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your scalp's itchy inflamed maybe
even raw and none of the products
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you've tried seem to be working and
now maybe your hair is even thinning
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here's the problem most scalp products aren't
treating the right cause and no one's really
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explaining what that is and a lot of scalp
products - well - they actually make things worse
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I'm Michelle chemistry PhD cosmetic science
nerd and I used to scratch my scalp raw
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it took me years of going through the research and
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trying different products before I
worked out what was really going on
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so in this video I'll break down the real science
behind itchy scalp and how to fix it for good
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there are three major causes of itchy scalp we
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need to understand and they all
need to be treated differently
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if you miss one, a product might work for a
while but then your scalp just gets itchy again
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cause one is microbes
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now you might be thinking "I've heard
malassezia yeast causes dandruff,
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but my scalp's just itchy - I don't have flakes."
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But this is still important it's one of the
most misunderstood causes of itchy scalp
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you see malassezia is on everyone's scalp
and this is a good thing when everything
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is balanced just don't think too
hard about all of those microbes
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it helps keep more harmful microbes in check
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but when things are out of balance when this
yeast overgrows that's when things go wrong
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the problem comes from malassezia
microbes interacting with sebum
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which are the oils naturally on your
scalp it feeds off this oil and turns
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it into a bunch of irritating substances
these make your scalp inflamed and itchy
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and this happens even if you
don't see any dandruff flakes
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in this study inflammatory markers rose after 3
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days and people reported itching but it
took 3 weeks to start seeing more flakes
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so a lot of people don't realize these
microbes are a big part of their problem
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this was me I was hovering in this
sort of itchy region but it wasn't
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quite at the flake stage so I thought
dandruff products just weren't for me
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and a lot of other scalp products actually feed
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this yeast so I was making things
worse without even realizing it
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but just tackling the microbes usually isn't
enough you also need to understand dry scalp
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your scalp is skin there's a whole bunch of hair
and extra oil but it still has the skin barrier
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structure and it's still more comfortable
when it's the right level of moisturized
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if you use really harsh products that
strip your scalp too much it can dry
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out and feel itchy and tight just
like the skin on your face and body
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if you're a skincare nerd you might
already know the wrong cleanser can
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really mess up your skin I talk about this
in my other videos and my skincare eBook
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from a formulation point of view a shampoo
is just a special type of cleanser if you
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use the wrong shampoo the cleaning
ingredients the surfactants they can
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stay in your scalp after rinsing and mess
up your barrier it gets leaky it lets out
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water more easily and it lets irritants
in more easily as well so you get itchy
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and some of your habits might dry it out
even more if you use really hot water in
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the shower or you use a really hot blow
dryer or if you just have really dry and
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cold weather and you use a heater
all of this can dry out your scalp
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hormones can also be a big part of this and
this can still be an issue if your scalp is oily
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you might have heard that oily skin can still
benefit from moisturizer if it's losing too
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much water you end up in this oily but dry
situation you have too much oil but that
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oil is not keeping the water in your skin the
exact same thing can happen with your scalp
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so you might already see the big problems we have
here if your scalp issues are caused by these
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dandruff microbes but you think it's dry scalp
then you might wash your hair less you might put
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oils on your scalp but these will actually make
the microbes grow more and your itching gets worse
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if you're using an anti-dandruff shampoo at the
same time it might seem like it's not helping and
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you give up on it thinking it might not be either
of these it might be some secret third issue
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foreshadowing
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so you really need to work out
which of these apply to you
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this microbe situation is more common and it's
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even more likely to be this if you've
ever had dandruff before about half
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the population is prone to dandruff and
we're more likely to have an itchy scalp
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also if your scalp and skin is generally oily
if you don't wash your hair that much if you
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live somewhere humid this is probably part of
your problem but if you've never had dandruff
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and none of your relatives have (genetic
susceptibility is a big part of dandruff)
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your skin is very dry you might even have eczema
and you wash and dry your hair regularly then you
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might be in the less common situation where
dry scalp is an issue but not the microbes
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but if you have this microbe situation you
probably also have dry scalp because these
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substances from the microbes they will actually
make your scalp barrier more leaky and a lot of
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dandruff treatments also dry out your scalp
so this becomes a bit of a vicious cycle
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I didn't really make this connection
until I got deep into researching my
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book The Science of Beauty if you're finding this
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video helpful check it out as well as
hair it covers skin nails and makeup
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luckily there are lots of products and tips that
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work for both of these without
making the other one worse
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but before we can talk about products we
need to look at the last piece of the puzzle:
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potential allergens because if you're allergic
to something that you're using you can still
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itch even when the other problems are
fixed and there is a really common
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allergen in shampoos and that is the main
product type for dealing with scalp issues
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here is a cosmetic chemist insider
tip: wash off products like shampoos
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they are formulated differently from
leave-on products wash off products
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don't stay on your skin for long so it's
safe to put higher levels of ingredients
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in them and this is generally fine except
for allergens if you're allergic to them
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I really need to stress this: if you aren't
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allergic to an ingredient
you do not need to avoid it
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allergies are when your immune system
overreacts to something that is normally safe
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I'm allergic to cats that doesn't
mean everyone needs to avoid cats
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but sometimes if your scalp is itchy
after you use particular products
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that can be a sign of an allergy
that you haven't discovered yet
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the two big ones are MI and MCI these
are even nicknamed "the itchy Ms" these
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are preservatives that became more
common after brands started getting
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rid of parabens because of misinterpreted research
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it was mostly for marketing purposes
but parabens are actually super safe
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very few people are allergic to them and
brands still needed preservatives because
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products will go moldy so MI and MCI started
getting more popular even though they weren't
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researched as much and it turns out a
lot more people are allergic to them
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when I looked this up in PubMed
I found 23 articles with the word
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"epidemic" in the title this is very
strong language for science papers
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these were suddenly the second
most common allergen after nickel
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again if you're not allergic these are
not a problem but it's estimated that
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at least a few % of the population
are allergic to these including me
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and the most annoying part these are really
common in scalp products it's gotten better
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but I found MI or MCI in all of these shampoos
specifically claiming to help itchy scalp so if
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you didn't know you were allergic these
might actually make your scalp itchier
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there's a related preservative that's super
common in liquid laundry detergents so if
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your clothes make you itchy sometimes there is
a good chance you're also allergic to MI and MCI
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here are some other common allergens if a lot of
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shampoos make you mysteriously itchy
you might want to look into these
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the most reliable way to check is patch
testing with a medical doctor but if you
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keep track of shampoos and products that do and
don't make you itchy you might see some patterns
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there are other causes but these
three are the most likely if itchy
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scalp is something you've had for a
long time and there's no rashes or
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other obvious things suddenly changing
if you do have those go see a doctor
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now that we know the big causes of itchy scalp and
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how to work out which ones you
have let's talk about fixing it
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first microbes here is the big
takeaway you don't need to have
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dandruff to benefit from anti-dandruff products
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I think a lot of people overlook them
because they don't have flakes and for
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some weird reason the sensitive scalp products
usually aren't near the anti-dandruff products
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there are four heavy-hitting ingredients that
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control malassezia and they're mostly
in shampoos as well as some serums
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disclaimer I've done sponsored posts in the
past for some of these products but I wasn't
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obliged to include them here I'm recommending
them because I genuinely think they're good
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selenium sulfide is orangey yellow and it smells a
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bit like rubber but it's very effective
some people don't mind the smell but my
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nose is super sensitive to sulfur
I worked with it a lot in the lab
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the best smelling ones I've tried are the Dercos
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anti-dandruff DS shampoos to me Selsun
Blue's fragrance is just a bit too strong
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zinc pyrithione is another big one Head
and Shoulders pioneered a lot of its use
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it works really well the main
downside is that it's insoluble
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the tiny particles can make
your hair feel a bit gritty
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it was recently banned in the
EU even though it was found to
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be safe at under 1% and that means that
it should still not be harmful at 100%
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I talk more about safety assessments in this video
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this is an EU regulations quirk
- ingredients that have specific
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health effects get banned just in case but
it is still available in other countries
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piroctone olamine is a newer ingredient that's
getting more popular and this one is really nice
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because it's soluble it doesn't smell so shampoos
with it look and feel just like normal shampoos
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I was actually using one for ages
without realizing the Essano Scalp
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Refresh and I was amazed that I could go
three days without feeling itchy usually
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it's just a day sometimes it's actually
less because my scalp is just super fussy
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piroctone olamine is in tons of shampoos
now you have a massive range of options
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I found it in so many scalp products
even some that didn't say dandruff
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the Head and Shoulders Bare range
might be a good option if you think
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you have an allergy these have less ingredients
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there's also ketoconazole this is antifungal
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and it's im Nizoral climbazole
is the weaker cosmetic version
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there are some malassezia species that
are resistant to it so if this isn't
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working for you maybe try one of the other actives
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also the other three are more
broadly antimicrobial so if you
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have say scalp acne those can also help with that
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some other ingredients for dandruff
aren't as effective for controlling
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malassezia but they can help with other
aspects like flakes or soothing your scalp
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look carefully at the ingredient
list to check what you're getting
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now some common mistakes with anti-dandruff
shampoos number one the microbes are on your
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scalp and mostly inside the hair follicles
so focus on massaging it all over your scalp
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number two follow the instructions on the
bottle there's a common myth that these
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shampoos work better if you leave them for a few
