Copper (citrate) is a dietary supplement that aids in the activation of enzymes involved in energy metabolism. Copper may also aid in iron absorption, which aids in the formation of hemoglobin and red blood cells. Iron is needed for healthy blood production. Copper (citrate) is used to treat or prevent abnormal heartbeats called arrhythmias. It works by slowing down the rate at which the body absorbs calcium from your stomach and intestines. This reduces the amount of calcium in your bloodstream and decreases the risk of having a heart attack or stroke. Taking too much copper can be just as dangerous as taking too much iron. Your body can't handle more than 2 mg of copper per day. If you take more than this amount over time, it can cause serious problems with your liver and kidney function. The same goes for iron; if you take too much, it can cause brain damage and death. There are several forms of copper available including copper gluconate, copper glycine, copper hydroxide, copper oxide, and copper tartrate. Each form has its own advantages depending on how you will be using it. For example, copper gluconate is not as effective as other forms of copper for treating arrhythmias because it cannot be absorbed into your bloodstream until it has been dissolved in water.