Anaphylactic reactions from foods and drugs in patients with systemic mastocytosis (SM) appear to be less common than previously thought, according to a recently published study in The Journal of Allergy and Clinical Immunology: In Practice.
The study results challenge recommendations, common in patient support groups and on internet forums, that people with SM should avoid certain foods and drugs.
What is SM?
Systemic mastocytosis (SM) is a rare hematological disease characterized by mast cells that are overactive and accumulate in different parts of the body such as the bone marrow, liver, spleen, gastrointestinal tract and lymph nodes.
“Our results do not support general elimination diets or drug avoidance in [mastocytosis] patients without a history of [drug hypersensitivity] or [food hypersensitivity], although it may be advisable to give the first tablet of a not previously tolerated NSAID under medical supervision,” the authors said.
Read more about SM signs and symptoms
Study authors performed a retrospective analysis of medical electronic records from 2002 to 2022 to detect patients with SM and suspected food or drug allergies who underwent an oral challenge test (OCT).
OCTs are diagnostic procedures in which patients with suspected food or drug allergies are given increasing amounts of the suspected allergen until a reaction occurs or the patient consumes the total dose.
Researchers identified 83 patients who underwent OCTs. Combined, the 83 patients underwent more than 400 OCTs for drugs, alcohol, foods and food additives. Only 10 OCTs led to an anaphylactic reaction, representing about 2.25% of the sample. Four reactions were due to drugs, and six were due to food.
The reactions were mostly subjective: itching, heat sensation and dizziness. The study also observed subjective symptoms in OCTs performed with a placebo, calling into question the relevance of some of the reactions recorded in the study.
There was a correlation between some patient characteristics and anaphylactic reactions, namely higher serum tryptase and the density of mast cells in the bone marrow.
Because substances released by mast cells during degranulation are key mediators in anaphylactic responses, patients with SM tend to have a greater risk of anaphylaxis than the general population. Although most anaphylactic reactions in patients with SM are due to insect venom, reactions against foods and drugs are also likely.
This phenomenon has led to recommendations to avoid certain foods and drugs among people with SM.
