Most people I speak to are looking for the single thing that went wrong. One product, one deficiency, one moment. But when I ask them to lay out their hair story year by year, the picture is never one event. It is a line that shifts slowly, and the causes in year three are rarely the causes in year one.
I'm Lynn Yap, a cosmetic chemist and the founder of CLYNN by Nature. I have spent over twenty years formulating hair care and I mix every one of our formulas myself. The most useful thing I can teach you is not a product recommendation. It is how to read your own hair across time, so that when it changes you know what changed with it.
The three numbers that matter more than any shampoo
Before we get to routines, there are three things your hair is reading all the time, whether you are thinking about them or not.
Iron and ferritin. Ferritin is your stored iron. It can sit in the low end of the normal range and still be too low for healthy hair growth, especially in women. If you have heavy periods, have recently given birth, or eat a mostly plant based diet, this is worth testing rather than guessing. Ask your GP for ferritin specifically, not just a full blood count.
Thyroid. Both an underactive and an overactive thyroid can thin the hair, and it usually shows up as diffuse thinning all over rather than one patch. It often comes with things you might have dismissed: feeling cold, tired, low mood, or a change in your cycle.
Vitamin D. Very common to be low in Australia, even in the sunny states, because we are sensible about sun protection. Low vitamin D is associated with shedding, and in some studies with slower regrowth.
None of these are shampoo problems. No bottle fixes a ferritin of 15. But all three set the ceiling on what any routine can do, so it is worth knowing your baseline once and revisiting it every year or two.
The seasons of hair
Hair thinning tends to arrive in recognisable phases. Knowing which one you are in stops you blaming the wrong thing.
The postpartum shed
Three to six months after birth, oestrogen drops and a large batch of hairs that were held in the growth phase all release at once. It is startling, it peaks, and then it recovers on its own. If you are in this phase, your job is not to fix it. It is to protect the scalp and the existing hair while it cycles back.
The recovery years
After the shed eases, many women assume they are back to normal. Often they are not quite. Density returns slowly, and the new hairs are shorter and finer for months. This is when gentle scalp care and consistency pay off most, because you are supporting regrowth rather than responding to a crisis.
The perimenopause drift
Somewhere in the forties, oestrogen starts to shift and the balance between oestrogen and androgens changes. Hair at the part and crown gets thinner and the texture gets drier. This is not the same as male pattern loss, but the androgens do matter, and it is the phase where a scalp tonic aimed at DHT becomes more useful than a purely moisturising routine.
The thyroid and iron years
These do not have a neat age. They can arrive at thirty or at fifty five, and they often arrive quietly alongside other symptoms you have already learned to ignore. If your hair changed and nothing obvious explains it, this is the first thing to rule out with a blood test, not the last.
What actually changes in your routine
Once you know your season, the adjustments are small. That is the point. You are not rebuilding your whole routine every two years.
If you are shedding from stress or postpartum: reduce friction. Gentler brushing, less heat, no tight styles. Keep the scalp clean and calm. A mild, sulfate free cleanser and a light, non greasy scalp oil are enough.
If you are in the perimenopause drift: support the scalp barrier and consider a DHT focused tonic. Hair is drier in this phase, so condition the lengths properly instead of over cleansing the scalp to compensate.
If you have a deficiency or a thyroid issue: treat the medical cause with your doctor first, then use your routine to support regrowth. Expect three to six months before you see a real change in density, because that is how long a hair takes to grow out of the follicle and become visible.
The one thing that does not change
Consistency. Hair grows about a centimetre a month. Any routine, natural or otherwise, needs a minimum of three months of regular use before you can honestly judge it. Most people give up at six weeks, right before the first new hairs would have been long enough to see.
If you want to know which season you are in and which routine fits it, the free Hair Analysis takes about two minutes and matches your cause to a specific routine. You can take the Hair Analysis, or read more about the causes and the routines we build for each one on our hair loss page.
One last thing, and I mean it kindly: if your shedding is sudden, patchy, or comes with scalp pain, itching or redness, see a doctor or a dermatologist. A cosmetic chemist can formulate a beautiful routine, but a blood test and a proper look at your scalp will answer questions no bottle can.
This article is general information, not medical advice. Please speak to your GP or a dermatologist about your own situation.
