Glutathione is the body's primary internal antioxidant, made using the amino acid cysteine, and it helps protect cells from oxidative stress. Beyond detoxification, research shows glutathione is involved in thyroid hormone metabolism, Levothyroxine (Synthroid, Tirosint, Levoxyl) is a medication for treating hypothyroidism (underactive thyroid), a condition that is more common in people with Down syndrome. Health care providers usually recommend taking levothyroxine with water Is it safe to take levothyroxine and glutathione together? Levothyroxine Alternatives: What Can I Take Instead of Levothyroxine