The most important side effects with Jayempi include bone marrow depression (a condition in which the bone marrow cannot make enough blood cells) that most frequently manifests as leucopenia (low white blood cell counts) and thrombocytopenia (low blood platelet counts); viral, fungal and bacterial infections; life-threatening liver injury; hypersensitivity (allergic reaction), Stevens-Johnson syndrome and toxic epidermal necrolysis (life-threatening reactions with flu-like symptoms and painful rash and blistering in the skin, mouth, eyes and genitals).

Jayempi must not be used in people allergic to the active substance azathioprine, to 6-mercaptopurine or to any of the other ingredients. Patients must not be given any live vaccine, especially the BCG, smallpox and yellow fever vaccines, until at least 3 months after the end of treatment with azathioprine. Jayempi must not be used in breastfeeding women.

For the full list of side effects and restrictions of Jayempi, see the package leaflet.