How Do You Get Rid of Dandruff?

Researched and written by Curl Centric. Read by an AI voice.

Dandruff isn't just a dry scalp, and the oil you add may be feeding it. We explain what causes it, how to use a dandruff shampoo when you only wash once a week, and when flakes need a doctor instead.

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The full guide, with every source: Why Do I Still Have Dandruff After Washing My Hair?

Transcript

This is Curl Science by Curl Centric.

If you've ever had flakes show up in your part a few days after wash day, you've probably reached for a hair oil or grease. It feels like your scalp is dry, so you give it oil. But dandruff isn't simply a dry scalp, and that oil may be feeding it. In this episode, we'll tell you what dandruff actually is and why putting oil on your scalp can backfire. Then we'll explain how to use a dandruff shampoo when you only wash once a week, and when it isn't dandruff at all.

Dandruff is flaking and itching on your scalp, and it's one of the most common scalp problems there is. You can't catch it from anyone, and it isn't a sign that your hair is dirty. Washing less often can make the flakes easier to see, but it doesn't cause them.

It starts with a tiny yeast called Malassezia. A yeast is a type of fungus, and this one lives on almost everyone's scalp. It can't make its own fats, so it feeds on the oil your scalp makes.

As it feeds, it breaks that oil apart and leaves some of the pieces behind, including one called oleic acid. On some scalps, those leftovers are irritating, and the irritated skin itches and flakes.

So why doesn't everyone get dandruff? Researchers put pure oleic acid on people's scalps. On scalps that weren't prone to dandruff, nothing visible happened. On dandruff-prone scalps, it caused flaking. So dandruff isn't about catching something. It's about how your scalp reacts.

That's why dandruff and a dry scalp are so easy to mix up. The flakes are dead skin either way, and the American Academy of Dermatology says it can be tricky to tell them apart without a dermatologist. A dry scalp often comes with dry skin elsewhere on your body. One practical clue is what makes it better. A dry scalp usually improves with a gentle, regular shampoo, while dandruff gets better with a dandruff shampoo.

Dandruff is considered the mildest form of seborrheic dermatitis. When the condition becomes more inflamed, the itching, scaling, and irritation can become more intense. On darker skin, that irritation often looks pink, purple, or lighter than the skin around it instead of red.

Now, back to the oil. If the yeast feeds on oil and leaves oleic acid behind, what happens when you add more oil? Olive oil is 55 to 83 percent oleic acid. Coconut oil is about 5 to 10 percent. But no study has tested oiling a dandruff-prone scalp, so we can't tell you that it definitely makes dandruff worse.

The American Academy of Dermatology does advise using pomade sparingly because it can lead to flare-ups. And the Mayo Clinic says products that build up on your scalp can cause more dandruff. So while you're treating it, keep your oils on your hair strands and ends instead of your scalp. You can still give your curls the oil they need without coating your scalp.

Before we get to what actually works, one quick ask. If you want more answers like this, follow the show, so the next one finds you.

A dandruff shampoo works because of its active ingredient, and you'll find it in the Drug Facts box on the bottle. The American Academy of Dermatology names zinc pyrithione, selenium sulfide, ketoconazole, salicylic acid, coal tar, and sulfur. The first three go after the yeast. Salicylic acid and coal tar help with the itching and flaking.

In one trial of people with severe dandruff or seborrheic dermatitis, a shampoo with 2 percent ketoconazole improved dandruff severity by 73 percent in four weeks. A shampoo with 1 percent zinc pyrithione improved it by 67 percent. In the United States, 1 percent ketoconazole is sold over the counter, while the 2 percent strength used in that trial requires a prescription.

A ready-made shampoo with 5 percent tea tree oil also beat a plain shampoo in one trial, improving dandruff by 41 percent compared with 11 percent. That study tested a properly formulated shampoo, not tea tree oil drops added at home.

One caution about coal tar. It can make your scalp more sensitive to the sun, and it can discolor light, bleached, or tinted hair.

How you use your dandruff shampoo matters as much as which one you pick. Part your hair so you can reach your scalp. Put the shampoo on your scalp only, because the ingredients that treat dandruff can dry out your curls. Massage it in, and then leave it on.

The American Academy of Dermatology says some dandruff shampoos need up to 5 to 10 minutes on your scalp before you rinse. Most bottles only say to lather and rinse, so check the directions on yours. In one small study, leaving the shampoo on for five minutes worked better than rinsing it off right away. Then rinse thoroughly, and shampoo and condition your hair with your usual products.

How often should you use it? Most labels say at least twice a week because they're written for everyone. For curly and coily hair, the American Academy of Dermatology says to use your dandruff shampoo about once a week if your hair tolerates it. So if you only wash once a week, giving the shampoo enough time on your scalp matters.

Give it about four weeks. Once your scalp clears, don't stop completely because dandruff tends to come back. In one six-month study, 47 percent of people using a plain shampoo relapsed, compared with 19 percent who kept using prescription 2 percent ketoconazole once a week. If one shampoo doesn't work, try one with a different active ingredient.

Stress can make a flare-up worse, and flare-ups are most common in winter and early spring. But no clinical trial shows that cutting out sugar or dairy, or taking a supplement, clears dandruff.

Now, the most important part if you have young children. Dandruff usually starts around puberty, so a flaky, itchy scalp in a young child may be scalp ringworm instead. Despite the name, there's no worm. It's a contagious fungal infection. In the United States, it's most common in children aged 3 to 9, especially Black and Latino children.

Early on, it can look like plain flaking. Later, there may be scaly bald patches or black dots where hairs have broken off. Shampoo alone won't cure it. It needs prescription medicine taken by mouth, and severe cases can scar and leave permanent bald spots if they aren't treated. A study found no link between scalp ringworm and oiling, hairstyles, or other hair care practices. What mattered was contact with someone who had it. So if a young child has a flaky scalp, especially with broken hairs or bald patches, see a doctor instead of reaching for dandruff shampoo.

In adults, scalp psoriasis can look like dandruff, with thicker, silvery scale. A reaction to hair dye or a styling product can look similar. And if your crown itches or burns and your hair is thinning there, see a dermatologist. That can be an early sign of a scarring type of hair loss called CCCA.

Dandruff itself doesn't cause bald patches. A few small studies link it to somewhat more shedding. But if you have patches of hair loss or a widening part, don't wait on a shampoo. See a dermatologist.

So here's what we'd do. Keep oils off your scalp while you treat it. Put a shampoo with an active ingredient on your scalp only, and leave it on for a few minutes before you rinse, about five if the directions allow. If you have curly or coily hair, use it about once a week if your hair tolerates it. Give it four weeks, then keep up a maintenance wash about once a week. And if it doesn't clear, or a child has a flaky scalp with broken hairs or bald patches, see a doctor.

We put the shampoo trials and what each ingredient does in our dandruff guide, and the link is in the show notes. And if this helped your scalp, follow the show for the next one.

That's it for this episode. If it helped, follow Curl Science in your podcast app so the next one reaches you, and leave us a rating while you're there. Curl Science is researched and written by the Curl Centric team, and it's read by an AI voice.