Provided herein are compositions comprising disodium levofolinate. Also provided are processes for preparing compositions comprising disodium levofolinate. Also provided are compositions comprising disodium levofolinate prepared by the processes provided herein. Also provided are methods of treating folic acid deficiency in a subject in need thereof, comprising administering a composition provided herein to the subject. Also provided are methods of treating cancer in a subject in need thereof, comprising administering 5-fluorouracil and a composition provided herein to the subject. Also provided are methods of reducing the immediate toxic effects of methotrexate overdose in a subject in need thereof, comprising administering a composition provided herein to the subject. Also provided are methods of treating cancer in a subject in need thereof, comprising administering high-dose methotrexate and a composition provided herein to the subject. Also provided are methods of treating megaloblastic anemia in a subject in need thereof, comprising administering a composition provided herein to the subject.