Tag Archive: dandruff

How does shampoo work?

November 11, 2018

 

What constitutes a good shampoo?

Caring for one’s hair is just as important as caring for one’s face, but often gets less attention. Understanding what constitutes a good shampoo is an important part of making sure your hair stays healthy and voluminous.

To help you navigate the world of shampoo products, we introduce you to the basics you need to know.

How should a shampoo function? 

A shampoo is expected to cleanse the scalp and hair of dirt, sebum, sweat, dead skin cells and environmental pollutants. It also should remove greasy residues from hair care products such as oils, gels and sprays.

While most shampoos can accomplish a thorough cleanse, the real challenge lies in removing just enough sebum to allow the hair to be clean without drying it out.

This explains why most shampoo formulations have a secondary function of smoothing the hair’s surface and imparting lustre, smoothness, buoyancy and volume.

Ingredients

Typical shampoos contain 10 to 30 ingredients. These include: cleansing agents (surfactants), conditioning agents, special care ingredients, and additives. The surfactants are responsible for cleansing hair while the conditioners and other ingredients do the rest.

Types of surfactants

A surfactant is often amphiphilic, meaning its molecules contain both lipophilic (oil-attracting) and hydrophilic (water-attracting) parts. The oil-attracting parts bind to sebum while the water-loving sites parts to water. Such a mechanism allows sebum to be removed when in contact with water.

The type of surfactants used in shampoos is classified according to their hydrophilic polar group. The four common categories of shampoo surfactants are anionics, cationics, non-ionics and amphoterics. Most shampoo formulas rely on two types of surfactants.

The surfactant listed first in a shampoo’s ingredient list denotes the primary cleanser and also the ingredient in the highest concentration. The surfactant listed second is the secondary cleanser; this is often added to offset the weaknesses of the first surfactant.

Anionic surfactants

Anionic sufactants are named for their negatively charged hydrophilic (water-loving) parts. Derived from fatty alcohols, they are good at removing sebum from the scalp. However, excessive cleansing with anionic surfactants leaves the hair harsh, rough, dull, frizzy and prone to tangling.

Cationic surfactants

In contrast to anionic surfactants, cationic sufactants have a positively charged element. Cationic surfactants are poor cleansers and do not lather well. They are also not compatible with anionic surfactants. However, they are excellent at keeping chemically damaged hair soft and manageable. As a result, shampoos for damaged or coloured hair often include cationic surfactants. Examples include long-chain amino esters, ammonioesters, and cetyltrimethylammonium chloride.

Amphoteric surfactants

With both positively and negatively charged groups, amphoteric surfactants foam well and condition the hair. In addition, they do not cause stinging in the eyes and are gentle on the skin/scalp barrier, making them ideal for mild shampoos. Examples are betaine, sulfonate betaine, amphoteric acetate/diacetate.

Nonionic surfactants

Nonionic sufactants do not have a charged group and hence are compatible with any surfactant. Nonionic surfactants are the mildest type of surfactant but lather poorly. Such surfactants are often used in baby shampoos. Examples are fatty alcohol ethoxylates, sorbitan ether esters, and alkyl polyglucosides.

Conditioners (in shampoo formulations)

Shampoo formulations tend to add hair-conditioning ingredients to impart manageability, gloss and antistatic properties to the hair. Many are noted as ‘2 in 1’ to indicate the presence of both cleansing and conditioning benefits.

Examples of conditioning ingredients are fatty substances such as vegetable oils, wax, lecithin and lanolin derivatives, protein by-products (collagen, silk, animal proteins) and silicones.

Silicones add lubricity to the hair and reduce friction that arises from combing. They make it easier to comb through and detangle strands and prevent them from becoming frizzy.

Protein substances found in conditioners function by temporarily mending split ends and holding the hair fragments together until the next shampooing takes place.

Speciality additives

To stand out in the market, certain shampoos may offer other attractive ingredients such as panthenol, pro-vitamins or botanicals such as tea tree oil. However, given that the contact time of shampoo with the scalp and hair is brief, it is unlikely that these provide significant clinical benefits. Such additives function more as a marketing tools.

Shampoos for special conditions

For shampoos that target conditions such as dandruff or seborrhea (oily scalp), active ingredients are added.

Dandruff is often due to the overgrowth of a yeast called Malassezia spp. Anti-dandruff shampoos rely on ingredients that can inhibit the overproduction of yeast cells. Such ingredients include zinc pyrithione, ketoconazole and selenium disulphide.

For patients with oily scalps, coal tar can be an effective ingredient in reducing sebum production.

