Introduction
Itchy scalp and face are a common and annoying problem. Often this strikes in more humid climates or for those who swim or play sports often. Sometimes, it can happen to anybody for no reason and just won’t seem to go away.
What causes itching of the skin?
There are many causes of itchy skin generally speaking. Sometimes it is cause by a non specific allergy such as a food or chemical in the environment. These allergic reactions tend to go away after the exposure has stopped and are altogether short lived.
If somebody has repeated itching of the skin across the whole body, they might have too much ‘histamine’, an itchiness chemical made in the gut. This may be due to a gut dysbiosis (imbalance of bacteria in the gut) or from a parasite. This is called hives or general urticaria.
An itchy scalp and face with flaking are special kinds of rash involving yeast or fungus. The oil in the skin that lubricates hair is excellent food for yeasts that naturally live in the environment. They can combine to form a chronic, annoying, dandruff like rash of the scalp and sometimes face. This is caused seborrheic dermatitis or dandruff.
What are yeasts?
Fungi are small organisms, abundant in nature and the open world, which are usually harmless but can inhabit our skin surface and take advantage of surface oils to make themselves at home. Thrush, athletes foot, seborrheic dermatitis (a red rash of the scalp, eyebrows or facial area) are a few examples. Fungi naturally live on plants and trees and float around the air.
There are broadly speaking two types of fungal infestation of the scalp.
One is superficial and is mostly flaking and is called dandruff or Seborrheic Dermatitis. This involves a lot of white fuzzy dandruff falling off the scalp and some itching. There is usually no hair loss.
The other is a deeper infection that causes severe flaking, redness, pain and itching and even hair loss and hair breaking and is called Tinea Capitis.
Tinea Capitis is much more severe than dandruff and usually has patches of clear hair loss and thickened rash. Treatment requires tablets, not just a cream, as the fungus is deeper into the hair structure and the medicine cannot reach it.
How can I treat dandruff?
Dandruff, or seborrheic dermatitis, can be treated with an antifungal shampoo such as Ketoconazole. Regular sufferers of this condition can wash their hair semi-regularly with head and shoulders shampoo (or equivalent) and ensure hair is not shampoo washed too often or too infrequently. There is a suggested guide at the end of this article about that.
The more severe fungal infection, Tinea Capitis, involves a more advanced fungal infestation either deep into the surface of the hair shaft or actually into the centre of the shaft. The hair shaft is the ‘finished product’ of the hair; it is like a tree in a way; dead cells locked together with a central space.
If the infection gets deep enough to where the hair is created, called the bulb, it can interrupt hair growth and lead to baldness. This is seen in animals as ‘mange’. The cartoon below gives an idea and the link shows some examples.
Tinea Capitis requires a number of weeks using an antifungal tablet. This may affect the liver in some people and so it is wise to get a skin scraping and hair sample to actually grow the fungus prior to a commitment of therapy. More information can be found here: https://dermnetnz.org/topics/tinea-capitis/
Following the use of the tablets, a period of months may be required prior to the new, stronger and unaffected hair to grow out.
Finally, if a scaling or flaking of the scalp cannot be diagnosed, the best way forward is to seek a specialist review or take a biopsy. Some skin conditions can affect the scalp. In the worst case scenario, they can cause scarring or damage to the structure of the skin on the scalp. This can be devastating if it permanently affects hair growth. For this reason, biopsy and aggressive treatment should not be delayed.
How do I treat an itchy scalp?
In all of these conditions, the principle is to use antifungal medication however other treatments may be useful. Keratinolytics are medications that break down the scaly top layer of the skin and may reduce flaking. Steroids often help with inflammation. Other medications for itch may be recommended. There is a steroid shampoo available which helps break down the flaking; you use it prior to putting antifungal on it.
Finally, some people find that despite their best efforts, treated Tinea Capitis or Seborrheic Dermatitis keep coming back time and time again. This can often be due to sweaty collars, humidity or other factors. Regular use of antifungal creams, shampoo regimens and hygiene are one part of therapy.
Chronic or Recurrent Fungal Scalp Infections
In all of these conditions, the principle is to use antifungal medication however other treatments may be useful. Keratinolytics are medications that break down the scaly top layer of the skin and may reduce flaking. Steroids often help with inflammation. Other medications for itch may be recommended. There is a steroid shampoo available which helps break down the flaking; you use it prior to putting antifungal on it.
