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Kiehl’s Since 1851 intensifies the bestselling Powerful-Strength Line-Reducing Concentrate.

Kiehl’s Since 1851 Powerful-Strength Line-Reducing Concentrate is a global phenomenon, selling at a rate of one per minute worldwide.

This year it takes a leap forward with the release of a new formula that boasts a higher percentage of vitamin C (12.5 percent) and the addition of hyaluronic acid.

A clinical trial with 52 women ages 36 to 65 demonstrated it’s measurably more effective than the original at reducing fine lines after two weeks of use, improving skin texture after four weeks, and minimizing forehead lines after eight weeks.

The serum feels warm as you spread it across the skin and seems to have an immediate tightening effect.

The great thing about Kiehl’s products is that they deliver results at accessible prices. The reformulated serum costs $62 for a 1.7 fl. oz. pump bottle, $81 for 2.5 fl. oz., and $104 for 3.4 fl. oz.

"Our renovated formula, now with hyaluronic acid and a greater amount of Vitamin C, provides faster, better results," says Kiehl’s scientific director Dr. Geoff Genesky,. "While vitamin C is difficult to stabilize within a formula, the team worked meticulously to stabilize even more vitamin C and deliver our most efficacious Powerful-Strength Line-Reducing Concentrate formula to date."

The new version is blended with 10.5 percent L-ascorbic acid and 2 percent vitamin Cg (ascorbyl glucoside).

L-ascorbic acid is an antioxidant that promotes collagen development for firmness, slows melanin production to avoid dark spots, and fights free radicals that damage skin.

Vitamin Cg (ascorbyl glucoside) is a synthetic form of the vitamin that has the same benefits and is considered more stable, i .e., slower to break down. (A bottle of Powerful-Strength Line-Reducing Concentrate has an 18-month shelf life after it’s opened.)

Hyaluronic acid attracts moisture and retains it for plump, younger-looking skin. According to one study, it can hold up to 1,000 times its weight in water, which is why it’s used in many treatment products.

Find Kiehl’s Powerful-Strength Line-Reducing Concentrate at Kiehl’s Since 1851, where they typically offer free samples so you can try before you buy, and at Neiman Marcus and Nordstrom.