Coal Tar Shampoos

What is a coal tar shampoo?

A coal tar shampoo is a shampoo with coal tar added as an active ingredient.

Coal Tar is a much loved, much used active ingredient that has been used Coal tar has been used medicinally for thousands of years.  It contains over 10,000 chemicals [8], of which opnly 50% have been identified [9].

The ingredient itself is a by-product of coal, created by distilling coal at extremely high temperatures.  The resulting crude coal tar is a dark brown thick liquid with a “characteristic” odor (it stinks basically).

Included on the WHO Model List of Essential Medicines, it is considered an important healthcare agent and has been for many years. It is one of only two ingredients approved by the USFDA for over the counter treatment of psoriasis.  It’s also a NICE recommended first-line treatment for psoriasis in the UK.

How do coal tar shampoos work?

How coal tar reduces symptoms of psoriasis and seborrheic dermatitis is not completely understood.

Coal Tar is keratolytic that works by slowing the growth of skin cells to help your skin shed dead cells from its top layer  – the keratoplastic.

It has proven anti-fungal [1] properties, antiseptic properties, anti-inflammatory [2] properties and it also seems to normalize keratin growth on the skin and reduce the formation of scales.

We have compiled a full article on coal tar if you want to read more of this unique ingredient.

What is a coal tar shampoo made of?

Coal Tar is added to shampoos in two forms; crude or in a solution.

Crude or raw coal tar is generally considered the most effective form of the substance.  However, many shampoos these days use a coal tar extract. This refined form of coal tar is cleaner, doesn’t smell as bad, is more practical for home use but symptom improvement may take longer.

It’s quite often in shampoos these days to see coal tar mixed with other ingredients e.g. Salicylic Acid to enhance their performance.

The FDA maintains that OTC products with coal tar concentrations between 0.5 percent and 5 percent are safe.  This is crude coal tar – manufacturers will often have to add 5 times that amount of coal tar solution for it to be as effective as crude coal tar. Psoriatrax, for example, add 25% Coal Tar Solution and label that as equivalent to 5% Coal Tar.

It is worth noting that stronger isn’t necessarily better when it comes to a coal tar shampoo. Quite the opposite in fact. A recent study suggests that a 1% coal tar solution is more effective than a 5% solution when treating mild to moderate psoriasis [3].

Are there any side effects from using a coal tar shampoo?

Although most people do not experience significant side effects, the WHO state that coal tar shampoos may cause skin irritation and on rare occasions allergic sensitization is possible.   They also recommend that a coal tar shampoo should not be applied to inflamed, broken or infected skin.

Because coal tar can increase sensitivity to sunlight, skin treated with coal tar products should be protected from ultraviolet rays to avoid irritation and sunburn. The American Academy of Dermatology recommends that you protect your scalp from the sun by wearing a hat when outdoors and seeking shade whenever possible if you use a coal tar shampoo.

The same organization advises that tar shampoos can discolor blonde, grey or light-colored hair.

Are coal tar shampoos cancerous?

There’s been a number of controversies over coal tar in recent decades.

Coal tar contains as many as 10,000 different chemicals, but only about half of these have actually been identified. Many people have expressed concern over the unknown components that could be potential carcinogens or cancer-causing substances.

In the 1990s, studies appeared apparently linking coal tar exposure to cancer in animals [4].  A number of countries including the EU, China and Taiwan banned the use of coal tar in cosmetics as a result of these findings.

Polytar, one of the most popular coal tar shampoos at that time, was completely withdrawn. Coal tar shampoos started to disappear from the shelves.

However further research found that coal tar in low doses wasn’t linked to cancer [5][6].

This prompted the EU to overturn their own ruling.  The FDA maintains that there is no scientific evidence that the tar in OTC products is carcinogenic.

Despite its 75-year history of documented use without any clear evidence of increased cancer risk in low doses, some skepticism remains. Formulations containing more than five percent crude coal tar are listed as carcinogenic by the World Health Organization. California still insist that coal tars treatments are labeled, Warning: This product contains chemicals known to the state of California to cause cancer.

