Here's what a dermatologist thinks about this anti-dandruff shampoo—and it's on sale for Presidents' Day

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Users call this shampoo everything from a "game changer" to a "miracle worker" — and one dermatologist weighs in. (Photo: Getty Images)

One of Amazon’s best-selling shampoos has more than 6,000 reviews and a 4.5-star rating—and it’s an anti-dandruff formula. Nizoral A-D Anti-Dandruff Shampoo (on sale for $13.50 with on-page coupon for Presidents’ Day, was $17) is one of the site’s most popular beauty products and gets high praise from users and dermatologists alike. Reviewers, who some say discovered the products due to a dermatologist recommendation, call it everything from a "game changer" to a "miracle worker" — and one dermatologist agrees.

“Nizoral is one of my favorite shampoos for treating seborrheic dermatitis,” Michelle Henry, MD clinical instructor with Weill Cornell Medical College tells Yahoo Lifestyle. "It affects sebaceous, oil gland-covered regions of the scalp, face, and trunk.” The condition, which is caused by a yeasted called Malassezia, results in redness, itching, scaly patches and flaky skin.”

When it comes to the scalp, Nizoral works wonders. The shampoo is clinically proven to obliterate dandruff, itchiness and gets to the root of the problem, thanks to an active ingredient called ketoconazole. Henry says ketoconazole is, "effective against Malassezia, therefore, It treats the cause, not just the symptoms, of seborrheic dermatitis." And the directions indicate that using this twice a week is all it takes to see results.

Nizoral A-D Anti-Dandruff Shampoo. (Photo: Amazon)

"I have autoimmune issues that make me prone to seborrheic dermatitis. I also work with exotic animals, and occasionally they can develop tinea and other fungal dermatitis, and I am exposed," explains a 5-star reviewer. "My dermatologist had given me prescription strength ketoconazole shampoo, which I found irritated my skin, damaged my hair and took a while to show any results. I'm not sure how, but this shampoo works way better than any cream, spray or shampoo I've used and also reduces redness and irritation right away. Immediately results after one use, skin was completely cleared up after the second day. A little goes a long way too, so happy to have found this."

Bottom line says, Dr. Henry, "It works, and it's cost-effective."

The reviews quoted above reflect the most recent versions at the time of publication.

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