Late-summer hair shedding: what is normal and what is not

Each follicle works independently through three phases: a long active growing phase, a short transitional phase, and a resting phase at the end of which the hair is released and a new one begins underneath. A steady amount of daily shedding is the normal output of that system.

Because follicles are not synchronised, this normally happens quietly in the background. What people notice is a change in proportion: a larger share of follicles entering the resting phase together, so a larger share release their hairs together some weeks later.

Seasonal variation in hair shedding is a documented pattern rather than folklore. A larger proportion of follicles tends to enter the resting phase during the summer months, and since the hair is released at the end of that phase rather than at its start, the visible shedding arrives afterwards, in late summer and autumn.

That lag is the single most useful thing to understand about shedding in general. What you see today reflects what your follicles did some time ago, not what is happening to you this week.

Telogen effluvium is the name for diffuse shedding that follows a systemic event. A high fever or significant illness, surgery under general anaesthetic, childbirth, rapid or substantial weight loss, a severe emotional period, a new medication or a nutritional deficiency can all push an unusually large share of follicles into the resting phase at the same time.

The shedding then appears two to three months later, which is long enough that the connection is rarely made. It is diffuse, affecting the whole scalp rather than patches, and it is self-limiting in most cases: the follicles are alive and resting, not lost.

Recovery generally follows over the following months once the trigger has passed, though regrowth is slow because hair grows slowly. Patience is genuinely part of the treatment here, uncomfortable as that is to hear.

In shedding, whole hairs are released across the scalp and the density of what remains is broadly even. In pattern hair loss the process is different: follicles gradually produce finer, shorter, less pigmented hairs over years, and the change is concentrated in particular regions, the crown and temples in men, a widening central part in women.

The two can coexist, and a period of shedding often makes an underlying pattern visible for the first time, which is why some people date their hair loss to an illness that in fact only revealed it.

Diffuse shedding after a recognisable trigger, with a normal-looking scalp, usually warrants patience and a review if it has not settled. The following do not.

The first step is a history rather than a product: when it started, what happened three months before that, what medications and supplements you take, whether anything else has changed. Blood tests are often useful, commonly to look at iron stores, thyroid function and vitamin D, since deficiency-related shedding responds to correcting the deficiency rather than to anything applied to the scalp.

Separately, some hair is not being lost but broken. Tight styles that pull on the roots cause a genuine and preventable form of loss over time, and heat and chemical processing cause breakage that looks like thinning. These are worth addressing regardless of what else is going on.

In-clinic options exist, and their evidence varies by condition and by individual. They are worth discussing after the cause has been identified, not instead of identifying it. Any timeline for visible change is measured in months, because that is the speed at which hair grows.