Using 3% 1,2-Hexanediol as Sole Preservative in a Serum Formula

Question

Can 3% [url=http://www.myskinrecipes.com/shop/%E0%B8%95%E0%B8%B1%E0%B8%A7%E0%B8%97%E0%B8%B3%E0%B8%A5%E0%B8%B0%E0%B8%A5%E0%B8%B2%E0%B8%A2/886-1-2-hexanediol.html:35312pnd]1,2-Hexanediol[/url:35312pnd] be used as the sole [url=http://www.myskinrecipes.com/shop/34-%E0%B8%AA%E0%B8%B2%E0%B8%A3%E0%B8%81%E0%B8%B1%E0%B8%99%E0%B9%80%E0%B8%AA%E0%B8%B5%E0%B8%A2:35312pnd]preservative[/url:35312pnd] in a formula? I've seen information saying it can be used, but I'm unsure if it's sufficient to control microbial growth, especially since I'm often sensitive to [url=http://www.myskinrecipes.com/shop/34-%E0%B8%AA%E0%B8%B2%E0%B8%8A%E0%B8%A3%E0%B8%81%E0%B8%B1%E0%B8%99%E0%B9%80%E0%B8%AA%E0%B8%B5%E0%B8%A2:35312pnd]preservatives[/url:35312pnd] and am particularly concerned about using them. Here is the formula, using recommended percentages: 1. DI Water, 2. [url=http://www.myskinrecipes.com/shop/whitening-%E0%B8%AA%E0%B8%B2%E0%B8%A3%E0%B9%83%E0%B8%AB%E0%B9%88%E0%B8%9C%E0%B8%B4%E0%B8%A7%E0%B8%82%E0%B8%B2%E0%B8%A7/1140-tranexamic-acid-%E0%B8%97%E0%B8%A3%E0%B8%B2%E0%B9%80%E0%B8%99%E0%B8%8B%E0%B8%B2%E0%B8%A1%E0%B8%B4%E0%B8%84-%E0%B9%81%E0%B8%AD%E0%B8%8B%E0%B8%B4%E0%B8%94.html:35312pnd]Tranexamic Acid[/url:35312pnd], 3. [url=http://www.myskinrecipes.com/shop/whitening-%E0%B8%AA%E0%B8%B2%E0%B8%A3%E0%B9%83%E0%B8%AB%E0%B9%88%E0%B8%9C%E0%B8%B4%E0%B8%A7%E0%B8%82%E0%B8%B2%E0%B8%A7/1213-4msk-potassium-methoxysalicylate.html:35312pnd]4MSK[/url:35312pnd], 4. [url=http://www.myskinrecipes.com/shop/%E0%B8%A1%E0%B8%AD%E0%B8%A2%E0%B8%8B%E0%B9%8C%E0%B9%80%E0%B8%88%E0%B8%AD%E0%B8%A3%E0%B9%8C/404-double-hyaluron-liquid.html:35312pnd]Hyaluronic Acid[/url:35312pnd] (china), 5. [url=http://www.myskinrecipes.com/shop/%E0%B8%AA%E0%B9%88%E0%B8%A7%E0%B8%99%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%81%E0%B8%AD%E0%B8%9A%E0%B9%80%E0%B8%84%E0%B8%A3%E0%B8%B7%E0%B9%88%E0%B8%AD%E0%B8%87%E0%B8%AA%E0%B8%B3%E0%B8%AD%E0%B8%B2%E0%B8%87%E0%B8%84%E0%B9%8C/143-glycerin-%E0%B8%81%E0%B8%A5%E0%B8%B5%E0%B9%80%E0%B8%8B%E0%B8%AD%E0%B8%A3%E0%B8%B5%E0%B8%99.html:35312pnd]Glycerin[/url:35312pnd], 6. [url=http://www.myskinrecipes.com/shop/%E0%B8%95%E0%B8%B1%E0%B8%A7%E0%B8%97%E0%B8%B3%E0%B8%A5%E0%B8%B2%E0%B8%A2/886-1-2-hexanediol.html:35312pnd]1,2-Hexanediol[/url:35312pnd].

MySkinRecipes Expert · Accepted Answer

Using 1,2-Hexanediol as a Sole Preservative

Regarding your question about using 3% 1,2-Hexanediol as the sole preservative in your formula, based on the information available:

1,2-Hexanediol is not technically classified as a traditional preservative but has strong antimicrobial properties and acts as a preservative booster.
At a concentration of 3%, it has been shown in challenge tests to effectively control bacteria (meeting EP level A standards).

While 3% 1,2-Hexanediol provides significant antimicrobial activity, it is often recommended to use it in combination with a small amount of another broad-spectrum preservative to ensure comprehensive protection against a wider range of microorganisms, including yeast and mold, over the product's shelf life. This is especially important for water-based formulas containing ingredients like Hyaluronic Acid and Glycerin, which can be prone to microbial growth.

Given your sensitivity to preservatives, using 3% 1,2-Hexanediol as a booster allows you to significantly reduce the concentration of traditional preservatives, potentially minimizing the risk of irritation while maintaining microbial stability. For example, combining 3% 1,2-Hexanediol with a very low percentage of a gentle, broad-spectrum preservative might be a suitable approach.

If you choose to use 3% 1,2-Hexanediol as the sole antimicrobial agent, it is highly recommended to perform a challenge test on your specific formula to confirm its efficacy and ensure the product remains microbially stable throughout its intended shelf life.

Your formula includes: