<<Disclaimer: Verify this information before applying it to your situation.>> While we're on the subject of medications...Not all potassium preparations are gluten-free. When I was first diagnosed the hospital gave me this nice packet of potassium to mix in water & I got sicker than a dog. The hospital pharmacist checked & sure enough, the filler is a mixture of cereal grains. I think this is true of most, if not all, of the prescription potassium that comes in the powder form. BTW, K- Dur is GF, if any one ever finds they need a prescription potassium supplement. Kate in VA