Why does Faded Serum smell? Glutathione! an ingredient thats super effective at reducing the appearance of discoloration in weeks Glutathione has a cysteine chain that causes it to have a sulfur One of our products smells like rotten eggs?! It's actually because of an ingredient called Glutathione, which naturally contains Sulfur. But don't let the smell fool you this ingredient will make One of our products smells like rotten eggs?! It's actually because of an ingredient called Glutathione, which naturally contains Sulfur. But don't let the smell fool you this ingredient will make Glutathione Smell