For deep cleansing of the scalp with pharmaceutical grade ingredients, consider Deep Cleanse Shampoo. It degreases oily scalps, calms irritated or sensitive scalp problems and improves hair loss control, This shampoo also contains zinc pyrithione to target dandruff, thus suitable for many hair types.

© 2018 TWL Specialist Skin and Laser Centre. All rights reserved.

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Meet with Dr. Teo Wan Lin, an accredited dermatologist at TWL Specialist Skin & Laser Centre, for a thorough consultation to determine the most suitable treatment for your skin.

To book an appointment with Dr. Teo, call us at +65 6355 0522, or email appt@twlskin.com. Alternatively, you may fill up our contact form here.

A Dermatologist’s Best Guide to Hair Loss Treatments for Your Sensitive Scalp

October 5, 2017

By Dr. Teo Wan Lin, Consultant Dermatologist at TWL Specialist Skin & Laser Centre

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In the third installment of my series on dealing with hair loss in Singapore as a dermatologist, I’m going to discuss dandruff and scalp sensitivity. This is one of the commonest scalp complaints that my patients have in conjunction with hair loss symptoms and leaves many of them wondering if it is the cause of their hair loss problem.

1. What is dandruff and what causes it?

Flaking on the scalp and white scales found on one’s clothes are one of the first symptoms of dandruff, which is lay speak for any form of scalp inflammation that causes the cell turnover rate on the scalp to increase abnormally. There are several medical conditions that can result in this, the commonest being the following: scalp psoriasis, seborrheic dermatitis and scalp eczema.

2. Do I have a sensitive scalp or is it a symptom of another condition?

Do you have itch, redness or pain on your scalp? You may have an undiagnosed inflammatory scalp disease. Scalp “sensitivity” without any underlying scalp condition is a very rare condition attributed to abnormal nerve sensations known as scalp dysaesthesia.

It is far more common to have an underlying cause such as seborrheic dermatitis, which is due to proliferation of a yeast known as malessezia furfur in an individual with excess production of oil. It is also commoner in tropical and humid climates such as Singapore, as it encourages this yeast to grow. Otherwise, malessezia is an inhabitant of one’s skin and scalp. Under normal conditions, it does not cause any issues, however under humid and sweaty environments, this yeast can proliferate to cause scalp inflammation and flaking. If you have scalp flaking which does not respond to over the counter anti-dandruff shampoos, which usually contain zinc pyrithone which is anti-fungal, promptly seek the care of an accredited dermatologist rather than self medicate or DIY.

Other causes of scalp inflammation would be scalp eczema, which is due to an excessively dry scalp/skin condition, scalp psoriasis, which may be the case especially if one has a family history of psoriasis or rashes on one’s body. If you have been in contact with a ringworm infected cat or dog, also do have your scalp and skin checked by a dermatologist as these infections are contagious and could also cause a form of scalp inflammation presenting as a red, scaly and itchy patch with hair loss.

3. Is my sensitive scalp causing hair loss?

Most cases of scalp inflammation due to eczema, seborrheic dermatitis, scalp folliculitis or psoriasis should not cause hair loss. However severe inflammation can push the hair growth cycle into a stage of telogen effluvium which is when hair reaches the end of its cycle and falls out, similar to hair loss that occurs after a major illness or post-pregnancy. In addition, if one picks and peels off crusted areas over the scalp this can also cause damage to the hair root and lead to hair loss. There are other causes of hair loss such as alopecia areata, which is an autoimmune disorder causing one’s immune system to attack hair follicles, leading to hair loss. This usually has no symptoms other than the appearance of round patches of hair loss over one’s scalp. Scarring causes of hair loss include folliculitis decalvans, which is the end-stage of a type of scalp folliculitis, whereby the hair follicles themselves are constantly inflammed and infected. Children may be more susceptible to tinea capitis, which is a fungal scalp infection that can lead to scarring hair loss if untreated.

© 2017 Dr. Teo Wan Lin. All rights reserved. 

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Meet with Dr. Teo Wan Lin, founder and Specialist Consultant Dermatologist of TWL Specialist Skin & Laser Centre, an accredited dermatologist specialising in medical and aesthetic dermatology. She integrates her artistic sensibility with her research background and specialist dermatologist training, by means of customised, evidence-based aesthetic treatments using state-of the-art machines, injectables (fillers and toxins) which work synergistically with her proprietary line of specialist dermatologist grade cosmeceuticals Dr.TWL Dermaceuticals.

To book an appointment with Dr. Teo, call us at +65 6355 0522, or email appt@twlskin.com. Alternatively, you may fill up our contact form here.