This study reports a 12-year-old girl who developed an anaphylactic reaction following snail ingestion during house dust mite (HDM) immunotherapy treatment. Radioallergosorbent (RAST) inhibition showed cross-reactivity between the two allergens, leading to consideration of HDM as the sensitizing agent. Children undergoing HDM immunotherapy treatment should be aware of the potential risks of hypersensitivity reactions to invertebrate foods.