Using Gemcal Nasal Spray and Shelcal HD together is generally considered safe when taken as prescribed, as they work in different ways: Gemcal helps regulate and lower the calcium released from bones, while Shelcal HD provides calcium and vitamin D to support bone health. However, since both can affect calcium levels in the body, combining them without medical advice may increase the risk of imbalance. It’s best to consult your doctor before using them together, especially if you have any underlying health conditions or concerns about calcium levels. Your doctor can determine the correct dose and monitor your calcium levels if needed.