The weather may actually be giving you dandruff

Ever noticed how your scalp gets flakier during certain parts of the year? This is normal and you’re far from alone! What you might not expect is that there isn’t one season that makes it worse for everyone. In fact, any season can potentially trigger dandruff flare-ups. 

This is because dandruff is complicated! Your flakes are the result of a complex cycle taking place under your skin at all times. Briefly, your skin produces oil, Malassezia — a type of yeast that naturally lives on the skin, eats that oil, and then releases waste products that trigger your immune system. The flakes you see come from your immune system making new skin faster to get those waste products off you. The problem is that dead skin cells can only ‘disappear’ into the air so fast. So when your skin is making new cells faster than the old ones can go away, they clump up, those clumps fall onto your shoulders, and embarrass you. 

Changes in humidity, temperature, sunlight, sweating, indoor heating, and even rapid swings between hot and cold environments may help explain why your flakes ebb and flow throughout the year [1-6].

Cold & Dry

Temperature and humidity influence how much water the skin loses, how much oil and sweat it produces, and how well the skin barrier functions. Which matters because it can drastically affect the dandruff cycle. For example, people who live in temperate climates often report more dandruff flareups in the fall and winter. In one study examining more than 5,000 cases of seborrheic dermatitis (a more extreme form of dandruff)  in Istanbul, diagnoses were highest during the colder months and lowest during June and July. In other words, people got flakier in the colder months [3]  But why? 

It turns out that cold, dry air weakens the skin barrier via dehydration. When humidity drops, water in your skin barrier evaporates faster, thus leaving you more vulnerable to Malassezia blooms. This problem gets worse the colder it gets, and that’s because central heating can significantly reduce indoor humidity, meaning your scalp may repeatedly move between cold outdoor conditions and warm, dry indoor air. These temperature swings can be extra-irritating to vulnerable skin with a compromised barrier. It’s the same reason your hands get dry and your lips get chapped. 

Winter flare-ups are just one common example, but Research has found that any seasonal and environmental changes can possibly trigger your dandruff. It’s not just transitioning from the cold street to the heated office – it could be the hot, muggy street to the blasting AC, or the humid beach vacation to the dry airplane cabin [5]. The most frustrating part is that some scalps can tolerate such changes better than others. It’s a big spectrum and you’re somewhere on it! 

Hot & Humid

We’ve covered how low humidity can make your scalp vulnerable by increasing water loss from the skin barrier, but what about high humidity?

Studies such as this one which examined 166 subjects in Thailand for seasonal flare-ups found that hot weather and summer as triggers — almost the opposite of the classic winter pattern [6]. It turns out that warm, humid conditions are great for growing fungus in general, and make your scalp especially inviting to Malassezia. More humidity means more oil production & sweat buildup, and warm & damp conditions. Remember Malassezia is a fungus that eats your scalp oil – this means it has more to eat and ideal conditions to grow. Further, people are more likely to be outside for extended periods in the warmer months, often wearing headware. Hats, bike helmets etc. can exacerbate dandruff growth by amplifying sweat & oil buildup, and generally turning up the heat & humidity on your scalp [1,2]. 

Your hair routine can change with the seasons!

During Cold, Dry Weather Focus on protecting the scalp barrier.Avoid extremely hot showers and excessive use of harsh products. Use an ultra-gentle, anti-fungal shampoo like  Structure of Skin as often as you need to stay clean and flake free, but no more than that! 

During Hot, Humid Weather Pay more attention to sweat, oil, and buildup. Wash after heavy sweating, or long periods under a hat or helmet. An ultra-gentle shampoo like ours is your friend during the warmer months too if you are constantly sweating and/or wearing headwear, since you can use it as often as you need it, even if that’s twice a day! 

References

1. Borda LJ, Wikramanayake TC. Seborrheic Dermatitis and Dandruff: A Comprehensive Review. J Clin Investig Dermatol. 2015;3(2). doi:10.13188/2373-1044.1000019.

2. Leroy AK, de Almeida RFC, Obadia DL, Frattini S, Melo DF. Scalp Seborrheic Dermatitis: What We Know So Far. Skin Appendage Disorders. 2023;9(3):160–164. doi:10.1159/000529854.

3. Ozkok Akbulut T, Suslu H, Atci T. Is the Frequency of Seborrheic Dermatitis Related to Climate Parameters? Sisli Etfal Hastan Tip Bul. 2022;56(1):91–95. doi:10.14744/SEMB.2021.67503. 

4. Green M, Kashetsky N, Feschuk A, Maibach HI. Transepidermal water loss (TEWL): Environment and pollution—A systematic review. Skin Health Dis. 2022;2(2). doi:10.1002/ski2.104. 

5. Turner GA, Hoptroff M, Harding CR. Stratum corneum dysfunction in dandruff. International Journal of Cosmetic Science. 

6. Araya M, Kulthanan K, Jiamton S. Clinical Characteristics and Quality of Life of Seborrheic Dermatitis Patients in a Tropical Country. Indian J Dermatol. 2015;60(5):519. doi:10.4103/0019-5154.164410. 

Additional clinical review: Dall'Oglio F, et al. An Overview of the Diagnosis and Management of Seborrheic Dermatitis.