Most food allergies that begin in early childhood are mild and resolve by school age, but nut allergies persist in about 80-90% of individuals into adulthood. The consumption of nuts, particularly cashew nuts, has increased dramatically in Finland in the 21st century, leading to a rise in severe allergic reactions to cashew nuts among young children. Of the food anaphylaxis cases reported in the Finnish Anaphylaxis Registry between 2015-2020, 49% were caused by nuts, with cashew nuts being the most common trigger. The standard treatment for nut allergies is strict avoidance of nuts and symptom management with emergency medications. Oral immunotherapy (OIT) is a food allergy treatment that increases tolerance, and it has primarily been studied in school-aged children, with desensitization achieved in about 80% of cases. Permanent tolerance, depending on the allergen, develops in 30-50% of cases within five years. International guidelines recommend peanut OIT for children over the age of 4 who have severe peanut allergies. The likelihood of achieving tolerance, especially permanent tolerance, appears to improve the earlier the treatment is started. To date, only one study (NUIT CRACKER) has been published on cashew nut desensitization in children over 4 years old, involving 50 children, where 88% achieved desensitization to both cashew nuts and pistachios. The aim of this study is to develop a cashew nut desensitization protocol and investigate its effectiveness in achieving tolerance and permanent desensitization in children aged 1-17 years, compared to cashew nut avoidance. The study will assess the safety of cashew nut desensitization and its impact on the quality of life of patients and their families.