How Long Does a Hair Growth Serum Take to Work?

Most answers to this question say three to six months and stop there. That range isn't wrong. On its own it's close to useless, because it doesn't tell you what the number is measuring, or what you should be watching while you wait.

The short version: three months of actual use is the earliest anything can be read, and the bottle in your hand is how you check whether three months of use has happened. What customers most often say they notice first is new baby hairs, somewhere in the second month. Hair looking thicker comes later.

I founded Chloeya and we make Alpha, a serum in this category. The timeline below is sourced, and I say so wherever the source is our own customers.

Jump to: The timeline · Where "three to six months" comes from · Judge it by the bottle · Why it runs longer for some · If you've seen nothing · What our own customers describe · Common questions · What it costs to find out

The timeline: three months of use, not three months of waiting

How fast hair grows and how long a follicle rests set the pace, and both of those are measured in months. A follicle is the small pocket in the scalp each hair grows out of.

So a visible change in how thick your hair looks takes months. Shedding moves earlier, which makes it the first signal. It is also the hardest to read, because it is something leaving rather than something arriving.

Which means there are two clocks here, not one. Three months of use answers shedding and new baby hairs. Density is a six month question, and reading it at three tells you less than it looks like it does.

Two things stretch or shorten the timeline for any individual: how consistently the serum actually gets applied, and whether iron and thyroid have been ruled out.

Read against our own reviews, the order runs like this. It is an order, not a schedule, and the dates move from person to person.

• Weeks one to twoSome people find the scalp itself feels better in this window. That is not evidence about growth. A scalp that turns sore, red or itchy after starting something new is a reason to stop and have it looked at.
• Weeks two to fourShedding is the first thing to move, and it moves in either direction. Some people notice less. For others it rises before it settles. Nothing visible yet, and nothing has had time to be.
• Weeks four to eightNew baby hairs, described most often along the hairline and the part line. This is what our customers mention more than anything else.
• Weeks eight to twelveHair starting to look thicker, or a part line that has narrowed. Around the end of a first 50ml. Customers describe this later than the baby hairs, and fewer describe it at all, so it is the last rung to judge rather than the first.
• After thatWhat customers describe from here builds slowly, and some describe it well past six months.

Why it takes months and not weeks

Every hair grows from its own follicle, and each follicle runs its own cycle independently of its neighbours. That's why hair doesn't all fall out at once.

Each hair spends years growing, a couple of weeks winding down, then around three months resting before it is released and a new one starts underneath. Two consequences follow, and they explain almost everything about the timeline.

A resting follicle can't be hurried into growing. It has to finish resting first, usually around three months. A large share of your follicles can go into rest together after a birth, an illness, a stretch of low iron or a hard few months.

And a new hair emerging is not a new hair you can see. Scalp hair grows around a centimetre a month, so a hair that starts today is a centimetre long at week four and three centimetres at month three.

Where "three to six months" comes from

The three-to-six-month figure gets repeated everywhere without a source. It is when the studies stopped and measured, and it is roughly the pace the cycle sets, which is probably why it stuck.

On our own evidence page, where each study is set out with its length and who took part, the published studies of the actives used in serums like this each ran twenty-four weeks, which is six months. The one shorter study ran twelve weeks, which is three. It is the weaker end of the range in every other way too: 26 men, no women, run by the company that makes the ingredient, and never published, so nobody independent has ever checked it. That is the whole of where the range comes from.

Studies behind a serum are shorter and smaller than studies behind a medicine, which is the honest reason the evidence here is thin.

When researchers stopped measuring and when results appear are different statements, and almost every page you'll read collapses them. How much those studies establish is a separate question, and the same page answers it plainly.

The first month

Not much that's visible. That isn't a failure, and it isn't a reason to change anything. It's what the growth cycle allows.

What often happens in the first few weeks is more shedding. That surprises people, and it's a common reason they stop early. It usually isn't damage. It is a set of resting follicles letting go at around the same time. If your scalp is sore, red or itchy, that is a different thing, and it is worth stopping and having it looked at.

We've covered what shedding after starting a serum usually means separately, including the red flags that mean it is time to see a doctor.

The useful thing to do in month one is set up the comparison you'll need later. Take a photograph of your part line, in the same light, before anything changes. It's the step most easily skipped. Without it, month four is a comparison against memory, and memory moves in both directions.

Month one to month three

Two things are worth watching in this window: shedding easing, and new hairs arriving. They are easy to confuse.

If you were shedding more than usual, watch for it easing back toward your own normal. Not zero. Some shedding every day is ordinary, and there is a normal range for it. What matters is the direction over a couple of weeks, relative to where you started.

What some people notice in this window is short, fine, upright hairs along the hairline and through the part line. Customers call them baby hairs, and not everyone sees them at this stage. They're easiest to see in bright indirect light, with the part pushed to the opposite side from usual.