Some of the controversies may be related to the questionable safety of using coal tar in the production of sealant products [10] and in other industrial settings; these problems are not relevant to the use of weak coal tar solutions in shampoo formulations.

How effective is a coal tar shampoo at treating psoriasis?

Psoriasis.org explains that psoriasis is a condition of the immune system that can cause skin symptoms like itching, flaking, scaling and a rapid build-up of skin cells that creates raised plaques. The use of a coal tar shampoo can reduce inflammation and slow the growth of skin cells to restore the skin’s normal appearance while helping to reduce uncomfortable symptoms.

Despite its age, coal tar remains extremely popular and effective for sufferers of mild to moderate scalp psoriasis. There are steroid treatments available on prescription but the popularity of coal tar never seems to wane. The effects of coal tar on psoriasis may even be enhanced when the substance is used in conjunction with ultraviolet light therapy.

How effective is a coal tar shampoo at treating seborrheic dermatitis?

Although the root cause of Seborrheic Dermatitis is still unknown, recent research [7] suggests seb derm to be associated with a type of fungus called Malassezia furfur. Symptoms include itching, scaling, rash and ring-shaped patches of dry, pink skin. The antifungal properties of coal tar are believed to be the primary reason that it reduces symptoms of the common skin condition. In a clinical study [1], coal tar demonstrated its ability to inhibit the growth of 52 Malassezia strains.

However, there are other more modern treatments for seb derm which seem to be more precise and more effective at combatting the symptoms associated with seb derm. Piroctone Olamine, Ketoconazole and Selenium Sulfide are three active ingredients that tend to be more widely used in recent years.

References

[1] Nenoff, P., Haustein, U. F., & Fiedler, A. (1995). The antifungal activity of a coal tar gel on Malassezia furfur in vitro. Dermatology, 191(4), 311-314.

[2] Zeichner, J. A. (2010) Use of Topical Coal Tar Foam for the Treatment of Psoriasis in Difficult-to-treat Areas. J Clin Aesthet Dermatol. 2010 Sep; 3(9): 37–40.

[3] Goodfield M1, Kownacki S, Berth-Jones J. (2004) Double-blind, randomised, multicentre, parallel group study comparing a 1% coal tar preparation (Exorex) with a 5% coal tar preparation (Alphosyl) in chronic plaque psoriasis. J Dermatolog Treat. 2004 Jan;15(1):14-22.

[4] Pion IA, Koenig KL, Lim HW. (1995) Is dermatologic usage of coal tar carcinogenic? A review of the literature. Dermatol Surg. 1995 Mar;21(3):227-31.

[5] Roelofzen JH, Aben KK et al. (2010) No increased risk of cancer after coal tar treatment in patients with psoriasis or eczema. J Invest Dermatol. 2010 Apr;130(4):953-61. doi: 10.1038/jid.2009.389. Epub 2009 Dec 17.

[6] Cosmetic Ingredient Review Expert Panel. Final safety assessment of Coal Tar. Int J Toxicol. 2008;27 Suppl 2:1-24. doi: 10.1080/10915810802244405.

[7] Thomas Berk, MD and Noah Scheinfeld, MD. Seborrheic Dermatitis. (2010) P T. 2010 Jun; 35(6): 348–352.

[8]  N.J. Lowe  J. Breeding  M.S. Wortzman The pharmacological variability of crude coal tar (1982)

[9] G. Maiganga et al. Physicochemical Characterization of Coal Tar Produced by Pyrolysis of Coal (2017) Journal of Minerals and Materials Characterization and Engineering

Vol.05 No.05(2017), Article ID:78984

[10] B. J. Mahler et al.  Coal-Tar-Based Pavement Sealcoat and PAHs: Implications for the Environment, Human Health, and Stormwater Management. (2012) Environ Sci Technol. 2012 Mar 20; 46(6): 3039–3045.