skin. You can see exactly how we do it in SoapCalc: The Science-First Soap Calculator Guide. Then every batch cures for at least four weeks so the bar hardens and mellows.

An honest note about pH

Healthy skin is slightly acidic, around pH 4.6 to 5.8 (Gonçalves et al., Anais Brasileiros de Dermatologia, 2017). True soap is alkaline. Studies of bathing soaps find most land around pH 9 to 10 (Tarun et al., Indian Journal of Dermatology, 2014). A well-made handmade bar like ours falls in that same range.

That doesn't make soap harmful. Your skin rebalances after you rinse. But it does explain why some people with very reactive skin feel tight after washing with any soap. If that's you, keep washing short, use lukewarm water and moisturize right after. Those habits matter as much as the bar.

Grandma's lye soap vs. today's handmade bars

Old-fashioned lye soap was three ingredients: lard, lye and water. It was firm, long-lasting and did everything from faces to laundry. Today's handmade bars use the same chemistry with ingredients picked for how they feel on skin.

Our bars keep a little of that tradition. Goat Milk Soap is made with goat milk, shea butter, beef tallow, lard, coconut oil, castor oil and sunflower oil. Tallow and lard make a hard, long-lasting bar, just like grandma's. Shea and sunflower condition, coconut gives lather, and castor keeps the bubbles creamy. Our Clay Facial Soap adds kaolin clay for a gentle face bar. (Curious about tallow? Start with Benefits of Tallow for Skin Care.)

Why goat milk?

Goat milk adds natural fats that make the lather rich and creamy, the kind that rinses clean without that squeaky feeling. It also contains small amounts of lactic acid. For the deeper dive, read What Does Goat Milk Actually Do for Your Skin? and What Is Goat Milk Soap and Is It Actually Better for Your Skin?

How to choose a gentle bar for sensitive skin

• Read the label. Look for a short list of oils, butters and sodium hydroxide (or "saponified oils"). If the list runs a paragraph long, it's probably not the gentlest choice.
• Skip fragrance if you react easily. Even natural essential oils can bother reactive skin. Unscented is the safest place to start.
• Skip scrubby add-ins on irritated skin. Oats, zest and seeds are lovely for exfoliation, but not on skin that's already angry.
• Buy from a maker who can answer your questions. A small-batch maker should be able to tell you their superfat, cure time and every ingredient. (Here's why small-batch skincare makes a difference.)
• Patch test first. Lather a little on the inside of your arm, rinse, and wait 24 hours.

Our picks for sensitive skin: Beauty Bare is our unscented Goat Milk Soap for face and body. Clay Facial Soap is our everyday face bar. Not sure which fits you? Take our Skin Quiz.

A note on eczema: Soap is not a treatment for eczema, psoriasis or acne. During a flare, many dermatologists recommend a mild or soap-free cleanser (Mayo Clinic), so check with yours. Many people with dry, sensitive skin do well with a simple unscented bar between flares. For more, see Common Mistakes in Sensitive Skin Care and Goat Milk Soap for Rosacea.

How to use lye soap on your face and body

Face: Wet your hands and the bar, work up a lather in your palms, and massage it over your face instead of rubbing the bar on your skin. Rinse with lukewarm water and follow with a facial oil like our Facial Oil or Night Facial Oil.

Body: Use lukewarm water, not hot. Lather with your hands or a soft Hand-Knit Cotton Washcloth. On days you want a deeper clean, an African Net Sponge gives gentle exfoliation (skip it on irritated patches). Pat dry, leaving skin a little damp, and moisturize within a few minutes. Mayo Clinic suggests within 3 to 5 minutes of bathing. Our Whipped Tallow and Body Balm are made for exactly this.

Shaving: A good bar makes a slick, cushiony shave lather. Work it up with a brush or your hands and shave as usual.

How long does a bar last?

Our 5 oz bars last about three to five weeks of daily use, depending on how many people share it and how wet it stays. The biggest thing you can do is let it dry between uses. A draining Soap Tray keeps it off the puddle and can add weeks to every bar.

Making lye soap at home? Safety first

Raw lye (sodium hydroxide) is caustic and can burn skin and eyes. It's a completely different thing from finished soap. If you make soap at home:

• Wear chemical-resistant gloves, long sleeves and eye protection.
• Work in a ventilated space, and always add lye to water, never water to lye.
• Use stainless steel or heavy plastic; aluminum reacts with lye.
• Run every recipe through a lye calculator before you start.
• If lye touches your skin, flush it right away with plenty of water. If it gets in your eyes, rinse immediately and keep rinsing, then get medical help. This is the standard first aid from the CDC (NIOSH Pocket Guide: Sodium hydroxide). Don't reach for vinegar; water is the first step.

Ready to try? Our step-by-step guide to cold process soap making walks you through it.

A simpler, lower-waste routine

One good bar can replace body wash, face wash and hand soap, with no plastic bottle at the end. When it's gone, all that's left is a sliver. Read more about our packaging and sustainability choices, and if you've heard soap is drying, harsh or "bad for your face," we tackle those in Soap Myths and Truths.

FAQ

Does lye soap still contain lye?

No. In a properly calculated and cured bar, the lye is used up during saponification. What's left is soap, glycerin and a little extra oil. If a bar stings, feels slimy or leaves redness, stop using it.

Is lye soap okay for kids?

A simple unscented bar is gentle enough for many kids. Baby skin is extra delicate, so check with your pediatrician before switching baby products, and keep bars where little ones can't chew them.

Can lye soap cure eczema, psoriasis or acne?

No. Soap isn't a medical treatment. A simple, unscented bar can be part of a gentle routine, but see a dermatologist for diagnosis and treatment.

How long does a bar last?

About three to five weeks of daily use for our 5 oz bars. Keep it on a draining soap tray so it dries between uses.

Which Ollie soap should I choose for sensitive skin?

Beauty Bare, our unscented Goat Milk Soap, or Clay Facial Soap for your face. See the whole lineup in our Goat Milk Soap collection.

Find your bar

Every Ollie bar is made by hand in small batches in Wisconsin. Shop the Goat Milk Soap collection, or come smell them in person at one of our markets and shops. Questions about your skin? Send me a note.

Sources: FDA, Frequently Asked Questions on Soap · CDC/NIOSH Pocket Guide to Chemical Hazards: Sodium hydroxide · Mayo Clinic, Atopic dermatitis: Proper bathing can reduce itching · Tarun et al., Evaluation of pH of Bathing Soaps and Shampoos for Skin and Hair Care, Indian J Dermatol 2014 · Gonçalves et al., Anais Brasileiros de Dermatologia 2017