Seasonal Hair Loss: Why You Shed More in Autumn

If you notice more hair in the shower drain around March and April, you are not imagining it. Seasonal variation in shedding is well documented, and autumn is when most people notice it.

It is also, in most cases, temporary. Understanding what is happening makes it easier to tell apart from the kind of hair loss that does not reverse on its own.

First, what normal shedding looks like

Every hair follicle on your scalp runs through a cycle independently of the others. It grows for several years, briefly transitions, then rests before releasing the hair and starting again.

Because follicles are not synchronised, you shed continuously rather than all at once. Losing somewhere in the range of 50 to 100 hairs a day is unremarkable, and most people never notice it.

What makes seasonal shedding noticeable is that the proportion of follicles in the resting phase shifts, so more hairs are released over a compressed period.

More on the underlying mechanism in the hair growth cycle explained.

Why autumn

The prevailing explanation relates to the protective function of scalp hair.

Over summer, a larger proportion of follicles remain in the growth phase, which has been interpreted as an adaptive response: more hair coverage during the months of greatest ultraviolet exposure. As that need reduces heading into cooler months, a larger proportion of follicles enter the resting phase together, and the shedding that follows becomes noticeable some weeks later.

Studies examining seasonal variation in telogen rates have found the proportion of resting follicles peaks around the end of summer, with the corresponding shed following in autumn. A smaller secondary variation has been observed in spring.

The same pattern has been observed in other mammals, which supports the idea that it is a genuine seasonal rhythm rather than a coincidence of behaviour or environment.

In the southern hemisphere this places the peak shed in the Australian autumn, roughly March through May, rather than the September to November period reported in northern hemisphere literature.

How long it lasts

Seasonal shedding is typically a matter of weeks rather than months. Follicles that released a hair during the shed re-enter the growth phase, and the density recovers as those new hairs grow through.

Because hair grows at roughly a centimetre a month, the recovery is not immediately visible. It takes some months for the replacement hairs to reach a length where they contribute to apparent density, which is part of why the shed feels more alarming than it is.

If you are still shedding heavily six or more weeks after it started, or if density has not recovered by the following summer, it is worth getting assessed rather than waiting another season.

Telling it apart from pattern hair loss

This is the distinction that matters, because the two require completely different responses.

Seasonal shedding is diffuse. Hair comes out from across the scalp fairly evenly, and the hairs that shed are full-length and normal in calibre. Your hairline does not move. Your part does not widen. Density returns.

Male or female pattern hair loss is progressive and patterned. In men it typically begins at the temples and the crown. In women it more often presents as widening of the part and diffuse thinning across the top. The hairs that replace those shed become progressively finer and shorter over years, a process called miniaturisation, until they no longer produce visible hair at all.

The clearest practical difference: seasonal shedding is a temporary increase in the rate of loss. Pattern hair loss is a permanent change in the quality of what regrows.

Both can happen at once, which is often why someone notices their pattern loss for the first time during an autumn shed. The shed is temporary. What it revealed is not.

See male pattern baldness and the Norwood Scale and how much hair loss is normal.

Other things that cause diffuse shedding

Seasonal variation is not the only reason for a sudden diffuse shed, and it is worth ruling out the alternatives, particularly if the timing does not fit.

Telogen effluvium is a shed triggered by a physiological stressor: significant illness, surgery, high fever, childbirth, rapid weight loss, or severe psychological stress. Characteristically it appears two to three months after the trigger, which is why the cause is often not obvious.

Thyroid dysfunction, both under and over-active, commonly affects hair.

Iron deficiency is a frequent contributor, particularly in women.

Certain medications can precipitate shedding, including some antidepressants, anticoagulants, retinoids and beta blockers.

If a diffuse shed does not resolve, these are worth investigating with your GP, ideally with bloods. See when hair loss isn't genetic.

What actually helps

Honestly, not a great deal, and that is the useful thing to know.

Seasonal shedding resolves because the follicles were never damaged. They released a hair and re-entered the growth phase. No product accelerates that, and anything marketed as reversing seasonal shedding is claiming credit for something that was going to happen anyway.

What is worth doing:

Leave it alone. Aggressive brushing, tight styling and frequent heat during a shed adds mechanical loss on top of the physiological loss. Being gentler reduces the amount you see.

Address any genuine deficiency. If your ferritin, iron or thyroid function is abnormal, correcting it matters. If they are normal, supplementing does not add benefit. This is a question for bloods, not guesswork. See diet and hair health.

Avoid tight styles. Sustained tension causes traction alopecia, which is a separate and potentially permanent problem. See traction alopecia.

Photograph it. Monthly photos of your hairline and part in consistent lighting will tell you more over six months than daily observation will.

What we would not recommend is starting a treatment regime in reaction to a seasonal shed. If the shed resolves, you will attribute the recovery to the treatment. If you have underlying pattern loss, you want that assessed properly rather than self-managed.

When to get it looked at

Reasonable triggers for seeking assessment:

• Heavy shedding continuing beyond about six weeks
• Density that has not recovered by the following season
• Visible scalp where it was not visible before
• A widening part or a receding hairline
• Shedding accompanied by fatigue, weight change or other symptoms
• Patchy loss rather than diffuse loss

The advantage of getting assessed early is that the options are broader when loss is caught early. Once follicles have miniaturised past a certain point, there is less to preserve.

The short version

Autumn shedding is real, common and usually temporary. It is a shift in the timing of the hair cycle, not damage to the follicles.

What is worth paying attention to is whether density recovers, and whether the hair growing back is the same as what was there before. If it is finer, shorter or not returning, that is a different problem and one worth having looked at.

A GP referral is required before a cosmetic surgery consultation. If you would like your hair loss assessed, get in touch.

Related reading: how much hair loss is normal, hair loss treatments compared, everyday habits that damage your hair.