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Does Persimmon Soap Actually Work? What the Science Says (and What Users Report)

The nonenal science is real. The proof that persimmon soap removes it is thinner than the labels suggest. Here's where the evidence stands, and why so many people still swear by it.

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Type “is persimmon soap” into Google and the suggestions tell you how people feel about it: legit, a hoax, a gimmick, worth the hype. It’s a fair question. The bars aren’t cheap, the labels make big promises, and the smell they target is one most of us would rather not discuss.

So we went through the published research and hundreds of public comments from people who have used it. Here’s the short answer, followed by the detail. This page is about whether the soap works; if what you actually want to know is whether a particular listing and its reviews can be trusted, that is a different investigation and it is over at is persimmon soap legit.

What is nonenal, and is “old person smell” real?

Yes. The best-known study came from Shiseido researchers in 2001. They analyzed body odor from people aged 26 to 75 and analyzed it with gas chromatography–mass spectrometry. 2-Nonenal, an unsaturated aldehyde with a greasy, grassy smell, turned up only in the participants aged 40 and over. It correlated with omega-7 fatty acids and lipid peroxides on the skin. The authors suggested it “may be involved in the age-related change of body odor.” That “aged 40 and over” figure is a detection threshold for a gas chromatograph rather than a statement about when anyone can smell you, which is why the age this smell actually starts has two different answers about thirty years apart.

A 2016 study measured emissions from the nape of the neck and found that 2-nonenal rose with age in both men and women. More recent work has focused on building sensors to detect it. The science on what the smell is holds up well.

Why persimmon? The tannin theory

Kakishibu is fermented juice from unripe, astringent persimmons. Japan has used it for centuries as a dye, a wood and paper preservative, and a deodorizer. The active part is persimmon tannin, a condensed tannin with many binding sites.

The theory behind the soap works like this:

1. Nonenal forms in the oily film on older skin.
2. Regular soap lifts oil, but some odor molecules stay behind.
3. Tannin in the lather binds the aldehyde, so it rinses off with the water instead of lingering.

What supports this? The key document is a patent filed in 2000 by researchers at Menard Cosmetics (JP2001-302483A). When we first wrote this post we could only read it through a secondary summary. We’ve since read the full patent, and the details matter:

• The lab test was a jar, not skin. A 1 g sample was sealed with nonenal gas for 10 minutes, then the remaining gas was measured by gas chromatography against a blank. The patent reports that condensed persimmon tannin removed more nonenal than the commercially available deodorant ingredients it was compared with.
• The human test was self-rated. For each formula, 10 people who said they had age-related odor used it daily for two weeks and scored it themselves on a 5-point scale. Nobody measured their odor.
• The products tested weren’t soap. The formulas were leave-on skin products (the patent lists mists, gels, lotions, aerosols and emulsions). A soap you lather and rinse off is a different situation, and nobody has published a test of it.

It’s company data, not peer-reviewed, and it’s more than 25 years old. It’s still the closest thing to direct evidence that exists.

The other tannin evidence is about other smells. A 2011 Japanese dental study found that a 1% persimmon tannin rinse reduced sulfur compounds in bad breath in 100 people. A 2025 study found that a 0.1% persimmon tannin gel lowered hydrogen sulfide and methyl mercaptan in dogs’ mouths over a month, although gum and plaque scores didn’t change significantly. A 2026 lab study described how persimmon polyphenols remove ammonia and hydrogen sulfide. All of that supports tannin as a deodorizer of sulfur and ammonia gases. None of it is skin, and none of it is nonenal, which is an aldehyde and a different kind of molecule.

Is it the persimmon, or just the washing?

It’s the sharpest question skeptics ask. In an r/Menopause thread one reader wondered why it had to be persimmon rather than any other fruit acid. Another pointed out that a soap only stays on your skin for a minute.

Here’s what’s known:

• Any soap removes some nonenal. 2-Nonenal is oily and practically insoluble in water (PubChem). It leaves with the skin oil it forms in. Soap lifts skin oil, so washing the right areas more carefully should help whichever bar you use. That may be part of why people who switch to persimmon soap and start scrubbing their neck and scalp see a change.
• Tannin is the proposed extra. The idea is that tannin also binds whatever nonenal is left. The jar test above is the only direct evidence for that.
• No one has compared persimmon soap with plain soap. There’s no head-to-head test on people. So “it works for me” can’t tell you whether the persimmon or the new routine did the job.
• The only human study that measured nonenal wasn’t about soap. In Willems 2022, 14 middle-aged and older adults took blackcurrant powder for seven days, and nonenal from the back of the neck fell by more than 25% against control. That was diet, and it was one small study.

The fair version of the skeptics’ point is that the product evidence is weak, not that the smell is invented. The chemistry of 2-nonenal comes from peer-reviewed journals. Our nonenal research index lists every study, including where they disagree.

The acid products that come up in the same threads (glycolic acid, mandelic-acid washes) are mostly used on the underarms. That’s usually a different, bacterial odor from sweat, not oxidized skin oil. Our perimenopause body odor guide explains how to tell the two apart, and we put the two product categories directly side by side in persimmon soap vs Lume. The other answer those threads reach for, a hypochlorous acid spray, is a disinfectant, so it is aimed at the bacterial smell as well.

What real users say

We read hundreds of comments across r/Menopause, r/Perimenopause, r/AskWomenOver60, r/bodyodor, r/hygiene and r/AusSkincare. The pattern was consistent.

