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Shaving hair is very important, don’t dare to wash it!
Dermatologists should often encounter patients with "greasy hair but dare not wash". They worry that their hair will get worse and worse as they wash, and that their hair will get less and less.
shampooing a long hair is a difficult task. You know what you understand, and the longer you get, the more you have the right to speak. Therefore, in the face of all kinds of distress, endure the growing greasy hair. It feels uncomfortable if you don’t wash it, and you’re afraid it’s bad for your hair after washing it.
But is this really the case? Can hair be washed frequently, or even every day? Let’s take a look at the things about washing your hair with this big question mark.
01 Why do we need to wash our hair?
First of all, we need to understand, what exactly do we wash our hair? There are many sources of “dirt” on our hair and scalp. Endogenous such as sebaceous gland secretion and metabolic shedding of epidermal cells; exogenous such as certain hair care products, air pollution, pollen, volatile substances (such as caused by tobacco smoke), etc.
hair covering the scalp forms a special epidermal microenvironment and corresponding unique microorganism population. The more wet and rich sebum, the more conducive it is to their growth. In our eyes, "dirt" is their food source. Reducing the frequency of shampooing can cause secreted sebum to accumulate on the scalp for longer.
Once sebum is secreted to the surface of the scalp, it will undergo chemical changes, and the longer it stays, the greater the changes. At the same time, "overnutrition" will make the bacteria extremely active. Then a chain reaction occurs, such as:
(1) Scalp sensitivity
Changes in sebum contains free fatty acids and oxidized lipids, as well as metabolite , the metabolite of Malassezia, which will stimulate the scalp. Higher scalp sebum levels have been widely accepted to be associated with scalp sensitivity, which can aggravate hair loss.
(2) Head itch
The metabolites of Malassezia such as oxidized free fatty acids continue to accumulate will produce stimulating reactions such as itching. Studies have observed that the itching level will rise significantly within 72 hours after washing your hair, which is consistent with the accumulation curve of sebum.
(3) Hair greasy
Scalp sebum accumulation, which is subsequently transferred to the hair, resulting in a greasy appearance of the hair, characterized by an oily shine and hair fiber adhesion.
(4) The accumulation of sebum can lead to an increase in the incidence of dandruff and even seborrheic dermatitis .
02 The impact of washing frequency on scalp and hair
Since the interval is not good, how long does it take to wash it? This article "The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions" provides us with more objective data for reference.
This study was divided into two parts: one was epidemiological study (no therapeutic intervention), and the other was therapeutic study .
Epidemiological study:
2 weeks of continuous observation time, 1,500 Chinese were included, aged 18-75 years old. There was no therapeutic intervention, and the frequency of hair washing was divided into: ≤1 time/week, 2 time/week, 3-4 time/week, 5-6 time/week and 7 time/week respectively. The main subject is conducted in the form of a questionnaire.
treatment type study:
5 weeks of continuous observation time, 60 Chinese were included, 18-50 years old. The research process consists of two consecutive stages. After the first stage of shampoo (specific shampoo and standard shampoo process), you will continue to wash your hair for 7 days. The second phase shampoo is used daily for the next 4 weeks.
(1) Effect of washing frequency on the scalp
The results of the questionnaire: As the frequency of shampoo increases, the degree of self-feeling "dandruff", "itting" and "drying" is significantly reduced. Reduction of sensory dandruff was consistent with the evaluation of the Adherent Scalp Flaking Score (ASFS). Satisfaction with hair condition increases with the increase in shampoo frequency (Figure 1).
Figure 1. The relationship between self-conscious "time of good hair condition every week" and washing frequency (references from the picture source)
Technical measurement: Indicators about scalp: total sebum content, oxidized lipids, ASFS, and odor data of scalp daily shampoo group is lower than that of the group without shampoo for 7 days. The lower the value indicates that the scalp is healthier (Figure 2).
Figure 2. The relationship between total sebum content, oxidized lipids, ASFS, odor and washing frequency;
yellow is the 7-day shampoo group, and blue is the daily shampoo group (Photo source reference)
(2) Effect of washing frequency on hair
(2) The results of the questionnaire: the feeling of "smooth" in did not significantly improve statistically, but the feeling of "hair loss" and "hair brittleness" were significantly improved.
technical measurements: data on total sebum content, oxidized lipids, greasy gloss and water absorption rate of hair (Figure 3). The daily shampoo group is lower than the group without shampoo for 7 days. The lower the value indicates that the healthier the hair. Image collection is more intuitive to see that the daily shampoo group has significantly improved the amount of fat in the scalp and hair compared to the 7-day shampoo group (Figure 4 and Figure 5).
Figure 3. The relationship between total sebum content, oxidized lipids, greasy gloss and water absorption rate and washing frequency;
Yellow is the 7-day shampoo group, blue is the daily shampoo group
Figure 4. Scalp collection image (the 7-day shampoo is not shampoo, the 7-day shampoo is not shampoo, the 7-day shampoo is not shampooed, the 7-day shampoo is not shampooed, the 7-day shampoo is not shampooed, the 7-day shampoo is not shampooed, the 7-day shampoo is not shampooed, the 7-day shampoo is not shampooed)
(3) Effect of washing frequency on hair quality
In addition, an important indicator to measure the impact of treatment on hair condition is the effect of shampoo on the internal lipids that construct the stratum corneum structure .
Excessive "torture" of hair such as repeated rinsing will lead to a reduction in beneficial lipids, which will reduce the penetration and structural integrity of the hair and become rougher in the hair. One of the claims against frequent hair washing is that the surfactant of shampoo will induce the extraction of beneficial lipids and stimulate the decompensated and excessive secretion of sebum in the sebaceous glands. Is this really the case?
This study used gas chromatography method to determine beneficial internal hair lipids, and the results showed that there was no significant difference in data between daily shampoo and 7-day no shampoo. In other words, frequent washing of hair will not affect the lipids inside the hair.
Summary
This study evaluates the impact of shampoo washing frequency on scalp and hair condition from both subjective and objective aspects, and provides detailed data.
Increase the frequency of hair washing is beneficial to normal scalp and seborrheic dermatitis scalp and has no negative impact on hair condition.
In general, increasing shampoo frequency is developing towards a trend of reducing scalp and hair problems. Specifically, how should individuals grasp the frequency of shampooing? It should be based on the time when dandruff, itchy hair and greasy hair in your hair. You can wash your hair in time if necessary. There is no need to worry that washing your hair frequently will affect hair quality, hair volume, and the more you wash it, the more itch itchy itchy itchy it becomes.
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References:
[1]Punyani S, Tosti A, Hordinsky M, Yeomans D, Schwartz J. The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions. Skin Appendage Disord. 2021 Apr;7(3):183-193.
[2]Kato K. Studies on sebum on scalp and shampoo: time-lapse changes in the amounts of severeceride and free fatty acid on the scalp and subjective symptoms for one week. Sanarwa ta Kwalejin Fasaha ta Jami’a ta Hokkaido. 1997;10:47–58.
[3]Misery L, Rahhali N, Ambonati M, Black D, Saint-Martory C, Schmitt AM, et al. Evaluation of sensitive scalp severity and symptomatology by using a new score. J Eur Acad Der- matol Venereol. 2011;25(11):1295–8.
[4]Masukawa Y, Tsujimura H, Tanamachi H, Narita H, Imokawa G. Damage to human hair caused by repeated bleaching combined with daily weathering during daily life activities. Exog Dermatol. 2004;3(6):273–81.
This article is first published: Medical Skin Channel
Author: Pei Sa
Address of this article: Tang Jiaoqing
Editor: Cilantro
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