What Causes Sudden Hair Shedding? Common Triggers and When to Seek Help
Experiencing sudden hair shedding? Learn about the most common causes, including stress, hormonal changes, illness, nutritional deficiencies, and telogen effluvium, plus when to seek medical advice.
What causes sudden hair shedding?
If you have noticed more hair than usual coming out when you brush,
wash or style it, it can feel unsettling, particularly if it seems to happen
quite suddenly. Sudden hair shedding is often linked to a condition
called telogen effluvium, which occurs when a larger than usual
proportion of your hair shifts into the shedding phase of the hair growth
cycle at the same time. While this can feel alarming, it is usually a
response to a trigger rather than permanent hair loss.
Hair growth cycle and shedding explained
Your hair naturally grows in cycles, with each strand moving through a
growth phase, a transitional phase and a resting phase before it sheds.
At any given time, a small percentage of your hair is in the shedding
phase, which is why daily hair loss is normal. With sudden shedding,
more hairs than usual enter this resting phase together, leading to
noticeable thinning or increased hair fall.
Common triggers of sudden hair loss
There are several factors that can disrupt your hair cycle. Physical or
emotional stress is one of the most common, including illness, surgery or
significant life events. Hormonal changes can also play a role,
particularly after pregnancy or when stopping or starting hormonal
contraception. Nutritional factors are another consideration, especially if
you have experienced rapid weight loss or have low levels of iron,
vitamin D or other key nutrients. Even changes in medication can
contribute to increased shedding.
Hormonal changes and hair thinning
Hormones have a direct influence on hair growth, and fluctuations can
affect how long your hair remains in the growth phase. In your thirties
and beyond, subtle hormonal shifts can begin to influence hair density
and texture. You may also notice changes after pregnancy or during
periods of hormonal imbalance, where shedding becomes more
noticeable for a period of time before stabilising.
When to seek advice for hair shedding
While sudden hair shedding is often temporary, it is important for you to
seek advice if it persists beyond a few months, becomes more severe or
is accompanied by other symptoms such as fatigue, irregular periods or
changes in your skin. A medical assessment can help identify any
underlying causes and ensure that appropriate investigations, such as
blood tests, are carried out if needed.
Final thoughts
If you are experiencing sudden hair shedding, it is usually a sign that
your body has responded to a recent stress or change rather than an
indication of permanent hair loss. The hair growth cycle often resets
itself over time once the underlying trigger has resolved. Taking a
balanced approach that supports your overall health, including nutrition,
stress management and gentle hair care, is often the most effective way
to allow your hair to recover naturally.
Dr Sreedhar Krishna is a UK-based Consultant Dermatologist with a specialist clinical focus on acne, including the safe prescribing and monitoring of isotretinoin and other systemic acne treatments. He is the Chief Medical Officer and co-founder of skindoc, a consultant-led dermatology service providing both in-person and online care. His work centres on evidence-based acne management, patient safety, and maintaining high clinical standards in UK digital dermatology.
