Euthyrox is manufactured by Merck KGaA, a leading science, and technology company located in Darmstadt, a city in the state of Hesse in Germany, for Provell Pharmaceuticals, LLC. Provell Pharmaceuticals is located in Honey Brook, PA, and is a small, private healthcare company specializing in the marketing and distribution of world-class leading pharmaceutical products in the United States. They hold the license to label, market, and distribute Euthyrox in the United States.

Euthyrox contains levothyroxine (also known as T4) which is a man-made form of thyroxine, a hormone that is produced naturally in the body by the thyroid gland. Euthyrox replaces missing thyroxine in people whose thyroid glands do not produce enough thyroxine naturally.

Thyroid hormones (such as thyroxine) play a vital role in our normal growth and development, and the maturation of our brain, spinal cord, nerves, and bone. Thyroid hormones help cells to function and are also involved in their breakdown. They also help regulate our moods, reproductive function, metabolism, and gastrointestinal function.

Euthyrox is generally taken life-long when used to treat hypothyroidism (low thyroid levels) unless the cause is transient.