Excipient (pharmacologically inactive substance)
What is it?
Shellac is composed of hydroxyaliphatic acids and alicyclic acids. Shellac has been used in the pharmaceutical industry as a tablet coating, often for enteric coating on tablets. In the cosmetics industry, shellac has been used in mascara, hair spray, nail polish and eyeliner. Traditionally, shellac has been used in the furniture industry as a wood or paint sealant.
The median lethal dose for shellac has been found to be more than 5 grams per kilogram, many more times than what the average consumer might be exposed. Toxicity studies in animals have shown no adverse effects from oral, dermal, ocular or respiratory tract exposure to formulations containing up to 6 percent shellac. Mutagenicity, irritation, sensitization and photosensitization were not seen in clinical analysis of cosmetic formulations containing up to 6 percent shellac. However, reports from 2011 note cases of allergic contact dermatitis in the eye area of those who used certain cosmetics, such as mascara.