A greasy scalp results from hyperactivity of the sebaceous glands, often influenced by hormonal factors. This seborrhoeic overactivity may sometimes be accompanied by more or less pronounced hair loss. Mere coincidence or a genuine biological link? Find the answer to this question below.
Keywords: itchy oily scalp and hair loss, hair that becomes oily quickly and falls out, oily hair causing itching followed by hair shedding, oily hair that falls out
Oily hair results from hyperseborrhoea linked primarily to androgen activity and the enzyme 5α-reductase.
Hair loss depends on the hair growth cycle and can be influenced by hormonal, inflammatory, genetic or environmental factors.
Sebum itself does not directly cause hair loss, but an excess can alter the scalp environment.
Studies have shown differences in lipid composition and microbiota in individuals with an oily scalp associated with hair loss.
Low-grade chronic inflammation, driven by an imbalance of sebum and the microbiota, can disrupt the hair growth cycle.
Oily hair results from hyperseborrhoea, that is, an excessive sebum production by the sebaceous glands of the scalp. This hyperactivity is primarily influenced by androgenic hormones. Testosterone is locally converted into dihydrotestosterone (DHT) by the enzyme 5α-reductase within sebaceous cells, which stimulates lipid synthesis and increases sebum secretion. High activity of this enzyme therefore predisposes to a greasier scalp. In addition to these hormonal factors, environmental elements such as stress, pollution, unsuitable hair care products, or a diet with a high glycaemic index can indirectly exacerbate androgen production and seborrhoea.
of sebaceous glands on the body.
The hair shedding, for its part, is based on distinct mechanisms related to the hair cycle. Each follicle alternates between a growth phase (anagen), a transition phase (catagen) and a resting phase (telogen), at the end of which the hair falls out. An increased hair loss may result from a shortening of the anagen phase, a premature entry into telogen, a phenomenon known as "telogen effluvium", a progressive miniaturisation of the follicle as seen in androgenetic alopecia, or from scalp inflammation.
hair naturally falls out every day, and this does not constitute abnormal hair loss.
Thus, when individuals report hair that becomes oily rapidly and undergoes shedding, it is important to remember that sebum production and follicular dynamics involve distinct biological processes, even though they may influence each other.
In theory, sebum is not an enemy of hair. It contributes to the lubrication of the fibre and to the protection of the scalp. However, an excess can alter the follicular environment by influencing the local lipid composition and the balance of the microbiota. It is in this context that some people describe an oily, itchy scalp leading to hair loss. The question is therefore not so much the presence of sebum as its excess combined with possible inflammatory or microbial alterations.
A recent study conducted in young women aged 18 to 35 years with oily scalps and hair loss highlighted significant differences compared with a control group, both in terms of scalp physiological parameters and in lipid composition and microbiota. Eight differential lipids were identified, mainly ceramides, triglycerides and diglycerides. Ceramides, essential components of the skin barrier, are also involved in cellular signalling and apoptosis. Abnormal accumulation could thus disrupt the follicular environment. Moreover, two lipid metabolic pathways, including the sphingolipid pathway, were associated with the observed profiles. This pathway is involved in the production of bioactive molecules, such as sphingosine-1-phosphate, which play a part in regulating cell growth and inflammatory responses. Dysregulation could therefore influence both sebum production and the hair cycle.
The study also highlighted differences in the composition of the scalp microbiota. Variations in the abundance of bacteria, such as Cutibacterium or Pseudomonas, as well as yeasts like Malassezia, were observed. These micro-organisms closely interact with sebum lipids: certain yeasts hydrolyse triglycerides and release fatty acids capable of irritating the scalp, promoting itchiness and local inflammation. Chronic inflammation, even at a moderate level, can impair the quality of the follicular environment and disrupt the hair growth cycle.
Differences in the scalp microbiome of young women presenting with oily scalps and hair loss compared with a control group.
Source: ZHAO F. & al. Multidimensional research on hair loss in young Chinese females with oily scalps. Journal of Cosmetic Dermatology (2025).
Nevertheless, the authors emphasise that this is an observational study: the associations identified do not allow one to assert that a greasy scalp directly causes hair loss.
In conclusion, an oily scalp does not mechanically cause hair loss, because sebum production and the hair growth cycle are governed by distinct biological mechanisms. However, excess sebum can alter the scalp’s ecosystem, promote microbial imbalances and sustain low-grade chronic inflammation. Moreover, an inflammatory follicular environment is likely to disrupt the hair growth cycle and exacerbate certain forms of hair shedding, particularly in individuals who are already predisposed. Thus, while hair that becomes oily quickly does not necessarily shed more rapidly than other hair, an imbalanced scalp can constitute an aggravating factor in hair loss.
SHUSTER S. & al. Control and function of sebaceous glands. Physiological Reviews (1989).
HU Z. & al. Effect of behavioral factors on severity of female pattern hair loss: An ordinal logistic regression analysis. International Journal of Medical Sciences (2020).
SIVAMANI R. K. & al. Integrative and mechanistic approach to the hair growth cycle and hair loss. Journal of Clinical Medicine (2023).
ZHAO F. & al. Multidimensional research on hair loss in young Chinese females with oily scalps. Journal of Cosmetic Dermatology (2025).
ZHENG Y. & al. Potential causal relationship between extensive lipid profiles and various hair loss diseases: Evidence from univariable and multivariable Mendelian randomization analyses. rnal of Cosmetic Dermatology (2025).