minutes but this only works for some shampoos
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other shampoos have the active ingredients in
little bubbles called coacervates they only
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release the actives when you dilute it when
you're rinsing so leaving these ones on your
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scalp for longer you might just be making
your scalp dry and itchy for no good reason
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if you use a conditioner on your scalp afterwards
you'll actually wash away some of the actives
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so either keep the conditioner under your ears
or condition with an anti-dandruff conditioner
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shampooing regularly usually works
better for itchy scalp if you're
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using anti-dandruff shampoo that means
you are putting more of the active onto
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your scalp but on top of that you're also
getting rid of the oils and the microbes
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you can also get anti-dandruff
ingredients in serums these are
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great between washes although they
don't really replace a proper wash
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most of these have piroctone olamine
there's also some with zinc pyrithione
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another thing worth thinking about if microbes are
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your problem is moisture this can make
it easier for the microbes to multiply
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it's a good idea to dry the hair around your scalp
faster use a hair dryer rather than leaving it to
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air dry especially if it's cold or humid but to
protect the scalp barrier don't have this too hot
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my hair dryer has a special scalp mode that's the
perfect temperature but hopefully your hair dryer
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has a setting that feels comfortable
if it's too hot move it further away
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hats and helmets can also trap moisture and
make things worse especially when you're
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sweaty try to have some air flow in there
and wash your hair soon after you sweat
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now on to some things for dry
scalp which are also important
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for microbes remember the microbes
produce irritants which lead to a
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leaky scalp barrier and this first point
is especially important gentle shampoo
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you want something that won't make your
scalp feel stripped because it's drying out
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your barrier it's also making it easier for these
irritating substances to get in and cause itching
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again like with your face skin you don't want
to use anything that's too harsh in general a
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slightly acidic skin friendly pH is better for
your scalp somewhere between like four and seven
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pH isn't that important for your
hair which is another whole mess
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we need to talk about in a different video
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also avoid using conditioner on your
scalp the surfactants and conditioners
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are actually more irritating than
the ones in shampoo the hair near
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your scalp is nice and undamaged
it doesn't really need conditioning
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antioxidants they're a really safe
option they're great for protecting
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against irritation and improving your scalp
condition and the way that these malassezia
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microbes make these irritating substances it's
through oxidation so they can also help with that
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some studies show antioxidants can reduce
hair shedding which makes a lot of sense
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your scalp is where your hair grows
and oxidative stress is thought to
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be a contributor to hair loss the Dercos
Serum 10 is the one I've used the most it
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has piroctone olamine as well as a bunch of
antioxidants and centella which is soothing
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I also really like this nozzle which makes it
super easy to apply and it doesn't leave any
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sort of stickiness or weighing down after
it dries I can't tell I've used anything
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there are tons of scalp products with antioxidants
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just make sure they don't have oils
in them if microbes are an issue
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your tap water can be a big issue in some places
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especially hard water this is when
there's metal ions dissolved in the
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water and you might be able to see chalky
water stains and buildup around your taps
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hard water can be really irritating it
can make your hair feel like there's a
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film on it some metal ions
can also speed up oxidation
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the best solution is a whole house
water softening system but there
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are also inline softeners you
can get just for your shower
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filters usually get rid of
chlorine but not hard water
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ions so make sure you check what
exactly the product is going to do
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there are some products you
really want to be careful
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with if microbes are part of your
problem and the main thing is oils
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most oils aren't actually that good
at sealing in water malassezia feed
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on oils and makes them grow faster and they
turn it into those irritating substances so
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I would recommend avoiding plant oils
in any sort of leave-on scalp products
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some people do find oils helpful but I think
it's mostly the massaging massaging anything
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can help get residue off the scalp especially
for people who use a lot of product and don't
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wash their hair that often if you're in this
category and you think you might have this
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microbe problem maybe try massaging a serum that
has anti-dandruff ingredients instead of an oil
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dry shampoo this can be helpful
for soaking up oil and removing
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some of those irritants but it can't
really replace actual shampoo a lot of
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people who are using dry shampoo should
really just be washing their hair more
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spraying a dry shampoo too close to your
scalp can also be drying and irritating
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scalp scrubs and brushes this is really personal
preference but I personally don't find them very
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helpful for my hair type and routine I find
it pretty hard to get the scrub through my
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hair I feel like it's mostly just scrubbing
my hair which is damage I don't really need
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I don't mind brushes but I have nails
and that just works much better for me
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chemical exfoliants is similar it might be
helpful if you have a lot of buildup but I
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wash my hair almost every day and I don't use much
product so that just hasn't made much difference
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if you've thought about trying rosemary oil I
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would recommend against it
this video has more on why
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if you're wondering about dry hair I have a video
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all about hair and hydration my
hair science playlist is here
00:16:01
let me know what else you're wondering
about see you in the next video
