This is an open label observational single center study of clinical food oral immunotherapy outcomes with biomarker samples and participant and/or caregiver-completed questionnaires in participants between 6 months and 65 years of age with IgE-mediated peanut allergy undergoing food oral immunotherapy.

In this research study the investigators want to learn more about the experience of participants with peanut allergy and their caregivers undergoing food oral immunotherapy (OIT) for peanut allergy. Food oral immunotherapy (OIT) is a treatment for individuals with a food allergy to reduce the body's allergic response to the food allergen, resulting in fewer symptoms. The treatment is also called desensitization. An individual becomes desensitized to the food allergen by ingesting small amounts of the food that are slowly increased. Over time, this helps the body's immune system become used to the food so that it no longer causes an allergic reaction. By desensitizing to peanut, it may lower the risk of life-threatening allergic reactions and cause a decreased sensitivity to peanut. The investigators specifically want to learn more about the effects of food OIT on quality of life and other outcomes important to participants with peanut allergy and their caregivers and to ultimately develop tests to predict who may respond favorably to food OIT.

Inclusion Criteria:

• Individuals between 6 months and 65 years of age with a diagnosis of immunoglobulin E (IgE)-mediated peanut allergy and their caregivers; a diagnosis of IgE-mediated peanut allergy is defined by: (1) documented history of peanut allergy or determined to be allergic by oral food challenge; (2) evidence of peanut-specific IgE by either: positive skin prick test to peanut allergen (reaction wheal at least 3 mm larger than saline control) or serum peanut-specific IgE > 0.34 kilo-unit/liter (kU/L) or international unit/milliliter (IU/mL) at screening visit
• Referral by Massachusetts General Hospital (MGH) allergist for food oral immunotherapy
• Willing to sign informed consent or whose caregiver is willing to sign the informed consent (age appropriate)
• Willing to sign the assent form, if age appropriate

Exclusion Criteria:

• History of severe or life-threatening episode of anaphylaxis or anaphylactic shock within 60 days of screening
• Severe or poorly controlled asthma
• Diagnosis of other severe or complicating medical problems, including autoimmune or chronic immune inflammatory conditions or gastrointestinal inflammatory conditions, such as inflammatory bowel diseases and eosinophilic gastrointestinal disorders
• Current use of beta blocker medication(s)
• Inability to cooperate with and/or perform oral food challenge procedures
• Females who are pregnant, planning to become pregnant, or breastfeeding
• Investigator determination of safety concern for any reason

Pediatric and adult individuals with food allergy as specified in the eligibility criteria.