Undecylenic Acid USP: Undecylenic Acid USP inhibits fungal growth effectively. It provides relief from itching, burning, irritation, soreness, redness, scaling, and discomfort. Derived from castor oil and found in human sweat, this compound is versatile. Dosage forms include powder (10%, 12%, 19%), topical solution/spray (25%), cream (20%), ointment (25%), and soap bars weighing 97.5g. This acid works well against toenail fungus by preventing the fungi from growing further. Many over-the-counter medications use undecylenic acid due to its powerful anti-fungal properties. If you suffer from conditions like ringworm or jock itch, products containing undecylenic acid can bring quick relief.