De mest almindelige bivirkninger ved Rebif (der ses hos flere end 1 ud af 10 patienter) er influenzalignende symptomer, neutropeni, lymfopeni og leukopeni (lavt antal hvide blodlegemer), trombocytopeni (lavt antal blodplader), anæmi (lavt antal røde blodlegemer), hovedpine, betændelse og andre reaktioner på injektionsstedet samt forhøjede leverenzymer (transaminaser).
The most common side effects with Rebif (seen in more than 1 patient in 10) are flu-like symptoms, neutropenia, lymphopenia and leucopenia (low white blood cell counts), thrombocytopenia (low blood platelet counts), anaemia (low red blood cell counts), headache, inflammation and other reactions at the injection site, and increases in transaminases (liver enzymes).