Syringe dosage of Rebif against injection instructions. A one month supply of Rebif can cost anywhere from $1,600 to more than $2,000 USD. Rebif is a disease-modifying drug (DMD) used to treat multiple sclerosis in cases of clinically isolated syndromes as well as relapsing forms of multiple sclerosis and is similar to the interferon beta protein produced by the human body. It is co-marketed by EMD Serono and Pfizer in the US under an exception to the Orphan Drug Act. It was approved in Europe in 1998 and in the US in 2002 and is registered in more than 80 countries worldwide. Rebif is administered via subcutaneous injection three times per week, and can be stored at room temperature for up to 30 days.