The European Medicines Agency (EMA) has recommended restricting the use of methysergide due to concerns that it could cause fibrosis, a condition in which fibrous (scar) tissue accumulates in the body’s organs potentially damaging them.

Methysergide medicines are now only to be used for preventing severe intractable migraines and cluster headaches (a type of severe, recurring headache on one side of the head, usually around the eye) when standard medicines have failed.

In addition, treatment should only be started and supervised by a specialist doctor with experience in treating migraine and cluster headaches. Patients should also be screened for fibrosis at the start of treatment and should have additional screenings every six months. Treatment must be discontinued if symptoms of fibrosis occur.

The Agency’s Committee for Medicinal Products for Human Use (CHMP), which conducted the review, noted that these recommendations were necessary due to the reports of fibrosis seen with methysergide and other medicines of the same class (ergot derivatives). The symptoms of fibrosis often take some time to appear and without screening the diagnosis may come too late to prevent severe (and potentially life-threatening) damage to organs.

Regarding the benefits, the Committee noted that there is some evidence of a clinically relevant effect of methysergide when used for prevention in patients who regularly get migraines and cluster headaches and for whom treatment options are limited. Methysergide has also been used for treating diarrhoea caused by carcinoid disease (a slow-growing tumour that commonly affects the gut). However, there were no data to support this use and Methysergide should therefore no longer be used in carcinoid disease.

The prescribing information for physicians and information in the patients’ information leaflet will be updated. The CHMP recommendations will now be forwarded to the European Commission, which will issue a final legally-binding decision.

The Agency’s recommendations are based on available data on the benefits and risks of methysergide, from clinical studies, post-marketing safety reports and the scientific literature. Based on these data a potential causal association between methysergide and fibrosis seems likely. The mechanism by which methysergide could cause fibrosis through serotoninergic-receptor activation is widely described in the literature.