Phosphorus is the second most plentiful mineral in your body. The first is calcium. Your body needs phosphorus for many functions, such as filtering waste and repairing tissue and cells. Most people get the amount of phosphorus that they need through their daily diets. In fact, it’s more common to have too much phosphorus in your body than too little. Kidney disease or eating too much phosphorus and not enough calcium can lead to an excess of phosphorous. However, certain health conditions (such as diabetes and alcoholism) or medications (such as some antacids) can cause phosphorus levels in your body to drop too low. Phosphorus levels that are too high or too low can cause medical complications, such as heart disease, joint pain, or fatigue.