Serene-um Drops are suitable for cats & dogs. They are a natural way to help prevent travel sickness, calm nervous, anxious or aggressive pets. They are easy to give with no mess and no waste. Size: 100ml Active Ingredients: L-TRYPTOPHAN - Essential Amino Acid And A Precursor To Serotonin, The Neurotransmitter Involved In Mood And Sleep Regulation. Promotes Natural Feelings Of Satiation And Contentment B-VITAMINS - Work Together To Ease Anxiety And Promote A Healthy Nervous System TAURINE - Essential Amino Acid For Cats To Ensure Healthy Eyesight And Heart VITAMIN E - Natural Antioxidant SELENIUM - Promotes A Healthy Immune System.