Hair Loss: Causes, Proven Treatments and How to Keep Your Hair Stronger

Short answer: most hair loss comes down to genetics (pattern hair loss), a stress-triggered shedding phase called telogen effluvium, or a nutritional or hormonal gap. The treatments with the best evidence are minoxidil, finasteride (for men), and to a lesser degree red light therapy and PRP. The earlier you start, the more hair you keep.

If you’ve started noticing more hair on your pillow or a part line that looks wider than it used to, you’re not imagining it, and you’re definitely not alone. By age 50, roughly half of men and a large share of women have visible thinning. The upside is that hair loss is one of the better-studied areas in dermatology. We know what causes it, and we know what works.

Below is a plain-English breakdown of why hair falls out, which treatments are worth your money, and the daily habits that quietly make a difference.

Key takeaways

• Losing 50 to 100 hairs a day is normal. A sudden jump, a widening part or a receding hairline is not.
• Pattern hair loss is driven by genes and sensitivity to DHT, a hormone made from testosterone.
• Minoxidil and finasteride have the strongest evidence. Both need 3 to 6 months before you can judge results.
• Low iron, vitamin D, zinc or protein can all make thinning worse, so get bloods checked rather than guessing.
• Sudden or patchy loss needs a doctor, not a supplement.

How the hair growth cycle works

Every follicle on your scalp runs on a loop. There’s a long growth phase (anagen) that can last several years, a short transition phase (catagen), and a resting phase (telogen) of around three months before the old hair sheds and a new one takes its place.

At any given time, around 85 to 90% of your hair should be growing. Hair loss shows up when something shortens the growth phase, pushes too many follicles into rest at once, or shrinks the follicles so new hairs come back thinner.

What causes hair loss?

Androgenetic alopecia (pattern hair loss)

This is the big one, in both men and women. Follicles that are genetically sensitive to DHT slowly shrink, a process called miniaturisation. Each new hair grows back a little finer and a little shorter until some follicles stop producing visible hair at all. In men it usually shows up at the temples and crown. In women it tends to look like a widening part and overall thinning on top.

Telogen effluvium (stress shedding)

A big shock to the system, like a high fever, surgery, childbirth, crash dieting or a rough emotional patch, can push a large number of follicles into the resting phase at the same time. The catch is the delay: the shedding usually starts two to three months after the event, which is why people rarely connect the two. The good news is it’s usually temporary and recovers within six to nine months once the trigger is gone.

Nutritional gaps

Hair follicles are some of the fastest-dividing cells in the body, so they’re among the first to feel it when you’re short on fuel. Low iron (ferritin), vitamin D, zinc and simply not eating enough protein are all linked with thinning.

Thyroid and hormonal changes

An under- or overactive thyroid, menopause, PCOS and some medications can all disrupt the hair cycle. If your thinning comes with fatigue, weight changes or feeling cold all the time, it’s worth asking your GP about a thyroid test.

Alopecia areata

This is an autoimmune condition where the immune system attacks hair follicles, leaving smooth, round bald patches. It needs a proper medical assessment, and there are newer prescription options available for more severe cases.

Traction and styling damage

Tight ponytails, braids, extensions, daily high heat and repeated bleaching can break the hair shaft or, over time, damage the follicle itself. Caught early, traction hair loss is reversible. Left for years, it can become permanent.

Hair loss treatments that actually work

Minoxidil

Topical minoxidil (5% foam or solution) is approved for pattern hair loss in both men and women. It extends the growth phase and can thicken existing hairs. Two things to know before you start: you need to use it consistently, every day, and many people notice extra shedding in the first few weeks. That’s a sign old hairs are being pushed out to make way for new growth, not a sign it’s failing.

Low-dose oral minoxidil has also become popular with dermatologists in recent years. It’s prescription-only and used off-label, so it’s a conversation for your doctor.

