Move over salicylic acid -- there is a new active contending for the as difficult to formulate with as it is effective medal -- azelaic acid.

It doesn't dissolve in water. It doesn't dissolve in oil. It crystalizes out of most solutions once any amount of water is added. Oh my!

This is my first working product with azelaic acid. It seems quite stable and it has been effective for my use.

More information about azelaic acid:

• https://pubmed.ncbi.nlm.nih.gov/2530163/
• https://jddonline.com/articles/azelaic-acid-evidence-based-update-on-mechanism-of-action-and-clinical-application-S1545961615P0964X/
• https://www.sciencedirect.com/topics/medicine-and-dentistry/azelaic-acid

Formula is available in spreadsheet form here.

Notes:

• Ethanol 50% is literally 100 proof vodka. Use the cheapest kind available (non-flavored, obviously)
• Make sure the container remains sealed when not in use
• Due to lack of water content and high alcohol content additional preservative is not required
• This formula is provided for information purposes. Use of any product containing strong actives incurs risk. Consult a medical professional before use.

Directions:

Mix ingredients until powder is dissolved. Apply moderate heat if necessary. Store in air-tight container.