When I was pregnant, I could smell people’s dandruff from across the room. Based on my estimate, at least 80% of people at the Carlingwood Mall during the winter of 2011 had dandruff. That probably wasn’t too far off – almost everybody, at some point, gets dandruff.

See all that dust in your house? It’s dandruff! (sort of). Dust is made up of lots of things, and dead skin cells are definitely in there. Do you ever wonder how many pounds of other people’s skin you breathe in every year? Now you will.

If you have dandruff, sometimes it goes away on its own, but sometimes it doesn’t, and sometimes it worsens and becomes seborrheic dermatitis. Seborrheic dermatitis is when the white dandruff flakes turn into yellow greasy flakes along with increased scalp irritation. Both dandruff and seborrheic dermatitis happen when the skin cells on your head change, usually because of a yeast called Malassezia and the bacteria Staphylococcus and Cutibacterium. Most everyone has these microorganisms on their skin, but if they overgrow, your scalp can become red, itchy and flaky.

If you find some flakes, what should you use? Does everything on the pharmacy shelf work equally? I have waded through the best available evidence (e.g., placeobo controlled clinical trials) to find which products have the best chance of working for you.

What Works Classification System for Dandruff

Classification

How much will it work?

Bottom Line
Green At least 25% more likely to clear dandruff that placebo / improves symptoms at least 25% more than placebo Best chance of working
Orange Less that 25% more likely to clear dandruff that placebo / improves symptoms at least 25% more than placebo Better than nothing
Red No evidence it will work Nope

Ketoconazole (such as Nizoral®) is an antifungal shampoo with the most evidence to work for dandruff and seborrheic dermatitis. People using ketoconazole are 31% less likely to have dandruff after 4 weeks compared to people using a placebo or non-medicated shampoo. A 31% difference in clearing up dandruff might not sound like a lot, but I would think the chances are even higher that it would at least improve your flaky situation.  You need to use it at least 2 to 3 times a week until your scalp is better, then use it once a week to prevent the dandruff from coming back.

Selenium sulfide (such as Selsun Blue®, Head and Shoulders Clinical Solutions Shampoo®), also an antifungal shampoo, cleared dandruff in 26% more people compared to placebo. Not bad. Not bad at all. It should be used daily until your dandruff is better, then 2 to 3 times a week

Zinc pyrithione (such as Head and Shoulders Itchy Scalp Care®) is another antifungal shampoo ingredient. There are no studies saying it will cure your dandruff like Ketoconazole or Selenium but, using it for 4 weeks could improve your symptoms by 47% more than if you used a placebo. Because Zinc pyrithione is more likely to improve symptoms than totally resolve your dandruff, I would try the above shampoos first. If those don’t work, give Zinc a try.

Shampoos containing salicylic acid (such as Neutrogena T/Sal®) also claim to help with dandruff by loosening, softening, and dissolving scaly skin. This might work a bit – it could improve your symptoms by 1.63 points out of 10. Would that be worth it to you?

What about Tea Tree Oil, doesn’t that cure everything? It might work to reduce symptoms like itchiness up to 11% more than a placebo. For this result, you will need to use it for at least 4 weeks and try the 5% shampoo if you can find it.

Like tea tree oil, Probiotics claim to work for lots of common ailments.  One study of people taking lactobacillus paracasei (1 billion colony forming units daily) for 57 days had improved scalp flakiness and redness by 35% more than those taking placebo. This sounds good, but I can’t seem to figure out where to buy this product. Maybe just eat more yogurt.

What about putting some Coal Tar (such as Dermarest Psoriasis Shampoo®, Tersa Tar Shampoo®) in your hair? Other than making your head smell like bad breath, it won’t do much for your dandruff. It might work for psoriasis, but there are no studies that show Coal Tar will improve dandruff or seborrheic dermatitis.

Honey, which I love, might work too. I am not sure how much it will help though, because the study using Honey in dandruff was difficult to find. When I finally found it, I had to pay to read it. So, I didn’t. But the gist of it was if you dilute honey in water (90% dilution), put it on your head, leave it for 3 hours (!), every second day for 2 weeks your dandruff might be a bit better. Don’t do this.

I hope this information helps you, and I hope the flakes stay outside, instead of inside, your house this winter!

 

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References:

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Davies, DB (1999). Comparative efficacy of shampoos containing coal tar (4.0% w/w; TarmedTM ) coal tar (4.0% w/w) plus ciclopirox olamine (1.0% w/w; TarmedTM AF) and ketoconazole (2.0% w/w; Nizoral® ) for the treatment of dandruff/seborrhoeic dermatitis. J Dermatol Treat, 10:177–183.

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