Zinc Pyrithione and Dandruff

Disclaimer: 

We are not medical professionals and you should always consult a GP or specialist for advice on treating Dandruff or skin conditions. However, it is also worth noting that getting a doctors appointment for anything serious is hard enough and so the chances of being able to ask them about Dandruff is quite unlikely. Also, there is a lot of conflicting advice about Dandruff treatment online. So that is why Hairetic are here, please read through all our research and make your own decisions for your own hair and scalp health. Then make sure you see a doctor if you can.

What is Zinc Pyrithione?

Zinc pyrithione is an active ingredient commonly used in anti-dandruff shampoos and treatments. It is known for its antifungal and antibacterial properties, making it effective in treating dandruff caused by fungal overgrowth on the scalp. While the ingredient has been used for decades in the treatment of Dandruff, it is only recently coming under scrutiny from cosmetic regulators as tests have shown it can be harmful

Is Zinc Pyrithione Safe?

The European Union has now banned Zinc Pyrithone (since March 2022) for use in cosmetics products, with the UK implementing their own ban on October 15th 2022. The approach taken by the EU is that the ingredient has a risk under reproductive toxicity (meaning the ingredient could harm the health of babies developing within the womb). However, the EU also agreed Zinc Pyrithione is not harmful when used in concentrations up to 1%.

However, as Zinc Pyrithione is harmful and a controlled substance, the guidance from the EU was to ban the ingredient if an alternative was available. Which it is. There are numerous alternatives that Hairetic have looked into that are at least as effective, and less harmful.

What is slightly concerning is that the EU carried out animal testing on the ingredient to assess its toxicity. This is against the EU's own rules on testing cosmetic products on animals, but apparently, because they test's weren't specifically looking at the cosmetic safety of the product, they deemed them okay to do.

You can read about the tests done on rats, rabbits and guinea pigs done here that were used for the toxicity testing of Zinc Pyrithione here. 

So thanks to the torture of a few animals by the EU (but not specifically for cosmetic approval), we can now say with confidence that Zinc Pyrithione is highly toxic, but probably okay in shampoo up to 1% concentration, but still worth banning anyway because there are less toxic alternatives out there.

If you live in the United States you will notice that Head & Shoulders still used Pyrithione Zinc in its formulations, because despite being better alternatives available, and despite it being banned in Europe, it is a very cheap ingredient. And it has not been banned by the FDA, who take a far more liberal approach to consumer safety than the EU.

So in summary is Zinc Pyrithione safe? No. It damages the environment, causes fertility issues and is harmful to aquatic organisms.

Should you use it in shampoo as an anti-dandruff treatment? Yes, if you can't afford anything less toxic. And you live in the USA. It is still the first recommendation for treating Dandruff on the NHS website (despite being banned in the UK):

NHS website is recommending Anti-Dandruff products that are banned

How Does Zinc Pyrithione Work?

Zinc pyrithione works by slowing down the growth of yeast (Malassezia) on the scalp, which is one of the primary causes of dandruff. It also helps to reduce the production of excess skin cells, which can contribute to flaking and itching.

Benefits of Zinc Pyrithione for Dandruff

  • Antifungal activity: Zinc pyrithione effectively targets one of the fungi responsible for dandruff, helping to eliminate the underlying cause of the condition.
  • Reduction of symptoms: By controlling fungal growth and regulating skin cell turnover, zinc pyrithione helps alleviate itching, flaking, and inflammation associated with dandruff.
  • Mild and gentle: Zinc pyrithione is generally well-tolerated by most individuals and is suitable for regular use without causing scalp irritation or dryness.

How to Use Zinc Pyrithione for Dandruff Treatment

Zinc pyrithione is commonly found in shampoos and scalp treatments formulated specifically for dandruff. It is typically recommended to use these products 2-3 times per week for best results. It is important to follow the instructions provided on the product packaging and consult with a dermatologist if you have any concerns or experience any adverse reactions.

Different hair types may respond differently to treatment with Zinc Pyrithione, and the other ingredients in the shampoo might also have a big impact on how the overall product performs.  

Potential Side Effects of Zinc Pyrithione

While zinc pyrithione is generally safe for most people's scalps when used in low concentrations some individuals may experience mild side effects such as scalp irritation or dryness, especially with prolonged or frequent use. These side effects are usually temporary and can be alleviated by reducing the frequency of use or discontinuing the product. It is essential to consult with a healthcare professional if you experience severe irritation or allergic reactions.

And be aware of the more longer term side effects to both yourself and the environment through the use of this ingredient. It has been banned in Europe for a reason, and whilst this may be overly cautious compared to the opinion of the FDA, there is mounting evidence to suggest using an alternative.

List of Clinical Studies on Zinc Pyrithione for Dandruff Treatment

  1. The antifungal mechanism of action of zinc pyrithione.
    N.L. Reeder, J. Xu, R.S. Youngquist, J.R. Schwartz, R.C. Rust, C.W. Saunders, The antifungal mechanism of action of zinc pyrithione, British Journal of Dermatology, Volume 165, Issue s2, 1 October 2011, Pages 9–12, https://doi.org/10.1111/j.1365-2133.2011.10571.x
  2. Embryotoxicity of Zinc Pyrithione, An Antidandruff Chemical, in Fish Kouichi Goka, Environmental Research, Volume 81, Issue 1, 1999, Pages 81-83, ISSN 0013-9351, https://doi.org/10.1006/enrs.1998.3944.
  3. The effects of a shampoo containing zinc pyrithione on the control of dandruff, R. MARKS, A.D. PEARSE, A.P. WALKER,  British Journal of Dermatology, Volume 112, Issue 4, 1 April 1985, Pages 415–422, https://doi.org/10.1111/j.1365-2133.1985.tb02314.x
  4. A Multicenter Randomized Trial of Ketoconazole 2% and Zinc Pyrithione 1% Shampoos in Severe Dandruff and Seborrheic Dermatitis. Claudine Piérard-Franchimont, Véronique Goffin, Jacques Decroix, Gérald E. Piérard;  Skin Pharmacology and Applied Skin Physiology 1 December 2002; 15 (6): 434–441. https://doi.org/10.1159/000066452
  5. Effect of zinc pyrithione shampoo treatment on skin commensal Malassezia, Cheryl Leong, Joyce Wang, Min Jet Toi, Yuen In Lam, Joleen PZ Goh, Shi Mun Lee, Thomas L Dawson, Medical Mycology, Volume 59, Issue 2, February 2021, Pages 210–213, https://doi.org/10.1093/mmy/myaa068