How Long Do Hair Vitamins Take to Work?

People ask me this constantly, usually about three weeks in, usually with a slight edge of disappointment in the message. The honest answer is around three months before you'd see anything in your hair, and the reason has very little to do with what's in the jar. It has to do with how hair actually grows, which is slower and stranger than most of us realise.

Skin is quicker, usually four to six weeks. Nails land somewhere in the middle, around eight to twelve. But hair takes its time, and once you understand why, the waiting gets a lot easier to sit with.

Why the hair you can see can't change

Here's the bit that reframes everything. Underneath your scalp, inside each follicle, cells divide, fill up with keratin, and then die. That's not a malfunction, it's the whole design. What pushes out through the surface is the finished product, and it has no blood supply and no metabolism of its own.

So the hair you're looking at in the mirror was built months or even years ago, and nothing you eat or take can reach it now. That sounds like bad news, but it just moves the question somewhere more useful. The only place your nutrition can show up is in hair that hasn't been made yet, and right now that hair is roughly a millimetre long, sitting under your skin where you can't see it.

Which means checking the mirror on day twelve is really just a careful inspection of the past. Nothing has gone wrong. You're simply looking at the wrong part.

Not all of your follicles are working right now

Every follicle runs on its own schedule, and they're deliberately out of sync with each other. That's the only reason we have hair year-round rather than shedding it all at once, the way most mammals do.

There are three phases. Anagen is the growth phase, and it's the long one, lasting anywhere from two to seven years. Somewhere between eighty five and ninety percent of your hairs are in it at any given moment, and it's the only phase where nutrition has anywhere to go, because it's the only phase where hair is being built. Catagen is a brief transition of two or three weeks, when the follicle detaches from its blood supply and winds down. Only about one percent of hairs are here. Then there's telogen, the resting phase, where a finished hair sits in place for around three months before it sheds and the follicle starts again. Ten to fifteen percent of your hairs are resting at any time.

That last number explains something worth knowing, which is that losing fifty to a hundred hairs a day is completely normal. It's just the resting phase finishing on schedule, and it has nothing to do with whatever you've started taking. People sometimes panic about this in the first few weeks and stop, which is a shame. If your shedding is sudden or unusually heavy, though, that's worth a GP visit rather than a change of supplement.

It also explains why the timeline stretches. If a follicle happened to be resting on the morning you started, it won't begin building anything new for up to three months, and only then does the hair need to grow out far enough to see. So it isn't three months for all of your hair. It's three months for the hairs that were already growing, and longer for the ones that were taking a break.

You're probably watching the wrong end

Almost everyone looks for length, and length is genuinely the last thing to change. The first real difference appears at the root, as a few centimetres of new growth that behaves a little differently to the rest of the strand.

Most people never notice this on purpose. They notice it months later, as a vague sense that their hair sits differently now, and if you asked them when it started they honestly couldn't say. It's also why photos are fairly useless at week six but quite revealing at month four, because what you're really photographing is a boundary moving slowly down the strand.

Skin, nails and hair run on different clocks

This is the table I wish someone had shown me years ago, because it takes most of the anxiety out of the process.

Skin renews fastest, so if anything shifts, that's usually where it shows first. Nails are the most straightforward of the three to read, because a nail is an uninterrupted record of the last several months, growing out from the base at a steady, measurable rate. If you want an early honest signal, watch your nails rather than your hair.

Hair comes last, always. So when you see a product promising visible hair results in a fortnight, it's worth remembering that the biology simply doesn't allow for it.

What the first six months actually look like

For the first month, realistically, nothing. That's the correct outcome rather than a disappointing one, and it's also the point where most people give up. There's no evidence to find yet, so if you go looking you won't find any, and then you'll draw a conclusion that feels perfectly reasonable and happens to be wrong.

Between weeks four and eight, skin tends to be the first place anything appears. Your nails will have grown three to six millimetres of new plate by then, but the older plate is still most of what's on your finger, so it's hidden.

Months three and four are the real window. By then you've got three or four centimetres of hair that grew during the change, and your nail is more than half new material. If you took a photo on day one, this is the moment for the second one. And by month six, every fingernail you're looking at grew after you started, with around six centimetres of new hair, which is finally enough to be part of what people actually see.

What a label is allowed to say, and why it matters

Authorised nutrition claims in the UK are maintenance claims, which means they describe keeping normal function working normally. They sound underwhelming next to the rest of the category, and that's rather the point. They're written to match the evidence.

Here's the authorised wording for our Beauty gummy:

• Biotin contributes to the maintenance of normal hair and skin.
• Zinc and selenium contribute to the maintenance of normal hair and nails.
• Vitamin C, A and biotin contribute to normal collagen formation for the normal function of skin.
• Zinc and iodine contribute to the maintenance of normal skin.

Read that list again and notice what isn't in it. Biotin carries no authorised claim for nails, despite biotin being sold for nails on more or less every shelf in the country. Nails come from zinc and selenium.

I mention this not to score points off anyone, but because it's a genuinely useful thing to know when you're standing in an aisle comparing jars. If a label pairs biotin with a picture of a fingernail, it tells you something about how closely the rest of it has been checked.

It's also worth saying that biotin deficiency is uncommon in people eating a varied diet. Maintenance of what's normal is a smaller promise than this category usually makes, and it's the one that stands up.

One thing to mention to your GP

This comes up rarely and matters more than most people expect. If you have blood tests booked, tell whoever takes them that you're taking a supplement containing biotin.

Biotin at higher intakes can interfere with certain lab assays, including some thyroid and cardiac ones, and it can shift the reading in either direction. It isn't doing anything to you. It's affecting the measurement, which is arguably the bigger problem, because that measurement is what a clinical decision gets made from. One sentence to the nurse sorts it out completely, and almost nobody thinks to say it.

We've all been trained by an industry that delivers in two days to expect that anything worth having turns up on a schedule we set. Hair doesn't work like that. It grows at roughly a centimetre a month whether you're watching closely or not, and whether you spent a lot or a little.

So the only real variable in your control is whether you're still going in three months. That's it. And it makes this less a question about supplements than about how comfortable you are in the gap between doing something and seeing something. Most people find that gap hard, so they change course around week three, which resets the clock and leaves them no wiser than when they started.

If you're going to try something, give it a full cycle before you judge it. Not because patience is a virtue, but because three months is simply how long it takes for the answer to become visible.