Celecoxib (Celebrex) is a Cox 2 selective non steroidal anti-inflammatory agent. Adverse reactions reported are usually benign, such as maculopapular exanthema. However, recently severe toxiderma have started to appear. We report two patients who developed a sever celecoxib drug skin reaction. Case no 1. In a 73 year-old woman, treated with celecoxib for cervical arthralgia, a maculopapular exanthema five days after treatment was started. The exanthema, initially edematous and purpural became bullous with multi-visceral failure (disseminated intravascular coagulation, renal failure, hepatitis and pancreatic). The disease slowly regressed. Case no 2. A 72 year-old man, treated for cervicalgia with celecoxib, presented a pustular exanthema of the face and the trunk, ten days after introduction of the treatment, associated with an inflammatory syndrome and hepatic cytolysis. Within 8 days the disease had regressed. In both these patients, the celecoxib patch tests were positive. Until now, the side effects reported with celecoxib have been generally benign exanthemas. We report two cases of severe celecoxib-induced toxiderma: a hypersensitivity syndrome with multi-organ failure and an acute generalized atypical exanthematous pustulosis. These severe toxidermas have rarely been reported in the literature, but we now need to reassess the risks with these new molecules.