For most of the history of peanut and tree nut allergies, the answer to treatment was ‘’avoid nuts and carry an adrenaline pen’’. That answer has been changing. Oral immunotherapy (OIT), which is the process of gradually introducing tiny amounts of an allergen under medical supervision to build tolerance, has moved from experimental curiosity to licensed treatment in a few years. However in January 2026, the manufacturer of the only NHS-approved peanut OIT product called Palforzia, announced it was discontinuing production worldwide. Not because it didn't work but because of commercial strategy, which is common for pharmaceutical companies. The nut allergy community is still processing what that means. Here we explore what OIT is, what the evidence shows, and why the discontinuation of one product is not the end of the story.
How does oral immunotherapy work
The principle behind OIT is quite scary sounding from the perspective of someone who has spent their life avoiding something that could kill them in small amounts. The treatment involves ingesting the allergen; in the case of peanut OIT, a measured dose of peanut powder daily. This starts at an imperceptibly small amount and increases gradually over months under careful clinical supervision. The goal is to change the immune system's response. Specifically, to reduce the sensitivity of the mast cells and basophils that drive allergic reactions, and to move the immune response away from the IgE-mediated pathway that causes anaphylaxis toward one that is better regulated. The full mechanism is not fully understood as with most complex immunology. However, the outcome in clinical terms is that after successful 'desensitisation', a person allergic to peanuts can tolerate accidental exposure to a quantity of peanuts that would previously have triggered a severe reaction. This is not a cure, and daily maintenance doses are required to sustain the effect, but it reduces the risks of accidentally ingesting peanuts. Even when going through OIT, general avoidance of the allergen is still the basic advice.
The PALISADE trial
The PALISADE clinical trial demonstrated that 67% of treated participants could tolerate at least 600mg of peanut protein, roughly equivalent to two peanuts, compared to just 4% of those on placebo [1].
Palforzia, the licensed peanut OIT product, achieved a 60–70% rate of successful desensitisation for children who reacted to 100mg or less of peanut protein which is about half a peanut [2].
60-70% successful desensitisation means the majority of children who complete the treatment can tolerate accidental exposure that would have previously caused anaphylaxis. What it doesn't mean is that they can eat peanuts freely or that the allergy has gone. The treatment is maintained by taking it daily. If patients stop taking it the tolerance gradually fades. For some families with regular histories of reactions and anaphylaxis this is transformative. For others, trading one daily management task for another while being exposed to the risk that comes with the treatment itself, doesn't feel like the right option. OIT changes the risk profile of the allergy rather than resolving it, and whether that change feels worth the process is up to the individual and their family.
What OIT involves and why it isn't always straightforward
OIT sometimes results in serious adverse events including systemic reactions and anaphylaxis during the treatment process itself. The treatment requires multiple clinical visits for dose escalation, careful monitoring, and management of co-conditions including asthma. It involves deliberately introducing an allergen into someone who is allergic to it, and so reactions are common when increasing the amount of peanut. These might be mild reactions with symptoms like oral itching and stomach discomfort, but more serious reactions including anaphylaxis do occur, which is why the treatment requires specialist clinical supervision and access to adrenaline throughout. Poorly controlled asthma significantly increases the risk, which is one of the reasons eligibility assessment is important. There are also cofactors like exercise, illness, and sleep deprivation, that lower the threshold for reactions during treatment, requiring patients to avoid certain activities around dosing times. This is not a decision to make casually, and it is absolutely not something to attempt without specialist involvement.
Palforzia and why it's being discontinued
Palforzia was the approved licensed oral immunotherapy for peanut allergy, available for children aged 4–17. Its manufacturer, Stallergenes Greer, announced in January 2026 that it would cease production worldwide by July 2026, stating explicitly that the decision was not related to the safety, quality, or effectiveness of the treatment.
The product worked and the clinical evidence supporting it was robust. What it struggled with was market adoption, in part due to the intensive clinical requirements of its treatment pathway, NHS capacity constraints, and a complex corporate journey from its original developer through Nestlé to Stallergenes Greer. The demand for peanut OIT was consistently larger than NHS capacity to deliver it. Ultimately the commercial return didn't justify continued production. For families who were on waiting lists with the hope of a treatment that represented more freedom in everyday life, this is a genuine setback. But this doesn’t impact the science of OIT - the treatment worked, and the knowledge generated through Palforzia's clinical programme informs what comes next.
What this means for tree nut allergy
Almost everything discussed here applies specifically to peanut allergy. OIT for tree nut allergies remains largely in research settings. Clinical trials for tree nut SLIT are ongoing, and there is interest in whether desensitisation to one tree nut can create some cross-tolerance to others given shared protein structures. But as of now, there is no licensed tree nut OIT product, and real-food protocols for tree nuts are less developed than for peanuts. For people managing tree nut allergy specifically, the honest answer is that the treatment landscape is less advanced. For now, avoidance and emergency preparedness remain the foundation.
Real-food OIT and other treatment options
Following Palforzia, significant progress is being made in real-food immunotherapy with the aim of making OIT safer, more effective and more widely available through the NHS. Real-food OIT, using measured doses of commercially available peanut products rather than pharmaceutical-grade powder, has long been used by specialist allergists and the evidence base for it is solid. It is less standardised than Palforzia was, which creates variability between clinicians and settings, but it does not require a licensed product to deliver. Several allergy centres in the UK already operate real-food OIT programmes, and these are likely to expand as the Palforzia pathway closes.
Sublingual immunotherapy, skin patches, and a new generation of anti-IgE biologics are other treatment options being worked on. Sublingual immunotherapy (SLT) for peanut allergy has shown safety advantages over OIT in several studies, causing fewer side effects while maintaining clinical effectiveness. This involves placing small, liquid doses of allergens like peanut or hazelnut under the tongue to build tolerance, offering a lower-dose alternative to oral immunotherapy. Biologics include a drug named omalizumab, which is already licensed for food allergy in the US and in trials in the UK. Research is not retreating and Palforzia's commercial failure has created pressure to develop more affordable alternatives faster.
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