This Is Why Your Dandruff Shampoo May Not Be Cutting It

Imagine buying a dandruff shampoo, excited that those pesky white flakes will finally stop falling from your head and that constant itch on your scalp will cease to exist. You use it for a week or two and see no change, but that's expected. You give it another week, and still nothing. Now a full month goes by, and the flakes are still all over your clothes and sheets, and you’re still constantly itching.

What gives? There could be a few reasons why it’s not working. Before you throw out that shampoo, read this first.

Dandruff vs. Seborrheic Dermatitis

People often confuse a simple dry scalp with dandruff — and throw in seborrheic dermatitis, and it becomes a guessing game. That's because their symptoms can overlap significantly. “It isn’t always possible to distinguish them at home,” says Hadley King, M.D., a board-certified dermatologist based in New York City.

According to the Mayo Clinic, seborrheic dermatitis is a skin condition that can cause scaly patches, inflamed skin, and dandruff. Symptoms can include everything from flaking skin, patches of greasy skin covered with flaky white or yellow scales, rashes, and itchiness. It affects oily parts of your skin so it can appear on your scalp, your body, and even your face. Dandruff, a form of seborrheic dermatitis, is milder and is defined as a common condition that causes your scalp to flake.

“The important distinction is that dandruff is an inflammatory scalp condition and not simply dry skin,” says King. “That’s why treating it with a moisturizing shampoo alone may not be enough.”

If you’re trying to figure out if you have dandruff or a more severe case of seborrheic dermatitis, you might need to see a board-certified dermatologist (more on that later).

The Causes

Because dandruff is the mildest form of seborrheic dermatitis, they share the same underlying root causes. According to the National Eczema Association, the exact cause can’t be pinpointed precisely. Still, the condition is believed to involve a combination of genetics, an overgrowth of a natural fungus called Malassezia yeast that feeds on oils in the skin, and an inflammatory skin response.

Specific flare-ups and triggers for both conditions include stress, hormonal changes, illness, or stressful life events, such as the death of a loved one. The Mayo Clinic notes that cold, dry weather, certain medications, and harsh shampoos and styling products can also trigger or worsen symptoms. While mild dandruff can often be managed simply with an over-the-counter dandruff shampoo, more severe cases of seborrheic dermatitis feature pronounced inflammation and may need further attention.

How to Treat Dandruff

There is a right way and a wrong way to use a dandruff shampoo. Dandruff shampoos, according to Marisa Garshick, M.D., board-certified dermatologist at MDCS Dermatology, usually include the following active ingredients: ketoconazole, zinc pyrithione, selenium sulfide, and salicylic acid. Garshick explains that ketoconazole, zinc pyrithione, and selenium sulfide help reduce the growth of the Malassezia yeast that lives on your scalp and contributes to dandruff. Salicylic acid, on the other hand, exfoliates the scalp and removes excess flakes and buildup.

Garshick says it’s best to leave a dandruff shampoo on the scalp for about three to five minutes before rinsing, to give the active ingredients enough contact time to work. (It’s also important to follow the shampoo's instructions for more precise guidance, as they may vary.) You’ll also want to be consistent, as she says dandruff shampoos must be used regularly for several weeks to see improvement.

According to the American Academy of Dermatology, you can use dandruff shampoo for mild to moderate cases of seborrheic dermatitis. It says the same ingredients (ketoconazole, zinc pyrithione, and selenium sulfide) used to reduce the growth of yeast that causes the flakes may help. Salicylic acid helps exfoliate flakes but may not address the underlying yeast growth.

However, dandruff shampoos can fall short when inflammation is significant, itching is persistent, or scaling is thick. Garshick says that if someone has used a dandruff shampoo consistently for several weeks without improvement, or if symptoms worsen, it is time to see a board-certified dermatologist.

How to Treat Seborrheic Dermatitis

For more significant inflammation, Garshick says prescription topical corticosteroids may be recommended for short periods to help reduce redness and itching, or nonsteroidal prescription treatments. Seborrheic dermatitis is a chronic, recurring condition, she adds, and consistent treatment helps prevent flare-ups.

King adds that a dermatologist can distinguish dandruff from other conditions (psoriasis, eczema, allergic contact dermatitis, infection, etc.) or provide a stronger shampoo, topical anti-inflammatory medications, or other treatments. “The key is to make sure you have the right diagnosis,” she says.

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