Liquid Magnesium 400 mg by Carlson Labs is often taken to reduce pains that are felt in the body. These could be the result of pulled muscles. arthritis or other injuries. It is a supplement that can be taken to increase the energy levels in the body. Liquid Magnesium 400 mg by Carlson Labs often decreases some of the symptoms that are associated with aging. The supplement can relieve symptoms of stress. such as headaches. It can be taken to relieve cramps that are felt in the muscles and pain from fibromyalgia. Liquid Magnesium 400 mg by Carlson Labs is a product that works from the inside of the cells. It protects the cells and provides the support that is needed to the brain. blood vessels and the heart.