Peanut allergy is one of the most common types of food allergy worldwide. Although it occurs in both adults and children, it usually affects the developmental age population. Risk factors for the development of peanut allergy include coexisting atopy, particularly atopic dermatitis, sensitization to egg white, mutation in the filaggrin gene, and a family history of peanut allergy. It is currently recognized that the primary route of exposure to peanuts is important for the development of sensitization or tolerance – early oral exposure favors tolerance, while transdermal exposure the development of allergy. Most allergic children react to the first oral exposure to the allergen, even if they have not previously consumed it. Symptoms after peanut ingestion develop similarly to those in a typical IgE-mediated reaction, i.e., within seconds to 2 h after contact with the allergen. Although most symptoms after peanut ingestion are mild, peanut consumption is one of the main causes of potentially life-threatening allergic reactions. Peanut allergy is an example of a persistent food allergy, and long-term observational studies indicate that only a small proportion of children with this allergy acquire tolerance.