What Is Japanese Indigo, and Should You Add It to Your Skin-Care Routine?

Japanese indigo is touted for its calming, anti-inflammatory effects, and it may provide benefits for people managing certain skin conditions, though research is limited and emerging.

May Help Manage Psoriasis

Most of the existing research on the topical skin-care benefits of Japanese indigo addresses psoriasis, an autoimmune disorder where skin cell growth goes into overdrive, leading to inflammatory plaques and scales on the skin, according to the National Psoriasis Foundation.

One review and meta-analysis of preliminary research, which analyzed a variety of plant extracts in the management of psoriasis, found that certain compounds in Japanese indigo may reduce inflammation and suppress cell growth, which may be helpful in psoriasis treatment.

It’s possible that benefits for psoriasis can be traced back to the two active compounds, indirubin and tryptanthrin. “Studies have shown that indirubin can improve psoriasis without serious adverse side effects by reducing the size and density of patches on the skin,” Dr. Sobel says. “It works to block and inhibit the communication between cell activity that causes moderate plaque psoriasis.”

Meanwhile, tryptanthrin “works to decrease the molecules in the body that promote inflammation, [which is] the root cause of psoriasis,” Sobel adds. “Together, these ingredients address the cause and effect of inflamed skin conditions,” he explains.

As the authors of the aforementioned review and meta-analysis note, Japanese indigo evidence from clinical trials is “limited but consistent.” And since the publication of that research, a more recent review on the ingredient came to similar conclusions: Japanese indigo acts on specific pathways that decrease inflammation and cell proliferation, and suppress new blood cell growth in similar ways to drug treatments. (This is not to say that it’s as effective, or a substitute for, drug treatments.) Still, as the review authors point out, despite its potential promise, the ingredient is still being explored as a theoretical treatment for psoriasis, and much more research needs to be done.

May Help Soothe Eczema

While Japanese indigo is commonly used to help treat eczema, there are fewer studies suggesting its efficacy on this skin condition than psoriasis.

That said, one small randomized, double-blind clinical trial found that topical application of Japanese indigo ointment helped treat atopic dermatitis — the most common form of eczema — in 48 participants ages 6 to 65 when used twice daily over six weeks. Those who received the Japanese indigo (32 people) saw their eczema severity decline by about 50 percent, while the placebo cream group (16 people) had a reduction of about 20 percent. In addition, the Japanese indigo group also had a smaller body surface area affected with dermatitis and reported a higher quality of life after the six weeks.

One popular skin-care product containing this ingredient, the Indigo Soothing Triple Recovery Cream by Tatcha, has a Seal of Acceptance from the National Eczema Foundation indicating its suitability for eczema-prone skin, though Japanese indigo is not an FDA-approved treatment for eczema or any dermatological conditions yet.

May Calm Rosacea

Clinical studies supporting the use of Japanese indigo for rosacea are scarce, so more research is needed to provide conclusive evidence on this front.

Right now, the ingredient provides theoretical benefits for rosacea. “Tryptanthrin has been shown to exhibit antioxidant, anti-inflammatory, and antimicrobial effects on the skin. This may explain any [possible] benefits in treating rosacea,” says Zeichner. “We also know that mites that live on the skin as part of the normal microbiome contribute to inflammation and bumps,” he adds. Tryptanthrin may lower levels of these skin mites and calm inflammation, which is how rosacea is biomedically treated.

Zeichner recommends sticking to conventional prescriptions for rosacea treatment. You can certainly use a cream containing Japanese indigo, he says, but at this time, it’s not recommended to abandon current, doctor-recommended prescriptions in favor of one of these products.

Additional Possible Benefits of Japanese Indigo for Skin

Zeichner says this ingredient “may also be helpful in protecting the skin against environmental-induced free radical damage,” which some research supports. Such sources of skin damage include exposure to UV rays, pollution, smoke, and even stress, so Japanese indigo may be a worthy addition to your skin-care regimen to ward off dullness and signs of premature aging.

Last, Sobel says Japanese indigo boasts antibacterial properties, “making it a good addition to anti-blemish products.” This additional benefit to clear up breakouts isn’t too surprising, since acne is also an inflammatory skin condition; but there is no research yet to substantiate this potential benefit.