Malassezia Risk Index (мж) - a formula to estimate how yummy your skincare looks to malassezia / seborrhoeic dermatitis

I’ve had real baffling problems with skin sensitivity, dryness and flare-ups all my life (i’ve seriously been told by a doctor that i may just have a slight skin allergy to water), but after moving from Malaysia to the UK, my dermis seemed to face a whole crisis., i presume because of the low temp and humidity combo., but also because I was facing a feedback loop of overapplying lotion hoping it would make the dryness go away, only for it to make it worse. after reading the malassezia bible, it seems the problem has been the products themselves feeding what is basically this fungus that has colonized my face. since them, i’ve been obsessively researching every ingredient off all my skin products, and its been a struggle to say the least, just because there’s so much to avoid! but i’ve found a pretty decent way of estimating the risk of each skin product i’m using.

a more sensible human being would’ve just used sezia.co but basically, i just ask gibbidy to list ingredients in the list that are in the C11-C24 range, or any ingredients of concern, and to weight them by the position in the list (ingredients need to be order ofc) using the formula:

мж% = 1/Position x 100

so if there is a product with 1 fatty acid and nothing else мж% = 1/1 = 100%. the index also punishes the number of risky ingredients by stacking them up - because everyone needs a varied diet! so if the product is nothing but 2 fatty acids мж% = 1/1 + 1/2 x 100 = 150%, or if its 3 then мж% = 1/1 + 1/2 + 1/3 x 100 = 183%.

doing this you get an easily interpretable single number that should estimate how hungry it’ll make your malassezia. it’s quite flawed like any metric that aims to flatten the complexities of the world into a single number, but it helps to keep track of the risks of my entire pile of face food. i call it my Malassezia Risk Index (мж) with a cool made up mathmatical symbol.

it’s also important to consider the risk or fatty acid content of the ingredient as not all are 100%.

here are some examples of some sunscreens i’ve run through this formula:

Aveeno Calm + Restore Daily Moisturizer Mineral Sunscreen With Broad Spectrum SPF 30:

• Glyceryl Stearate: 1/71
• PEG-100 Stearate: 1/9
• Polyhydroxystearic Acid: 1/10
• VP/Hexadecene Copolymer: 1/11
• Cetearyl Olivate: 1/16
• Sorbitan Olivate: 1/17
• Stearic Acid: 1/18
• Cetearyl Alcohol: 1/23

= 67мж%

Avene Mineral Fluid Spf 50

• Isocetyl Stearoyl Stearate: 1/5
• Isopropyl Palmitate: 1/6
• Isododecane: 1/8
• Isohexadecane: 1/9
• PEG-30 Dipolyhydroxystearate: 1/13
• Stearic Acid: 1/15
• Glyceryl Behenate: 1/23
• Glyceryl Dibehenate: 1/24
• Helianthus Annuus (Sunflower) Seed Oil: 1/25
• Tribehenin: 1/31

= 90мж%

Bondi Sands SPF 50+ Mineral Face Fluid

• Isododecane: 1/3
• PEG-30 Dipolyhydroxystearate: 1/5
• C18-36 Acid Triglyceride: 1/10
• Polyglyceryl-3 Diisostearate: 1/12
• VP/Eicosene Copolymer: 1/13
• Stearic Acid: 1/16
• Polyhydroxystearic Acid: 1/17

= 91мж%

it’s not perfect because there’s no way of knowing actual weightages of every ingredient of every skincare product, but i think it might be the best i can do with what we have., and not all fatty acids are equally harmful. back when i put these through The Machine, the LLMs would sometimes miss certain ones (not surprising as they can’t count the number of Rs in words without “thinking”), but nowadays they seems much more capable.

here are some more results:

E45 Psoriasis Cream: 73мж%

E45 Itch Relief Gel: 0мж%

AVEENO BABY DERMEXA EMOLLIENT CREAM: 60мж% (this ones kinda interesting cuz it’s petrolatum content was a big part of this one, in the blog the verdict on vaseline seems to be undetermined but gpt claims “Its chemical composition can vary, but it generally falls within the C15-C30 range”)

Aveeno Face CALM+RESTORE® Gentle PHA Exfoliating Cleanser: 101мж% (you’re supposed to wash it off but i’m guessing a lot of it still sticks around after you do, I’ve found this one to be a massive trigger on my skin)

CeraVe Resurfacing Retinol Serum: 42мж%

CeraVe Facial Moisturising Lotion SPF50: 69мж%

Simple Protect ‘N’ Glow Radiance Booster Spf30: 243мж% (by far the highest i’ve tested so far, seems to be like 95% of pure malassezia food. i was quick to blame this one for getting my seborrhoeic dermatitis out of control but in context of the product (you’re only supposed to use 4 drops) its probably not as harmful to use as the number suggests, though still a terrible idea to use it if you have any malassezia related problem and it did make me flare up very often)

JOHNSON’S® Bedtime Bath: 147мж% (now this one genuinely shocked me. its the first soap i’ve tested. upon further inspection, all ingredients “contain C12-C18 fatty acids” but in a lot of cases, relatively low amounts, maybe its a good idea to ask gpt to evaluate the amount of fatty acids contained, if its just in low amounts, it should be weighted down like 1/3, or if it contains fatty acids but the ingredient itself isnt a fatty acid, then it can be weighted down like 2/3. etc. when asking gpt to adjust for this the new result is 96мж%, which is still really high. i’ve found that many products that are meant for sensitive skin are actually devastating to my skin.)