When it works, people are surprised by how well. Menopause and perimenopause threads are full of posts titled “persimmon soap really works” and “thank God for persimmon soap”. Several people describe buying it for a father or husband and noticing the difference on his neck and pillow.

When it doesn’t, the odor usually wasn’t nonenal. In r/bodyodor, where many posters are younger and dealing with sweat or bacterial odor, the replies are much cooler: “didn’t work for me,” “don’t waste your money.” One commenter summed it up:

Skeptics raise fair points. In r/AusSkincare, one commenter noted that most of the data comes from the companies themselves. That’s a fair criticism, and it matches what we found. A few users also say it did nothing, or that the smell seemed worse at first. Our list of reasons persimmon soap doesn’t work covers the usual causes. If it stings or dries you out, see persimmon soap side effects.

Does persimmon soap have a scent?

This is the question readers actually stop to ask in those threads, and it almost never gets a straight answer. In an r/hygiene thread in late August, two people asked it independently — does the soap leave a lingering smell, and what does persimmon even smell like — and a third chimed in to say she wanted to know too. The replies contradicted each other within a few comments. One reader reported no “after smell” at all. Another said hers smelled lovely. A third had braced for something aggressively fruity and was relieved to find it neutral.

All of them were telling the truth. They were using different soaps.

“Persimmon soap” is not one product, and scent is the spec that varies most across the category. Here is what the five bars in our best persimmon soap comparison say about themselves, each read off the maker’s own page:

• TanniBar is sold only as fragrance-free, with no perfume and no essential oils (brand page). Disclosure: we own this one.
• Mirai Clinical sells an unscented version alongside scented ones — lavender, citrus and mint — with the unscented bar listed a couple of dollars cheaper.
• Pelican has a light citrus scent, from fragrance or essential oils depending on the version.
• Asayu Japan lists no added fragrance, but the bar contains Japanese red pine leaf oil, which carries its own aroma.
• Natrulo is scented with lemongrass essential oil.

So three of the five arrive with a scent by default, one is sold both ways, and one doesn’t offer a scented version at all. If you ask a room full of users whether persimmon soap smells and get five answers, that is the reason.

Don’t expect it to smell of persimmon

The name sets an expectation it doesn’t meet. Persimmon tannin is the compound responsible for the fruit’s astringency — the pucker in an unripe persimmon. The research on it treats astringency as a texture-and-taste problem measured as soluble tannin content: in a 2025 postharvest study, carbon dioxide and ethylene treatments both cut soluble tannin to make an astringent cultivar edible. That is food science rather than anything to do with skin, but the point carries: astringency is something you feel, not something you smell. Whatever a persimmon bar smells like comes from its added fragrance or from the soap base, not from the tannin.

“Fragrance-free” is a label, not a guarantee

It is worth reading the ingredient list rather than the front of the pack. A 2026 analysis in Contact Dermatitis screened 300 moisturisers sold in Tunisia against their declared ingredients: fragrance was the most common allergen, present in 84.7% of them, and only 15.3% were free of both fragrance and plant extracts. Of the 53 products labelled fragrance-free, 46 — 86.8% — actually were (Kemicha 2026). Those were moisturisers in one national market, not soaps, so don’t read a precise failure rate across to this category. Read the habit instead: look for parfum, fragrance, aroma or a named essential oil on the list, because the label word is not regulated as tightly as it sounds.

Scent matters here for three separate reasons:

• If you are testing whether the soap works, a fragrance gives you a second smell sitting on top of the one you are trying to judge. That is reason seven in our list of reasons persimmon soap doesn’t work, and it is the quietest way to waste a two-week trial.
• If your skin is reactive, fragrance is the ingredient most likely to cause trouble, on top of the dryness tannin can cause on its own — see persimmon soap side effects.
• If you are buying it for somebody else, which is remarkably common in these threads, an unscented bar can replace what’s in their shower without announcing itself. We go through that situation properly in how to tell an elderly parent they smell.

So, should you try it?

Persimmon soap is a reasonable, low-risk experiment if:

• you’re over roughly 40 (or going through menopause) and notice a stale, oily or “dusty” smell,
• it’s strongest on the neck, scalp, pillowcases or collars rather than your armpits,
• ordinary washing and deodorant haven’t shifted it.

Not sure you have it at all? Most people can’t smell their own skin odor. Our pillowcase check is a simple way to find out.

It’s probably not the right tool if your odor is sharp and sweaty, localized to the armpits or groin, sudden, or accompanied by other symptoms.

If you do try it, technique matters as much as the brand. Use it daily on the right areas, let the lather sit briefly, and wash your bedding at the same time (here’s why a normal cold wash often isn’t enough). The chair you sit in every evening holds its own supply and keeps releasing it, which is a large part of why some people get two good weeks and then feel the smell come back — we work through that in getting the smell out of furniture. Our step-by-step guide covers the routine, and our comparison of five bars shows how they differ on scent, price and guarantee.

Our pick · our product

TanniBar Persimmon Tannin Bar

If you'd rather not add a new scent while you test it, TanniBar is fragrance-free and has a 30-day refund with no return needed.

Check price →We own TanniBar and earn from sales. 30-day refund, no return needed.

The bottom line

The science clearly supports nonenal as a real, age-linked odor, and it gives a plausible reason tannins could help. It doesn’t yet include a proper trial of persimmon soap on people. The one company test we could read in full used self-ratings and leave-on lotions, not soap. User reports fill some of that gap, and for the specific smell it targets, they’re mostly positive. Go in with realistic expectations, a fair test period and a good refund policy.

Frequently asked questions

Sources