A change in how thick the hair looks can show in this window, and in our reviews it is the people at the two to three month mark who start describing it. It is the sort of change you find by comparing two photographs from the same angle, which is what the month one photograph is for.

If you are at month three with baby hairs and no change in thickness, you are in the commonest position our reviews describe. Thickness at three months isn't the standard to hold yourself to.

Old hairs thicken faster than new ones grow

Hairs that were already on your head can thicken up, and that is what people are describing when they say the part line looks narrower at two or three months.

A hair starting from nothing is slower. It needs three to six months to get long enough to change how thick your hair looks. Before that it is a hair on your head that nobody can see.

So three months settles one question and leaves the other open. It is long enough to judge shedding and baby hairs. Density needs longer.

Judge it by the bottle, not the calendar

This is the part most articles get wrong.

Counting weeks from the day you ordered assumes the bottle arrived immediately and that you've applied it every day since. Neither is reliably true. Delivery takes days, people miss days, and two people who bought on the same date can be a month apart in doses actually applied.

How much of the bottle you've used is the better unit, because it measures how many doses have actually gone on your scalp. It's also something you can check by picking the bottle up.

A 50ml of ours runs most people two to three months, applied once daily to a part line or a crown. Cover more of the scalp, or apply it twice a day, and it goes faster. How much you use and how often will move that either way, which is exactly why the bottle is the better unit. Go by what is left in it, not by the date.

Three months of use is one 50ml for some people and about one and a half for others. Carrying it out to month four or six, which is what density needs, is two bottles or more.

Here is the same person read two ways.

If it's been four months since your order and you're still on your first half, the honest read isn't that it didn't work. It's that it hasn't been tried yet.

If you want a method for tracking it, the part line photograph and the wash test are both free and take a minute each. The wash test is keeping the gap between washes the same, collecting the hair that comes out, and photographing it. Both are set out step by step on the shedding page.

Why it runs longer for some people

Hair loss is rarely driven by one thing, and the parts a serum doesn't reach are often the parts setting the pace.

Where the thinning comes from an inherited sensitivity to a hormone called DHT, the process is ongoing. The timeline runs longer, because you're working against something continuous instead of recovering from a one-off event. It also changes what consistency is worth, because there is no point at which the cause stops. That is a reason to choose a routine you can actually keep up.

Some thinning follows a specific event: a birth, a fever, a surgery, months of eating too little, or a long stretch of real stress. Where that is the cause, recovery often runs on its own schedule, and the main job is not interrupting it.

Low iron can hold everything else back. The number to ask for is ferritin, which measures the iron your body holds in reserve. It is a different test from the iron level in your blood, and a normal result on one does not settle the other.

Ask for the number itself, not just whether it was normal. Where the cut-off sits for hair is still argued over, so the figure is worth knowing, and it is a question for your doctor rather than for us. The same goes for your thyroid, the gland in your neck that sets the pace for a lot of the body, hair included.

You don't have to do these in order. Nothing about a serum on the scalp interferes with a blood test, so starting one while you wait for the other is a reasonable way to run it.

It's worth being plain about who does what here. A serum goes on the scalp, and that is the whole of its reach. Iron, thyroid, sleep, recovery and what happened two or three months ago are yours, and they often set the pace. The scalp half is the one that can be built for, and building it well is the whole of what we do.

If you've seen nothing after three months

Three questions, in this order.

Is this something a serum can act on at all? Some kinds of hair loss need a doctor rather than a product: loss speeding up month on month, hair coming out in patches, a scalp that is sore, red or itchy, or shedding still running heavily at month four. The full list of when to see someone is on the shedding page.

Has anything else been ruled out? Ask about ferritin and thyroid, and think back to what was happening two to three months before the shedding started. If none of that has been looked at, a serum was never going to be the whole answer.

Has it actually been three months of use, or three months since it arrived? Check the bottle. In what customers tell us, it is a common explanation, and it is the most fixable of the three.

Then check the photographs rather than the mirror, side by side and in the same light. New hairs at this stage are fine and short, and memory is generous in both directions.

If shedding has eased or baby hairs have arrived and only density has not moved, three months has answered what three months can answer. Density is the slower clock. A follicle that was resting the week you began has to finish resting before it grows at all, which on the figures above puts its first countable hair past month four.

If the photographs show nothing at all, then shedding and new hairs have had their fair test and come back empty. That is real information. Hair loss is rarely one thing though, and people start from different places, so month four to six is where the test is complete enough to say it has not worked.

Three months is already enough for the other decision. A scalp that has not moved at all by now is worth a doctor's look rather than another product, and you will not arrive empty handed: dated photographs and a ruled-out list are two of the things a doctor will want, and they are hard to reconstruct afterwards.

If you decide to stop, the honest answer is short. Nobody has run that study on a cosmetic serum, so what follows is unknown in both directions. An inherited sensitivity to DHT does not go away, so nothing here is a course you finish: stop and the building stops, while the hair you have grown carries on in its own cycle. Come back later and the same three months and the same photographs are what will tell you, from a record you have already started. What is actually known about stopping a serum is set out separately.