[update]

the last 2 years I have essentially been using a combo of manuka honey (0мж% obviously) for its anti-fungal properties alongside the E45 Itch Relief Gel (0мж%) previously mentioned and as a cleanser I use a ketoconazole shampoo. i also used to use the famous De La Cruz 10% Sulfur. it seemed to work but it really sucked when it got in my eyes and while i didnt mind the smell my partner did. after a few months of basically figuring everything out it basically completely went away, but over the years I’ve loosened my grip and started experimenting too much with whatever i have access to or whatevers trending (bad idea), which has now lead me back to evaluating my entire regimen again… red faced. I’ve also been experimenting with red light therapy which seems to be harmless. i think i purchased a lamp way back when people were unironically using it on their balls which i thought was hilarious until i actually did some research which then brainwashed me into believing it could untwink me or something. anyway heres a list of some products of note.

Beauty Of Joseon Calming Serum Green Tea: 0мж% (antioxidants in green tea apparently compliment red light therapy, it also contains Coptis Japonica Root which is supposedly antifungal)

INNISFREE Green Tea Hyaluronic Skin: 0мж% (cheaper green tea solution with exfoliating PHA properties)

BIORE UV Milk Spf50+: 18мж%? (sunscreen has been the biggest pain. this one was actually recommended in the original blog i mentioned at the start. on the blog they state it had been reformulated to include stearic acid? ingredient lists seem to vary online, but i can confirm the blog’s claims now for the blue, white and pink bottles i checked in person. the ingredients list of the new orange bottle “colour correct” online are all lying. from blurry videos from reviews online you can spot stearic acid etc.)

Skin Aqua Super Moisture Milk SPF 50+: 0мж%? (Lauryl- ingredients could break down into a C12, but otherwise it looks like a great option. problem is it is hard to find, it seems its been discontinued? and the “mild milk” “gel” and “essence” ones both have baddies.)

Nivea Super Water Gel Sunscreen SPF50: 0мж%? (this one was also mentioned in the blog. it also has a Lauryl- ingredient, but it seems like a non-issue. i used up an entire… i want to say bottle but in the UK i could only find the refill package which was just super annoying. my ex loved it even though he’d always put way too much on. it seems like the only asian skincare classics left, and the only place they stock it on shelves is in japan)

COSRX Ultra-Light Invisible Sunscreen: 0мж%

SUN BUM Kids SPF 50 Clear Sunscreen Face Stick: 0мж%

Hada Labo Uv Perfect Gel Spf50+ Pa++++: 0мж% (yes it is good.)

Cetaphil Sheer Mineral Liquid Sunscreen: 0мж%?

SUNPLAY Skin Aqua Tone Up UV Essence: 18мж%

SUNPLAY Sport Sunscreen: 25мж% (used to be my go to because it was just so easy to reapply even on wet skin but it seems i cant tolerate it anymore)

L’OREAL UV Defender Sunscreen: 25мж% (mum gave me this one to see if it’d help. it didnt really. sorry mum)

Biore UV Aqua Rich Water Essence (UK formula): 63мж% (none of it’s ingredients are in the worst-case C11–C14 zone so i find this one surprisingly tolerable if there’s really nothing else i can get my hands on)

Mary&May Retinol 0.1% Bakuchiol Cica Serum: 46мж% (i kept using it because it smelled so good but it def does cause problems over time)

La Roche-Posay Effaclar Adapalene Gel 0.1% Retinoid: 0мж%

Eau Thermale Avene Cleansing Foam Face Wash: 0мж%

The Ordinary 100% Plant-Derived Squalane: 0мж% (really great but does not agree with the honey and piles)

The Ordinary Niacinamide 10% + Zinc 1%: 0мж%

The Ordinary Multi-Antioxidant Radiance Serum: 0мж% (saw myself in the mirror after using this and scared myself lowk. i look great.)

The Ordinary Sulfur 10% Powder-to-cream Concentrate: 0мж% (because it’s intended to use as a spot treatment i just dilute it and mix it in to whatever serum or lotion im using)

De La Cruz 10% Sulfur: 0мж%