90 days to Beautiful Hair - Part 1: Finding products to grow healthy hair

As we are stuck at home due to lockdown, we have plenty of time to take care of ourselves from head to toes. We are not going to lie; we quite enjoy this peaceful time to reflect and finding new ways of reinventing ourselves. One of our goals for this New Year was to grow healthy hair by building a hair care routine and sticking to it. It’s not always easy to follow a routine especially when life gets in your way. But now it is the right time to do it.
There are so many videos from YouTubers on hair routine, but we want to give ourselves some time away from the screen. As we love to read books, we decided to find one written by a medical expert to get a different perspective.
While searching for a book we found this ‘90 Days to Beautiful hair' from Dr. Crystal Aguh. 


Book Front Cover

We already knew the work of Dr. Aguh as we had previously read her textbook ‘Fundamentals of Ethnic Hair - The Dermatologist’s Perspective’ that she co-wrote with Dr. Ginette Okoye.

This new book was the perfect match: tips from a dermatologist and beautiful for in 90 days. It felt like the recipe to challenge ourselves to a new routine for 90 days.


About the book

This book review will summarise the information and advice from Dr. Aguh to get beautiful hair whether you have straight, wavy, curly or coily hair.
We will split the reviews into two main parts. First, we will talk about the products you could include in your new routine to get beautiful hair. Then we will see how various practices, hair maintenance and nutrition play a role in a healthy growth.
But before getting into details with the book, let’s review some basics about hair.

Hair structure

The below image illustrates the hair structure


Hair Anatomy

Hair structure – Image from Design Essential NL

We will focus on two parts: the sebaceous gland and hair shafts.

Sebaceous glands are found in our skin and are attached to the hair follicle. They release natural oil called sebum that lubricates the hair shafts.

Hair shafts are made of three main parts:

  • The cuticle is the external layer made of flat overlapping cells to protect the cortex from chemicals and water.
  • The cortex is the middle layer made of keratin. It contains melanin which defines our hair colour.
  • The medulla is the innermost layer. Not all the hair types have medulla in their hair shafts. Generally, it is found in thick and coarse hair.

Hair Types

Hair types vary from one person to another. It is not uncommon that someone may have different hair types on their head.
The famous celebrities’ hairstylist Andrew Walker developed his Hair Typing System to classify hair based on their hair care needs.

 Andre Walker's Hair Typing System


Now that we have reviewed the basics let’s talk about products

Finding the right hair products for your routine



Washing your hair with shampoo should be the first step in your routine. Because sebum attracts dirt, washing your hair with a shampoo will remove all the dirt and buildup. Shampoo frequency varies from one person to another and depends on the hair type.
Dr. Aguh explains that sebum on straight hair (Type 1 on the classification) goes all the way down through the hair shaft. This explains why hair may feel oily within 24 hours after washing them. Whereas on curly and coil hair, sebum does not travel all the way down to the tips, making them feel dry and not requiring to be washed frequently.

 Dr. Crystal Aguh’s recommendations

Hair Type

Shampoo Frequency

Straight – Type 1

Every other day

Wavy – Type 2

2 to 3 times a week

Curly  and Coily Type 3 &4

Every 1 to 2 weeks



Shampoo should be made of at least have one basic ingredient called surfactant as it attracts simultaneously dirt and water so dirt can be washed away easily.

There are four types of surfactants:

  1. Anionic surfactant is generally referred as sulfate
  • Carries a negative charge and is great at removing dirt and sebum but can be drying.
  • Some of the anionic surfactants are used in shampoos labelled as “clarifying” shampoo.
  • Pair it with a positively charged conditioner right after.
  • Good for straight hair and to remove buildup after wearing protective styles for several weeks (braided styles or weaves)
  • Avoid for curly, heat-damaged, coloured and chemically processed hair
  • Anionic surfactants, from most harsh to least harsh:
Sodium Lauryl Sulfate (SLS)
Sodium Laureth Sulphate
Sodium Lauroyl Sarcosinate
Ammonium Lauryl Sulfate
 Sodium Myreth Sulfate
Sodium C14-16 Olefin Sulfonate
Disodium Laureth Sulfosuccinate
  1. Cationic surfactant
  • It has a positive charge and is safe to use on a regular basis
  • Cationic surfactants:
Behentrimonium methosulfate
Cenzalkonium chloride
Cetrimonium Chloride
Stearamidopropyl Dimethylamine
  1. Non-ionic surfactant
  • It has no charge and is gentle on all hair types, and is recommended for curly and coily hair. It works well with other shampoo ingredients
  • Non-ionic surfactants :
Decyl Glucoside
Lauryl Glucoside
Cocamide MEA
  1. Amphoteric surfactant
  • It has a negative and positive charge, which cancel each other out leaving a neutral charge on your hair
  • Some people may be sensitive to amphoteric surfactants. Avoid if you are aware of any sensitivity
  • Amphoteric surfactants:
    Cocamidopropyl Betaine
    Disodium Cocoamphodipropionate



