Telogen Effluvium in Women: What This 2026 Study Found About Stress, Illness, Ferritin and Vitamin D
- Gwen Adey
- May 9
- 5 min read
Why do some women suddenly start losing handfuls of hair a few months after stress, illness or dieting?
A new 2026 study from researchers at Sechenov University in Moscow adds more evidence to something many hair specialists already suspect:
Acute telogen effluvium (TE) is often not caused by one single thing.
Instead, it is frequently the result of multiple stresses hitting the hair follicle at the same time.
The researchers looked at 60 women aged 18–45 with sudden diffuse hair shedding lasting between 2 and 6 months. They investigated possible trigger factors, blood tests, hormones and phototrichogram findings (a detailed computerised analysis of hair growth cycles).
What they found will sound very familiar to many women reading this.
What Is Telogen Effluvium?
Telogen effluvium is a form of diffuse hair shedding where more hairs than normal shift into the resting (“telogen”) phase of the hair cycle.
Normally, around 85–90% of scalp hairs are actively growing at any one time.
In telogen effluvium, a larger proportion prematurely switches into the resting phase. Around 2–4 months later, those hairs begin shedding.
This is why many people only connect the dots retrospectively:
“I had COVID three months ago.”
“I went through a bereavement.”
“I lost weight rapidly.”
“I had surgery.”
“I stopped eating properly.”
“I’ve been under enormous stress.”
The hair shedding is often delayed.
The Most Common Trigger Factors
The most common trigger factors identified in the study were:
Previous infections — 63.3%
Psychological stress — 56.7%
Weight change — 28.3%
COVID-19 was particularly common in the infection group.
This fits with what many dermatologists and hair clinics saw globally after the pandemic: people developing dramatic shedding several months after infection.
The researchers discuss how systemic illness, fever, inflammation and physiological stress may “shock” follicles into prematurely leaving the growth phase.
But perhaps the most important point in this paper is that many women did not just have one trigger.
They had several.
Stress plus low ferritin.
Illness plus crash dieting.
COVID plus vitamin D deficiency.
This is probably closer to real life than simplistic “single cause” explanations.
Ferritin Was Low in More Than Half the Women
One of the strongest findings in the paper was the prevalence of low ferritin.
56.7% of the women had ferritin levels below 30 ng/ml.
Ferritin is a marker of stored iron.
Importantly, many of these women were not anaemic.
That matters.
Because hair follicles appear to be extremely metabolically demanding structures. The researchers point out that follicles may require iron stores to be substantially higher than the minimum needed simply to avoid anaemia.
This is something many hair specialists see clinically all the time:
A woman may be told her blood count is “normal”, yet still have depleted iron stores.
The study also found a statistical correlation between ferritin levels and the proportion of hairs in the telogen phase.
That does not prove low ferritin caused the shedding.
But it strengthens the argument that iron status deserves proper attention in diffuse hair loss assessments.
Vitamin D Deficiency Was Even More Common
68.3% of the women had vitamin D levels below 30 ng/ml.
That sounds dramatic at first glance.
However, we need to interpret this carefully.
Vitamin D deficiency is already extremely common in many populations, especially in northern climates. The authors themselves acknowledge this.
So this study does not prove vitamin D deficiency causes telogen effluvium.
But it does suggest vitamin D deficiency frequently coexists alongside it.
Biologically, the theory is plausible. Vitamin D receptors are involved in hair follicle cycling and signalling.
The unanswered question is whether correcting deficiency meaningfully improves shedding outcomes.
That still needs better long-term trials.
What About Hormones?
Interestingly, most women in the study did not have major hormonal abnormalities.
That is important because many patients worry they must have “hormone problems” when they suddenly lose hair.
A small minority had:
mild thyroid abnormalities
thyroid antibodies
mildly raised testosterone markers
But overall, the findings support the idea that acute telogen effluvium is usually a reactive process rather than primarily a hormonal disease.
That helps distinguish it from androgenetic alopecia (female pattern hair loss), where follicle miniaturisation plays a central role.
One of the Most Interesting Parts of the Study
The phototrichogram findings were actually some of the most clinically useful parts of the paper.
The women had:
increased telogen hairs
but preserved terminal hair density
minimal miniaturisation
very few vellus hairs
That pattern matters.
Because it supports a diagnosis of acute shedding rather than progressive follicle shrinkage.
In simple terms:
The follicles are still largely intact.
They have just been pushed into a resting state.
That is often a more reassuring situation than true follicle miniaturisation disorders.
The Emotional Impact Was Significant
This was not “just cosmetic.”
The quality-of-life scores showed moderate psychological impact overall, with emotional distress being particularly prominent.
Women reported:
anxiety
reduced confidence
distress about appearance
social avoidance
This is something still underestimated by parts of medicine.
Hair loss can profoundly affect identity, femininity, confidence and social functioning.
Especially when it happens suddenly.
My Interpretation as a Hair Loss Clinician
This study does not “prove” that low ferritin or low vitamin D causes telogen effluvium.
But it does reinforce something important:
When someone develops sudden diffuse shedding, it is usually worth stepping back and looking at the whole picture.
Not just the scalp.
That means considering:
recent illness
major stress
weight loss
nutritional status
iron stores
thyroid function
vitamin deficiencies
medications
systemic health
In many cases, the shedding is the body’s way of signalling that something significant happened physiologically several months earlier.
And importantly, acute telogen effluvium is often reversible once the trigger settles and the hair cycle gradually normalises.
The Limitations of the Study
The researchers are appropriately cautious about the conclusions.
This was:
a relatively small study
with only 60 patients
no healthy control group
observational rather than interventional
unable to prove causation
So this should not be interpreted as proof that every woman with shedding needs supplements.
Nor does it prove that correcting ferritin or vitamin D alone will stop hair loss.
But it does support comprehensive assessment rather than dismissing diffuse shedding as “just stress.”
The Bigger Message
Perhaps the most useful takeaway from this paper is this:
Hair follicles are remarkably sensitive biological structures.
They respond not only to genetics, but also to illness, inflammation, stress, nutrition and systemic health.
And often, hair shedding is delayed.
By the time the hair falls out, the trigger may already be months in the past.
That delay is one reason telogen effluvium can feel so confusing and frightening for patients.
Written by Dr Gwen Adey BDS MFDS RCS
First published: 09/05/2026
If you’d like more evidence-based hair loss research explained in plain English, you can subscribe for updates here 👉
Comments