Every year on the winter solstice, around 21 or 22 December, bathhouses and homes across Japan float whole yuzu in the bath. The custom is called yuzuyu (柚子湯), and it's the reason we built Miyomi around this one fruit. Here's where it came from, how to do it yourself, and what yuzu does and doesn't do for skin.
What Yuzu Is
Yuzu is a small, bumpy citrus about the size of a mandarin, with a thick, fragrant rind and not much juice. In Japan it's harvested from October to December. The smell is what people remember. It's a bit like mandarin and grapefruit, with a floral edge you don't get from lemon or lime.
It's also slow to grow. A Japanese saying about fruit trees goes momo kuri sannen, kaki hachinen, yuzu no ōbaka jūhachinen: peaches and chestnuts take three years to fruit, persimmons eight, and yuzu, "the big fool", eighteen. That's for trees grown from seed, and growers graft them to speed things up, but it gives you a sense of why the fruit has always felt a little special.
The Winter Solstice Bath
Yuzu baths go back to the Edo period (1603 to 1868). The usual story is that public bathhouses started adding yuzu on the solstice to bring in customers. A pun helped it catch on. Tōji (冬至) means winter solstice, and tōji (湯治) means a stay at a hot spring. Yuzu also sounds like yūzū (融通), which means flexible or accommodating.
The bath was said to keep colds away all winter. Nippon.com, in its guide to the solstice, suggests that promise is probably optimistic. The reason people keep doing it is simpler. In the coldest, darkest week of the year, a hot bath that smells of citrus feels good. Plenty of families also eat kabocha pumpkin on the same day.
Our winter solstice falls around 21 June, which makes June the natural time for a yuzu bath here. Yuzu is grown in Australia in small amounts and is hard to find in shops, so most people use yuzu peel oil, or bath salts made with it, instead of whole fruit.
How to Run a Yuzu Bath at Home
- Whole fruit. Float three to five whole yuzu in a warm bath. Squeeze or roll them in your hands now and then to release more scent.
- Cut fruit. Halving them makes the smell stronger, but the peel oil can make skin tingle, and pulp and seeds end up everywhere. Put cut fruit in a mesh or cloth bag.
- No fresh yuzu. Use bath salts made with real yuzu peel oil. On the ingredient list it may appear as Citrus junos peel oil. "Yuzu fragrance" can be a synthetic blend.
- Temperature. 38 to 40°C is plenty. Very hot water makes any tingle worse and dries skin out.
For the rest of the routine, including how much salt to use and how long to soak, see how to use bath salts.
What Yuzu Oil Does for Skin
Most of yuzu's fragrance sits in tiny oil glands in the rind. Studies of yuzu peel oil find it is mostly limonene, often around three quarters of the oil, with smaller amounts of compounds like γ-terpinene and linalool that shape the scent.
In a bath, that oil's main job is the scent. You'll see yuzu sold as a vitamin C ingredient, but vitamin C dissolves in water, not oil, so it doesn't end up in the peel oil. A yuzu oil bath isn't a vitamin C treatment, and we don't claim ours is.
How your skin feels after a yuzu bath comes mostly from the rest of the bath: warm water, softened with bicarb, and moisturiser once you've patted dry. The smell stays with you for a little while afterwards, which is most of the point.
Who Should Take Care
Limonene and linalool are on the European Union's list of 26 fragrance ingredients that must be named on labels, because some people are allergic to them. If you've reacted to citrus peel or perfumes before, patch test first. Dissolve a pinch of bath salts in a little water, dab it on your inner forearm and wait a day. Skip scented baths on broken or irritated skin.
Using Miyomi
Miyomi is our version of the solstice bath for a country where fresh yuzu is hard to come by: Epsom salts and bicarb soda with cold-pressed yuzu peel oil and sencha green tea extract. Two scoops make a full bath.
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