Finasteride and other DHT blockers

For men with pattern hair loss, finasteride lowers the conversion of testosterone into DHT. In clinical trials, most men who took it either stopped losing hair or regrew some. It’s a prescription medication and can cause side effects in a small number of users, so talk it through with your doctor. It isn’t suitable for women who are pregnant or could become pregnant.

Low-level laser (red light) therapy

Some red light caps, helmets and combs are cleared by regulators for pattern hair loss. Studies show modest gains in hair density for some people. It works best as an add-on to minoxidil rather than a stand-alone fix.

PRP (platelet-rich plasma)

PRP involves drawing a little of your own blood, concentrating the platelets and injecting them into the scalp. Early research looks promising, but treatment protocols vary a lot between clinics and it isn’t cheap. Think of it as a second step once the basics are in place.

Daily habits that support healthier hair

• Eat enough protein. Hair is made of keratin, which is a protein. Aim for a decent source at every meal.
• Check your iron, vitamin D and zinc. Ask for a blood test before you supplement. Topping up a real deficiency helps. Taking extra when you’re already fine doesn’t.
• Look after your sleep and stress. Chronic stress and poor sleep can tip more follicles into the resting phase. Our guide to biohacking your sleep has nine practical fixes.
• Go easy on your hair. Turn the heat down, loosen tight styles and space out chemical treatments.
• Try a ketoconazole shampoo. Some studies suggest it can support pattern hair loss treatment, possibly by calming scalp inflammation. Two or three times a week is plenty.
• Skip mega-dose biotin. It only helps if you’re deficient, which is rare, and high doses can throw off some blood tests, including thyroid and heart markers.

If you’d rather start with lower-risk options at home, we’ve looked at the research on rosemary oil, scalp massage and more in natural remedies for hair loss.

Watch: the science of hair loss and regrowth

In this Huberman Lab episode, Dr Andrew Huberman walks through the biology of the hair cycle and which treatments have the strongest evidence behind them.

When to see a doctor

Book in with your GP or a dermatologist if your hair loss:

• Comes on suddenly or falls out in clumps
• Shows up as round, smooth patches
• Comes with scalp pain, burning, redness or scaling
• Appears alongside other symptoms like fatigue, weight changes or irregular periods

Getting the cause right matters, because the best treatment for stress shedding is very different from the best treatment for pattern loss or alopecia areata.

Frequently asked questions

How much hair loss is normal per day?

Shedding 50 to 100 hairs a day is normal and part of the regular hair cycle. You’ll often notice more on wash days because loose hairs collect between washes. It’s worth paying attention if shedding clearly increases for several weeks or you can see more scalp than before.

Can hair grow back after hair loss?

Often, yes. Stress-related shedding usually recovers on its own within six to nine months. Pattern hair loss can be slowed or partly reversed with treatments like minoxidil and finasteride, especially when started early, while follicles are still alive.

How long does minoxidil take to work?

Most people need three to six months of daily use to see a difference, and up to a year for full results. A temporary increase in shedding in the first few weeks is common and usually settles.

Does stress cause hair loss?

Yes. A major physical or emotional stressor can trigger telogen effluvium, a diffuse shedding that typically starts two to three months later. It’s usually temporary once the stress passes.

What vitamin deficiency causes hair loss?

Low iron (ferritin) is the most common nutritional link, followed by vitamin D and zinc. Low protein intake can also cause thinning. A simple blood test can tell you whether any of these apply to you.

The bottom line

Hair loss is rarely a lost cause if you deal with it early. Start with the basics (enough protein, decent sleep, gentle hair care), get any deficiencies checked, and talk to a professional about proven treatments like minoxidil. Then give it time. Hair grows slowly, and judging any treatment before the three-month mark will only frustrate you.

Want more? Browse our Hair section for more evidence-based guides.

This article is for general education only and is not medical advice. Speak with your doctor or a qualified health professional before starting any new treatment, medication or supplement.