ESK, the Australian cosmeceutical brand cofounded by Dr. Ginni Mansberg and Daniel Rubinstein, has found a new celebrity collaborator.

Enter Selma Blair, who codeveloped the brand’s Ultimate A Gold, a more potent alternative to its hero product Ultimate A. The product features retinol, niacinamide, lactic and glycolic acids, and 4-n-butylresorcinol to target melasma and pigmentation. It launches Wednesday on ESK’s website for $100.

Blair discovered the brand via her aesthetician after years of undiagnosed multiple sclerosis left her skin inflamed. “Once I used this ESK calming cleanser for a week, I noticed a difference in the inflammation, and the rosacea went down,” she said. “I knew Retin-A was too active for me, and I sought out the brand because I loved that I could get this online and that it wouldn’t be aggravating.”

Though her skin concerns have changed, she was skeptical that any product with those levels of active ingredients would be tolerable. “I didn’t believe that there could be a Retin-A type of product that could work for me,” she said. “I knew I wanted the niacinamide, and the butylresorcinol. Dr. Ginni is very, very careful about knowing what could be inflammatory.”

The genesis of the product happened in chunks. “We developed one of our first products with retinol and niacinamide, and then we had a version that includes glycolic acid,” said Rubinstein. “Then we added a hydroxyacid, which took time for us to get stable. Then we added in more for barrier and hyperpigmentation. So, Ultimate A Gold has been going for 12 years.”

The brand came into being over a decade ago, Rubinstein said, as a result of the growing appetite for simplified skin care. “We felt both very interested and then outraged by some of the nonsense in the marketplace,” Rubinstein said. “Eventually, we got into an idea to collaborate with surgeons, dermatologists and cosmetic physicians in Australia to come up with something that was truly evidence-based, and we launched in 2017.”

Among the need states he was hoping to solve for, “particularly with aging and hyperpigmentation, there are very few good options which are really well-tolerated,” he said. “There are some very good products out there, a lot of them are prescription-grade, and we find that up to 60 or even 70 percent of women are experiencing skin sensitivity.”

Of Ultimate A Gold, “We followed the evidence, there was a good correlation between retinaldehyde, niacinamide, butylresorcinol. And it’s actually very gentle and restores barrier function. We didn’t necessarily expect that,” Rubinstein said. “All of this stuff has been evolving for solutions that are highly effective and well-tolerated. That’s where we see the demand in the marketplace.”

When asked if there were any other products Blair would like to cocreate, she said, “I’m starting to work again, I’m wearing makeup again, I’m washing my face in a different way. There’s always something, but I’m pleased with my skin right now, actually. I’m just excited to see what the things are that we need as we go.”