What our own customers describe

What we can show you is not a trial. It is what customers describe in their own words, next to their own photographs, on our results page. Across those reviews the thing named most often is new baby hairs at the hairline.

Neither the growth cycle nor the studies above is evidence about any particular product, including ours. This is.

"I had menopausal hair loss that was making me distressed. [...] After 2 months of daily use, my hair feels and looks healthier and thicker now. My parting line and hair line is less obvious, though the crown is still work in progress."

Verified purchase, five stars, Singapore. Published anonymously.

For her, two months of daily use was one 50ml. The part line first and the crown still open is the order this page describes, in her words.

A different customer photographed the same window.

Mimi's part line, two months apart. Once daily, one 50ml, and she was starting her second bottle when she wrote.

Three caveats. She was also using a ketoconazole 1% shampoo and three others in rotation, a monthly scalp scrub and monthly microneedling, so this is not a clean test of one product. The two shots are in different light. And a widened part narrows more visibly than anywhere else on the head, which is why this page keeps telling you to photograph yours in the same light every time.

Both were inside their first three months when they wrote.

Take a look at Alpha

Common questions

Can I speed it up by applying more often?

Applying more often will not make a resting follicle start sooner. The cycle sets that, and no amount of product changes it. What customers who use it twice daily describe is more change inside the same three months, rather than change arriving earlier. Applying twice a day also goes through a bottle in about half the time, so three months at that rate is two or three bottles rather than one or two. It is a trade, not a free upgrade. Start with the directions on your own bottle and let consistency over the months do the rest.

Does it work faster on recent hair loss than on long-standing thinning?

Generally the more recent the change, the more there is still to work with. A follicle that has been shrinking for years is a harder case than one that has been resting for months. Where it has already been years, give it three months before you read anything and the full four to six before you settle it. Lower what you expect to see, not the length of the run.

My hair started falling out after having a baby. What is happening?

After a birth, a lot of hairs that paused during pregnancy are released at around the same time. That is usually a synchronised release, not the start of a thinning pattern, and it usually settles on its own. The main thing is not to read that recovery as a product working or failing. Where it doesn't settle, it is worth a doctor's look. If you're pregnant or breastfeeding, ask your doctor before starting anything on your scalp.

What if I miss days?

Missed days spread the same bottle over more calendar time. A few don't undo anything. A pattern of them means you're further from a fair test than the calendar suggests, and there is nothing to make up for. Pick the bottle up, see where you actually are, and count from there.

What it costs to find out, and where that leaves you

If you haven't started, take the photograph first, and give it three months of real use before you read anything into what you see.

If you have started, pick the bottle up and look at how much is actually gone. That is where you are, whatever the order confirmation says.

The evidence in this category is thin, and I built one anyway. Here is why. Alpha is a formulation decision and not a trial result, and the decision was this: several pathways at the follicle instead of one, because thinning in women is rarely one thing. In practice that means five patented actives, seventeen botanical extracts and a base built for absorption. What each one has been studied for, and how well, is set out ingredient by ingredient on the ingredients page.

The pass mark on this page is set out before you pay, so here is what meeting it costs. Ours comes in three sizes, and by the standard on this page only one of them runs a full test in a single order.

• 25ml, SGD 75Answers a smaller question first, which is how your scalp takes it. It is not a fair test by the standard above, and I won't pretend otherwise.
• 50ml, SGD 125Two to three months at once daily. Enough to read shedding and new hairs, and about half of what density needs. The commonest way to start, and the point to decide is when the bottle runs low.
• 2x50ml, SGD 225Four to six months at once daily, which is the full window this page describes. On subscription it is 20% off the first order and 10% after that, so the ongoing price is SGD 202.50, or about SGD 1.69 a day on the 2x50ml. The interval can be changed at any time from your account.

Prices here are in Singapore dollars. Outside Singapore the product page usually shows them converted.

If you want the whole window in one order, it is the 2x50ml. If you would rather read the first signals and decide from there, the 50ml is where most people start.

Choose your size

Three months of use, and photographs from the start. That is enough to judge shedding and new hairs. Density is a six month question, so give that one the longer run. It is the standard I hold Alpha to, and I would hold any serum to it.

Sources

The study durations on this page are drawn from our Redensyl page, where each study is traced to its primary source and labelled by publication status. The normal shedding range and the red-flag list are sourced on what that early shedding usually means. The order of what customers notice comes from our own published reviews, and not from a study.

Important: This article is for information and is not medical advice. It is not clinical opinion, and where the two differ, follow the doctor in front of you. Hair loss has many causes and several are better answered by a blood test than by a serum. If your hair is thinning suddenly, coming out in patches, or if your scalp is sore, red or itchy, see a doctor or a dermatologist.