Patients with mastocytosis often suffer from associated symptoms such as nausea, vertigo, fatigue, urticaria, abdominal cramps, diarrhea or hypotension due to release of mediators by mast cells. These patients have also an increased frequency of anaphylactic/anaphylactoid reactions due to allergens such as hymenoptera or nonspecific stimuli such as contrast media, local anesthetics or analgesics. In addition, there is increased osteoporosis in mastocytosis patients due to the activity of mast cell mediators on osteoblasts and osteoclasts. Symptoms of mastocytosis respond poorly to treatment with antihistamines or other antiallergic drugs. There is currently no specific treatment for this disease with the exception of rare cases. There are, however, some case reports suggesting that omalizumab might decrease symptoms including hypotensive events.