The hair cycle
Each follicle alternates between three phases: anagen (growth, 2 to 7 years), catagen (transition, a few weeks) and telogen (rest and shedding, around 3 months). At any given time, 85% to 90% of hairs are in the growth phase.
Shedding becomes a problem when the proportion of follicles in telogen increases, or when the hairs that grow back are progressively finer.
Warning signs
These signs indicate that shedding has gone beyond normal and warrant a consultation:
- Visibly increased loss for more than three consecutive months
- Scalp more visible in light, or a progressively wider parting
- Thinner, more brittle hair, or hair that doesn't reach its usual length
- Bald patches, redness, flaking, pain or itching
- Shedding accompanied by fatigue, weight changes or menstrual changes
What tests to run
Assessment begins with clinical history and trichoscopy. Depending on the picture, blood tests are requested, including full blood count, ferritin, thyroid function, vitamin D, zinc and, in women, hormone profile.
Identifying a deficiency or thyroid dysfunction completely changes the treatment plan — which is why treating without diagnosing rarely works.
Available treatments
Once systemic causes have been corrected, targeted hair treatment includes hair mesotherapy, PRP, topical or oral therapy and photobiomodulation. In cases where no viable follicle remains, FUE hair transplantation restores density permanently.
In every case, progress is assessed with standardised photography at 3, 6 and 12 months — not by how many hairs seem to end up on the hairbrush.
Hair loss in women
In women, hair loss rarely creates bald patches: it's noticed mainly through a widening parting, a thinner ponytail and diffuse thinning at the top of the head. The most frequent causes are telogen effluvium (post-partum, restrictive diets, surgery, stress), iron deficiency, thyroid dysfunction and female pattern hair loss, which worsens during perimenopause.
Since two causes often coexist, effective treatment first corrects the systemic factor and only then — or in parallel — addresses the scalp itself.
Seasonal shedding and stress-related shedding
There's a physiological increase in shedding in autumn and, to a lesser extent, in spring: more follicles enter their resting phase at the same time. It lasts a few weeks and doesn't reduce overall density.
Stress-related shedding has a characteristic delay of two to three months between the triggering event and when the hair actually falls out — which is why many people don't connect the two. It's reversible once the trigger resolves.
What to do at home (and what's not worth it)
Some habits help, but none replace a diagnosis when shedding is persistent.
- Maintain a diet with enough protein and correct deficiencies confirmed by blood tests
- Wash your hair as often as needed — washing less doesn't reduce shedding, it just builds it up
- Avoid tight hairstyles, excessive heat and repeated harsh chemical treatments
- Be wary of shampoos, ampoules and supplements that promise to stop shedding without a diagnosis
- Photograph the scalp under the same light and angle month to month to assess it objectively