Background Multiple sclerosis (MS) involves an immune mediated process in which an abnormal response of the body’s immune system is directed against the central nervous system. For years, MS has been treated only with intravenous drugs. For this reason, oral drugs represent a treatment breakthrough: they promote patient satisfaction and increase therapeutic compliance.

Dimethyl fumarate (DMF) is an oral drug indicated for the treatment of adult patients with relapsing remitting MS.

Purpose To evaluate the side effects and dose reduction or discontinuation of DMF in a tertiary hospital compared with those published in the product information.

Material and methods Observational, retrospective study of all patients with MS treated with DMF for at least 2 months in our hospital.

Data collected, obtained from the electronic medical history, were demographics, date of diagnosis, previous treatments, DMF start date, side effects and dose reduction or treatment discontinuation.

Results The study included 87 patients (67.7% females), mean age 39.4 years (16–56). Previous treatments used were 67.4% interferon beta-1a, 12.2% glatiramer acetate injection, 11.2% interferon beta-1b, 6.1% natalizumab and 3.1% fingolimod.

Concerning side effects, 48.3% of patients experienced flushing and 29.8% gastrointestinal events. In the majority of patients who experienced flushing, it was mild or moderate in severity. Other adverse reactions were pruritus and lymphopenia in 5.7% of patients, an increase in mean eosinophil counts and tingling sensations in 2.3% and an increase in transaminase levels in 1.1%.

Of the 87 patients, 9 experienced a dose reduction caused by the undesirable effects and 1 had to discontinue the treatment due to an increase in transaminase levels.

Conclusion

1. Our results agree with those reported in the product information, but on a higher level. Furthermore, cases of tingling were detected, which have not yet been described.

2. Although most patients had side effects at the start of therapy with DMF, only 1 patient had to discontinue treatment.

3. Gastrointestinal symptoms and flushing events were the most common adverse reactions and could be controlled by taking proton pump inhibitors and acetylsalicylic acid.

References and/or Acknowledgements Summary of Product Characteristics.

No conflict of interest.