The Safe and Gentle L-Tryptophan Formula. ProQuiet is helpful for maintaining a healthy nervous system and mental attitude. It has been tested and is safe and effective for use as directed. ProQuiet is safe enough to use daily or can be used as needed in stressful situations. Form: Chewable Flavored Tablet - savored by both dogs and cats. Ingredients: L-Tryptophane, Taurine, Hops, Chamomile, Brewers Yeast, Vitamin B3, Vitamin B6, Ginger, Vitamin B12, and Folic Acid.