We’ve spent the last few years hearing all about our gut microbiome.

Then skincare decided to get involved.

And now, apparently, it’s our scalp’s turn to get on the biome boat.

Prebiotic shampoos, scalp serums and “microbiome-friendly” hair products are popping up everywhere. And if you've recently stood in the shampoo aisle wondering when washing your hair became quite so scientific, you're not alone.

The theory sounds convincing enough. Look after the community of microorganisms living on your scalp, and you create a happier environment for your hair to grow in. So how much of it is actually backed by science?

Yes, there are bacteria living in your hair

Quite a lot of them!

Your scalp is skin, and just like the skin everywhere else on your body, it's naturally home to bacteria and fungi.

Some of the regulars include Cutibacterium and Staphylococcus, alongside fungi such as Malassezia.

Not necessarily something you want to picture while massaging in your shampoo in the morning.

But they aren't there because your hair is dirty. They're a normal part of the scalp environment.

What researchers are more interested in is the mix of microorganisms living there and what happens when that changes.

And dandruff gives us a pretty good example.

Your dandruff probably isn’t because you need to wash your hair more

A flaky scalp can make you feel like you need to scrub your hair within an inch of its life.

Dandruff, however, is more complicated than simply having a dirty or dry scalp.

Research has found that people with dandruff can have a different mix of bacteria and fungi living on their scalp compared with people without it.

One of the most studied is Malassezia, a yeast that naturally lives on our skin but has also been linked with dandruff.

The important thing is that these microorganisms aren’t necessarily the problem themselves. They’re supposed to be there.

It’s changes in the overall scalp environment that researchers are interested in.

So rather than just reaching for that infamous 2-in-1 and getting a good scrub on, there may be a little more going on behind those flakes.

A shampoo study gives us a clue - but not an answer

One recent study followed 41 people with oily dandruff for 28 days.

Participants used a shampoo containing piritonolamine three times a week. By the end of the study, their dandruff symptoms had improved.

When the researchers analysed their scalps, something else had changed too: the bacterial and fungal communities.

That's interesting because it suggests improvements in dandruff can happen alongside changes in the scalp microbiome.

What it doesn't prove is that changing the microbiome was responsible for clearing the dandruff.

There were only 41 participants, the study lasted four weeks, and there wasn't a separate control group (which every science buff will tell you isn't fab).

So it's a useful piece of the puzzle rather than proof that we should all be shopping for microbiome-balancing shampoo.

And that brings us rather conveniently to our high street beauty aisle.

What does “microbiome balancing” even mean?

This is where the science and the label on your shampoo bottle don't always match up.

You'll see products claiming to support, feed, protect, or balance your scalp microbiome.

The problem with that?

We don't currently have one agreed definition of a perfectly “balanced” scalp microbiome.

Same with our gut, our scalps aren't identical. Someone whose roots are oily again approximately six minutes after washing them isn't necessarily going to have exactly the same scalp environment as someone confidently strolling into day five.

Age, sex, sebum levels, and other individual factors can all be associated with differences in the scalp's microbial community.

So, whilst the microbiome is real.

The idea that every scalp needs to reach the same perfect microbial balance?

That's where we should be a little more sceptical.

Hair loss is where the claims get trickier

Now, this is probably the bit most of us want to know about.

Could our scalp microbiome have something to do with hair loss?

Possibly, but its early days.

Researchers have found differences in the scalp microbiomes of people with certain types of hair loss, including androgenetic alopecia.

But that doesn’t mean the microbiome is causing it.

We don’t know yet whether these changes contribute to hair loss, happen because of it, or whether there’s a bit of both going on.

And let’s not forget, hair shedding can happen for all sorts of reasons. Stress, hormones, genetics, illness and nutritional deficiencies can all play a part.

So if you’re suddenly finding a lot more hair in your shower, I wouldn’t rush out and buy something promising to “rebalance” your scalp.

Finding out why you’re shedding in the first place is probably a much better place to start.

Do we really need a skincare routine for our scalp?

After years of cleansers, toners, serums, acids, masks and moisturisers, you might be wondering whether your scalp now needs its own 10-step routine.

Thankfully, no. At least, the current research doesn't give us a reason to think it does.

But the trend does make a good point.

We spend loads of time thinking about our hair. Is it dry? Frizzy? Thinning? Why did it look absolutely amazing yesterday and horrendous today?

Meanwhile, we barely think about the skin underneath until it starts itching or flaking.

You don’t need to know exactly which bacteria or fungi are living between your roots. But it is worth noticing when something changes.

Persistent itching, flaking, soreness or unusual hair shedding shouldn’t just be covered up with another product.

And if the problem keeps coming back, shampoo number six probably isn’t the answer.

References

• Markos, S. et al. (2026) ‘Clinical improvement and scalp microbiome restructuring following a 28-day piroctone olamine shampoo intervention’, International Journal of Cosmetic Science.
• Malas, J. et al. (2026) ‘Scalp microbiome differences in subjects with self-reported hair loss: A quantitative approach to microbial dysbiosis’, International Journal of Cosmetic Science.
• Wang, X. et al. (2025) ‘Microbial dysbiosis and its diagnostic potential in androgenetic alopecia: insights from multi-kingdom sequencing and machine learning’, mSystems.
• Xu, Y-N. et al. (2025) ‘Dandruff scalp microbiome exhibits flake severity and sex-related differences’, British Journal of Dermatology.
• Tao, R. et al. (2021) ‘Skin microbiome alterations in seborrheic dermatitis and dandruff: A systematic review’, Experimental Dermatology.
• Saxena, R. et al. (2018) ‘The diversity and abundance of fungi and bacteria on the healthy and dandruff affected human scalp’, PLOS ONE.