Finally, some people find that despite their best efforts, treated Tinea Capitis or Seborrheic Dermatitis keep coming back time and time again. This can often be due to sweaty collars, humidity or other factors. Regular use of antifungal creams, shampoo regimens and hygiene are one part of therapy.
Chronic or Recurrent Fungal Scalp Infections
SCALP
Basic Steps
- Shampoo once or twice a week with a decolonising medicated shampoo like Head and Shoulders
- Head and Shoulders contains Zinc which removes the colonising yeast, malassezia
- Avoid using too much shampoo as it will reduce the oil protecting the scalp
- Reduce sweating if possible
Next Steps
- Once per week use of Ketoconazole shampoo (Nizoral)
- Additional Steps
- Light therapy to reduce yeast levels
- Potassium Permanganate baths
- Once monthly antifungal tablets
What is Potassium Permanganate?
A potassium permanganate (also known as Condy’s Crystals) bath or soak is an old remedy for skin infections that has enjoyed continuous use since the 1800s. Originally discovered in the 1600s, this purplish crystal came into common use to treat skin infections owing to its oxidizing properties. Currently it is on the World Health Organisation’s List of Essential Medications and is used for infected eczema, for water purification and also for superficial wounds, diabetic ulcers and tropical skin infections.
The theory behind its use in chronic or recurrent scalp infections is to decolonise the scalp on a regular basis and to inhibit the growth of fungal species. It is safe to use and generally feels quite ‘clean’. A 400mg tablet should be dissolved in every 4L of water and care must be taken not to let any concentrated solution touch the skin; it may burn.
Potassium Permanganate must NEVER be ingested and you must call an ambulance if you do so. Keep it away from children and treat it as dangerous as household bleach. It may stain the skin or clothing if too concentrated however this wears off and is rare.
There is no limit to how often potassium permanganate can be used. In addition to fungal scalp infections, potassium permanganate is often used in foot baths or spa
treatments owing to its delightful purple colour and properties against treating athlete’s foot. It may be added to aromatherapy oils in this setting. In Hong Kong’s sweatier summers, adding it to the weekly regimen might not be a bad idea.
What is Light Therapy?
Bacteria, yeast and human cells absorb and react to the electromagnetic energy of light wavelengths. Ultraviolet light ranges from 10-400 nanometers and cannot be seen by the human eye. The visible light spectrum ranges from 400 nm (blue light) to 700 nm (red light).
The particular wavelength represented by the colour, or UV band, is absorbed by the cell based on its structure. For example, Tricophyton Rubrum, a common yeast, produces a red pigment called xantomegnin which absorbs 523nm light. Once absorbed, this energy causes a chemical reaction that is toxic to the target cell, such as T. Rubrum, but not the host cell and produces the desired outcome.
Blue light and UV-A have both been associated with reduction in skin fungal infections. This is not surprising as they share similar wavelengths. By using targeted light machines rather than general sunlight, in which the UV would harm our own skin cells causing sunburn and potentially skin cancer, we can influence fungal skin infections.
To date, studies are still being pursued to identify the best method of using light. It is recommended to try 20 minutes of blue light or UV A light to the area in question three times per week and assess the outcome in 6 weeks. UV light therapy devices are commercially available however tend to be in the handheld or ‘wand’ format and are designed for psoriasis. Given the existing market for light therapy in the hair restoration and cosmetic field, there are more scalp friendly light therapy devices available for blue light devices.
REFERENCES
Wikler et al. The effect of UV-light on pityrosporum yeasts: ultrastructural changes and inhibition of growth. Acta Derm Venereol. 1990;70(1):69–71.
Pirkhammer et al. Narrow-band ultraviolet B (ATL-01) phototherapy is an effective and safe treatment option for patients with severe seborrhoeic dermatitis. Br J Dermatol. 2000 Nov;143(5):964-8.
Gavazzoni Dias et al. Update on therapy for superficial mycoses: review article. An Bras Dermatol. 2013 Sep-Oct; 88(5): 764–774.
Gwynne PJ, Gallagher MP. Light as a Broad-Spectrum Antimicrobial. Front Microbiol. 2018;9:119. Published 2018 Feb 2.
Yoshimura, M et al. Antimicrobial effects of phototherapy and photochemotherapy in vivo and in vitro. Br J Dermatol. 1996 Oct;135(4):528-32.
