Peanut allergy is one of the most life-altering diagnoses in paediatric medicine. Affecting roughly 2 to 3 percent of children in Canada, with most cases persisting into adulthood, it shapes how families eat, travel, send their kids to school, and plan for emergencies. For most of the past several decades the only management was strict avoidance and an EpiPen. That is no longer the only option.
The old paradigm — and its limits
Strict avoidance plus epinephrine auto-injectors works well when everything goes right. It does not, however, change the underlying allergy. The patient remains exquisitely sensitive, and an accidental exposure — a misread label, a contaminated kitchen, a well-meaning friend — can still produce anaphylaxis. The lifetime risk of accidental reaction is non-trivial.
What oral immunotherapy actually does
Oral immunotherapy (OIT) is the gradual reintroduction of the food allergen in tiny, escalating doses under medical supervision, with the goal of raising the patient's reaction threshold. The mechanisms involve modulation of the IgE-driven response and the development of regulatory T cells specific to the allergen. The clinical effect is desensitisation — a meaningfully higher amount of peanut protein required to trigger a reaction.
Two outcomes are described:
- Desensitisation — the patient tolerates a maintenance dose of peanut as long as they continue daily dosing. Accidental exposures are far less likely to produce reactions.
- Sustained unresponsiveness — in a subset of patients, tolerance persists for some period off the maintenance dose. The duration of this state is still being characterised.
OIT is not a cure. Most patients are expected to continue some form of regular peanut exposure to maintain protection.
The process
Although programmes differ, the typical structure is:
- Pre-OIT assessment. Confirmation of the allergy by history, specific IgE, and where appropriate, supervised oral food challenge. Discussion of risks, alternatives, and family commitment.
- Initial dose escalation. Usually a single day in clinic, where the patient receives sequentially larger doses of peanut protein under physician observation, starting at fractions of a milligram.
- Build-up phase. Every 2 weeks, the patient returns to clinic for a supervised dose increase. Between visits, the same dose is taken daily at home. This phase typically lasts 6 to 12 months.
- Maintenance phase. Once the target maintenance dose is reached (often equivalent to one or two peanuts daily), the patient continues this dose indefinitely or until otherwise directed.
Who is a candidate?
OIT is typically considered for:
- Children and adults with confirmed peanut allergy
- Families motivated to commit to a multi-year process with daily dosing
- Patients with well-controlled asthma (uncontrolled asthma is a contraindication during dosing)
- Families with the schedule flexibility to attend regular build-up visits
It is not appropriate for everyone, and for some families the existing avoidance-plus-EpiPen approach remains the right choice.
The risks worth understanding
- Reactions during dosing are expected. Most are mild (oral itching, abdominal discomfort) but a meaningful minority of patients require epinephrine at some point during their course.
- Eosinophilic esophagitis develops in a small subset of OIT patients. Monitoring for symptoms (dysphagia, food impaction) is part of the protocol.
- Adherence burden. Daily dosing for an indefinite period is not trivial. Missing doses can result in loss of desensitisation.
What to expect from a careful programme
OIT is best delivered in an environment with structured protocols, in-clinic observation during dose escalations, ready access to emergency medication, and clear lines of communication with the family between visits. The decision to start is a shared one, with realistic expectations on both sides about effort, risk, and likely outcomes.
Our Allergy Rapid Access Clinic evaluates candidates for OIT and provides pre-OIT counselling. Most referred patients are seen within the same week.