    Conditioner plays an important role to restore the natural charge on your hair after shampooing, especially if you have applied a very harsh shampoo. A conditioner can be seen as a replacement to natural sebum for curly, coily and damaged hair. Because sebum does not go through the hair shaft, applying a conditioner will prevent hair to be dry.

    They also have mild cleansing abilities and may be used as an alternative to shampoo if your hair is not too dirty. When conditioners are used for that purpose, they are labelled as Co-wash.

    Dr. Aguh’s recommendations

    Do not overuse conditioner over time as it attracts dirt and may create buildup.

    Washing your hair with a conditioner only will be less effective if you want to follow with a deep conditioning or protein treatment.



    Now that we understand why a conditioner is essential in our routine, we want to know what kind of ingredients they should have.

    Here’s a list of some ingredients that you should look for in your conditioner:

    Stearyl alcohol or cetyl alcohol:  These ingredients will help to soften your hair but also to minimise friction for less tangle and split

    Dimethicone: This is a type of silicone that will make you hair feel smooth and shiny.
    It is usually found in hair serum leave-in and rinse-out conditioners.

    Hydrolysed keratin / Collagen / Elastin: They contain protein that add strength to your hair. Avoid using it if you do a protein treatment as it will contain some of these ingredients already.

    Citric acid /Benzoid acid /Glutamic acid: They leave a positive charge on your hair to reduce frizz. They are definitely the ingredients to look for if you want manageable and shiny hair.



    Deep conditioning is strongly recommended for damaged hair, or if you experiencing breakage. Their action is more intense that regular conditioners. For a deeper action, you should ideally use heat the it will lift the hair cuticles so the conditioner will penetrate more deeply.

    Dr. Aguh’s recommendations on deep conditioning frequency

    Healthy naturally curly/kinky: Once a week

    Damaged naturally curly/kinky: Twice a week with protein treatment once a week

    Healthy straight/wavy : Once a month

    Damaged straight/wavy: Alternate deep conditioning and protein treatments every other week during 3 months



    Leave-in conditioners have the same action as regular conditioners but they are not washed out but rather left on hair to keep it moisturised, especially for dry hair.

    Leave-in conditioners can either be water-based on cream-based.

    Dr. Aguh’s recommendations

    Straight/wavy/colored/heat damaged : Use water based leave-in on wet hair after shampoo and conditioner

    Curly/kinky/natural hair: se either water or cream based leave-in after shampoo and conditioner

    5 to 7 during the week

    Apply oil to trap moisturize afterwards


    Damaged hair

    If you have damaged hair, protein treatment in your regimen is a must. Protein treatment products are made of small or hydrolysed proteins that would enter the hair shaft leading to stronger hair. Similarly to deep conditioning, using heat will provide a deeper action.

    Dr. Aguh recommendations

    For severely damaged hair, protein treatment should be done once a week for at least 1 to 3 months.

    Now that you know what kind of products and ingredients are best for your hair, you can navigate the hair care aisle with confidence.

    About the author

    Crystal Aguh, M.D FAA,is  a board-certified dermatologist  as well as director of the Hair Loss and Scalp Disease  clinic and Ethnic Skin Centre  at Johns Hopkins School of Medicine in Baltimore (USA).

    She wrote various articles on ethnic skin and is the co-author of the textbook "Fundamentals of Ethnic Hair-The Dermatologist's Perspective”.  

    Dr. Crystal Aguh
    Crystal Aguh M.D
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