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Why Is My Hair Thinning

A very common question professional haircare experts are asked is "Why is my hair thinning?" There are several possible answers, which we're about to explain in uncomplicated terms so that you can find the best solution for thicker and healthier-looking hair.


Hair thinning is not necessarily due to aging, although it is common to see a gradual thinning of hair as we grow older due to our scalp stem cells weakening and slowly ceasing hair production as we age. But hold on, before you give up on hopes of thicker-looking hair, age might not be all there is to it...


Before you can understand why your hair is thinning, there are some important distinctions to make. There is a difference between a) a change in the texture of your hair, b) a reduction in hair growth, and c) hair loss/hair dropping out.


The texture of the hair can evolve throughout our lives due to changes in the hair follicle (where the hair fibre is produced). This can be caused by damage over time, perhaps due to repeated pulling or medication. The structure of already-existing hair fibres can also be permanently changed as a result of over-processing, where the fibre loses its natural form (such as curls), becoming weaker and thinner. Hormonal changes, such as pregnancy or the menopause, can also affect the natural texture of the hair, resulting in thin hair.


A reduction in hair growth could also be the reason behind your thinning hair. On average, we shed about 100 hairs 1 per day, which might sound a lot, but the human head is estimated to have around 100,000 hairs at any one time, although this varies considerably depending on factors such as age and genetics. A recent study published in Science magazine2 has suggested that the stem cells responsible for stimulating the production of new hair may, over time, be altered and turn into skin cells (called epidermal keratocytes), which are then shed with the rest of the skin. Scarring can also prevent new hair growth, as well as scalp conditions. 


Is your hair really thinning or is it actually falling out? Literal hair loss, where pre-existing hairs fall out before they should naturally, can be due to several reasons. Medical treatments (chemotherapy) and conditions such as alopecia can be behind the phenomenon, and research also suggests that nutritional deficiencies3 could be the cause of hair falling out. The pulling out of hair, or consistent tension on the hair itself has also been connected4 with losing hair as a result of weakened follicles that hold the hair in place.



If your hair's thinner appearance is due to a change in texture (weaker, finer-feeling hair), hair falling out or a reduction in new hair growth, here's what you should try! The first step is to reduce, if not stop entirely, harsh styling that pulls at the head. Aggressive brushing and hairstyles that create tension on the scalp may be causing excess hair loss and damaging your hair-producing follicles. A way of supporting the growth of new hair could be a great excuse for some pamper time... Research5 suggests that regular scalp massages stimulate blood circulation and in turn promote the development of healthy new hair fibres. A head massage will also help the production of natural oils, which moisturise the hair shaft, keeping hair smooth, supple and shiny and reducing dryness, split ends and breakages.
Tailored haircare could leave "why is my hair thinning?" a question of the past. The Serioxyl haircare collection by L'Oréal Professionnel has been formulated to help thicken and lift thinning hair. Try the Serioxyl Denser leave-in hair spray on a daily basis for three months, and see your hair thicken and regain its healthy volume. 

If you've noticed your hair thinning, make an appointment with your local L'Oréal Professionnel hair stylist, who will help determine the clause and choose the best course of treatment. Trust the experts!



1Carina A. Wasko, MD; Christine L. Mackley, MD; Leonard C. Sperling, MD; Dave Mauger, PhD; Jeffrey J. Miller, MD, "Standardizing the 60-Second Hair Count" Arch Dermatol. (2008), 144 (6), pp.759-762.

2Hiroyuki Matsumara et al. "Hair follicle aging is driven by transepidermal elimination of stem cells via COL17A1 proteolysis" Science Vol 351, Issue 6273 (2016), (published here:

3.Guo EL, Katta R. "Diet and hair loss: effects of nutrient deficiency and supplement use." Dermatology Practical & Conceptual. 2017;7(1):1-10. doi:10.5826/dpc.0701a01.

4.Haskin, Alessandra et al. "All hairstyles are not created equal: What the dermatologist needs to know about black hairstyling practices and the risk of traction alopecia (TA)" Journal of the American Academy of Dermatology , Volume 75 , Issue 3 , 606 – 611 (accessed here:

5.Koyama, Taro et al. “Standardized Scalp Massage Results in Increased Hair Thickness by Inducing Stretching Forces to Dermal Papilla Cells in the Subcutaneous Tissue.” Eplasty 16 (2016): e8. (accessed here: