Systemic mastocytosis is a myloproliferative neoplasm characterised by pathological proliferation of mast cells and their accumulation within one or several organs (skin, bone marrow, gastrointestinal tract, lymph nodes, the liver, and the spleen). In the clinical picture of systemic mastocytosis, symptoms resulting from the action of mediators released from stimulated mast cells and symptoms associated with tissue infiltration by mast cells play a significant role along with characteristic skin lesions. Patients complain about skin-related (pruritus, flushing), gastrointestinal (heartburn, abdominal pain, nausea, vomiting, diarrhoea), circulatory (hypotension, tachycardia, arrhythmias, syncope, headache), and respiratory symptoms (dyspnoea), as well as bone pain. A particularly dangerous, life-threatening problem is the high risk of an anaphylactic reaction. Treatment of systemic mastocytosis involves patient education with a recommendation to avoid factors that may lead to mast cell degranulation, and symptomatic and cytoreductive treatments. One of the significant problems hindering the symptomatic treatment of patients with mastocytosis is a high risk of hypersensitivity reactions after some medications commonly used in palliative care, such as nonsteroidal anti-inflammatory drugs and certain opioid receptor agonists (morphine, codeine).