You run a hand over your head and feel a soft fuzz that was not there last week. A few days later you can see it in the mirror: it is growing. But it has come in white, or it has come in curly on someone who has always had straight hair, or it has come in with a texture you do not recognise as yours.
And someone has already suggested, with the best of intentions, that all you need now is “a little something to straighten it out”.
This is the point where it is worth slowing down. The hair coming in is the only hair you have right now, and it is the newest and most fragile part of the whole process.
Why it all fell at once instead of gradually
Most of the hair loss that walks into a salon is gradual. This kind is not.
At any given moment, somewhere between 85% and 90% of the follicles on the scalp are in the growth phase, anagen. During that phase the cells in the follicle’s matrix divide rapidly, and rapid cell division is precisely what chemotherapy targets. That is why the loss is close to total and happens in a block, usually two to four weeks after the first cycle.
The technical name for this is anagen effluvium: the growth phase interrupted halfway through. It is different from telogen effluvium, the diffuse shedding that turns up weeks after surgery, anaemia or a major stress, where the hair completes its cycle before it falls.
The distinction matters for one practical reason: in most cases the follicle was not destroyed, it was silenced. When the stimulus stops, it starts producing again.
The new hair is new in shape and pigment, not only in length
Here is the part nobody explains clearly.
Curl is not a property of the hair strand. It is a property of the follicle. The shape of the bulb, and the asymmetry with which cells turn into keratin on one side versus the other, is what makes a strand grow out straight, wavy or coily. When a follicle’s matrix is rebuilt after an interruption, that asymmetry can re-establish itself differently for a while.
The result: straight hair that returns wavy, wavy hair that returns in tight curls. Patient groups have nicknamed them “chemo curls”, and the phenomenon has been described for decades.
Colour follows the same logic. The melanocytes in the bulb, which inject pigment into the strand as it forms, are also fast-dividing cells and were also hit. They tend to take longer to get back up to speed than the cells making keratin. That is why the first hair comes in white or grey for a lot of people: the hair factory has switched back on, the colour factory has not.
In most accounts, texture and colour drift back towards something close to the original over the first or second year. They do not always come back identical. The point is that at four months, you still do not know what your hair is.
What happens at each stage
Human hair grows at an average of roughly 1 cm a month, with real variation from person to person. The table below is a reference for pace, not a personal schedule.
| Since the last cycle | Average length | What is usually going on | What makes sense to do |
|---|---|---|---|
| 3 to 6 weeks | fuzz | first strands, many fine and without pigment | wash normally, protect from the sun |
| 2 to 4 months | 2 to 4 cm | visible coverage, texture still unstable, pigment starting | a first shaping cut, no chemical services |
| 6 to 12 months | 6 to 12 cm | texture settling, colour returning in bands | a structured cut, temporary colour if cleared |
| 12 to 24 months | over 12 cm | mature hair, you can start to see what is permanent | colour and texture decisions, with hair and scalp assessed |
Why early chemical services are the worst investment in the whole process
This is the thesis, and it stands on four legs.
First: you would be treating a temporary state. Straightening a texture at four months that may be something else at eighteen means spending the integrity of the hair on a target that is going to move. Hydroxide-based straighteners work above pH 12 and break bonds irreversibly. There is no undo.
Second: the chemistry acts on the entire strand. With 3 cm of hair there is no such thing as a root touch-up. The product covers the full length of the only hair you have, and that hair is the youngest and the finest you have ever produced.
Third: your scalp is not in its usual state. It may be dry, sensitive, flaking, and for anyone who had radiotherapy to the area there can be residual changes in the skin. A caustic product on a compromised barrier raises the chance of an irritant reaction, and an irritant reaction on a scalp that is rebuilding is exactly what you do not want.
Fourth: white hair does not take colour predictably. With no pigment of its own and the cuticle of a brand-new strand, absorption is uneven. The result comes out in bands, and correcting bands takes more chemistry.
Add to that what has nothing to do with hair: platelet counts, low neutrophils, a port or catheter, medication in progress. Any procedure that risks abrading the scalp needs clearance from the team looking after you. That is not salon paperwork, it is a condition.
What you can do now that genuinely changes how you look
A cut. Scissors do not alter structure. With 3 or 4 cm of hair, the difference between “hair growing back” and “short hair by choice” is almost entirely design: where the volume sits, how the outline relates to your face, what happens at the nape. It is the biggest return for the smallest risk in this whole stage.
Normal washing. A scalp in renewal produces sebum and flakes. Washing as often as you need to, with a light touch and no fingernails, is care, not aggression.
Non-oxidative colour, if your doctor clears it. Ammonia-free and peroxide-free toners, pure henna powder, root touch-up sprays: they deposit on the surface and do not restructure the strand. Ask first, with the product name in hand.
Sun protection on the scalp. Skin that has spent months covered and is suddenly getting direct sun burns easily. A scarf, a hat or sunscreen.
Watch the scarf and the wig. Clips, adhesive tape and tight elastic on the same line, every day, apply tension exactly at the hairline where the hair is finest. Move the anchor point around.
When it is a matter for a doctor, not a salon
Some signs call for a dermatologist, ideally with your oncologist in the loop:
- Six months after the end of treatment with no growth, or with growth that is
clearly patchy and partial. The literature describes this as permanent chemotherapy-induced alopecia, more often associated with taxanes and with the high-dose regimens used before bone marrow transplant.
- A smooth, shiny area with no visible pore: this can indicate a scarring
process, where the follicle has been replaced by fibrosis.
- Pain, persistent burning, pustules, crusting, a sore that does not heal.
- Shedding that starts again after it had stopped. Endocrine therapy (tamoxifen,
aromatase inhibitors) can keep diffuse thinning going on its own, and that often gets read as “the chemo never wore off”.
None of this is solved by a salon protocol. Hair therapy comes afterwards, or alongside, never instead of a diagnosis.
What trichoscopy shows at this stage
The trichoscope is a magnifying camera that projects your scalp onto a screen, with enough resolution to see the follicular opening, how many strands emerge from each unit, and how thick each one is.
At this specific stage, it answers three questions the mirror cannot:
- How many follicles are producing, and whether there are empty follicles with
no sign of fibrosis, which is a good sign.
- Whether average thickness is rising from one measurement to the next, which is
the real indicator of recovery, long before length shows it.
- Whether there is a second problem sitting on top: an androgenetic pattern that
has become obvious now, wig traction, dermatitis.
It is also what makes it possible to tell “this is taking time” apart from “this has stopped”. Those are different conversations, and they lead to different decisions.
If you would like to talk about your case
The trichoscope hair assessment at Nelblack, in Tatuapé (East Zone of São Paulo, a short walk from Carrão station and close to the Tatuapé metro area), is a guided assessment: you follow the image of your own scalp on the screen together with the professional, seeing what she sees, and the measurements are logged so a later assessment can be compared with this one. It costs R$200 (Brazilian reais) and is credited in full towards the protocol, if there is a protocol.
If there is a protocol, the number of sessions depends on what your scalp and hair need. We measure again during or at the last session and compare it with the image from the first day, at no extra cost.
Open Tuesday to Saturday, 9am to 6pm, by appointment. Tuesday is the day reserved for scalp therapy.
If you are in treatment or recently finished it, bring whatever guidance your medical team has given you. The assessment fits around that. It does not replace it.