Can you develop an anaphylactic allergy to peanuts in adulthood?

Development of Anaphylactic Peanut Allergy in Adulthood

Yes, it is possible to develop an anaphylactic allergy to peanuts in adulthood, with approximately 17% of adults with peanut allergy reporting onset of their condition after age 18. 1

Epidemiology of Adult-Onset Peanut Allergy

Adult-onset peanut allergy represents a significant portion of the overall peanut allergy burden:

• Approximately 4.6 million US adults have peanut allergy, with over 800,000 developing it after age 18 1
• The prevalence of current self-reported peanut allergy is 2.9% among US adults, with 1.8% having convincing symptoms consistent with IgE-mediated reactions 1
• Peanut allergy is a major cause of food-induced anaphylaxis, with increasing prevalence worldwide 2

Clinical Characteristics of Adult-Onset vs. Childhood-Onset Peanut Allergy

There are important differences between adult-onset and childhood-onset peanut allergy:

• Adults with childhood-onset peanut allergy are more likely to have physician-diagnosed peanut allergy (75.4%) compared to those with adult-onset peanut allergy (58.9%) 1
• Despite similar rates of emergency department visits (approximately 1 in 5 adults with peanut allergy), adults with childhood-onset peanut allergy are:
  • More likely to have a current epinephrine prescription (56% vs. 44%) 1
  • More likely to use an epinephrine autoinjector (48% vs. 35%) 1

Risk Factors for Developing Peanut Allergy

Several factors may increase the risk of developing peanut allergy at any age:

• Presence of other atopic conditions, such as atopic dermatitis (eczema) 3
• Asthma is a significant risk factor for severe allergic reactions to foods 3
• Skin barrier dysfunction 3
• The timing and route of exposure to peanuts may influence sensitization 3

Clinical Presentation of Peanut Allergy

Peanut allergy can present with a range of symptoms:

• Anaphylactic reactions (severe, potentially life-threatening)
• Non-anaphylactic presentations including:
  • Gastrointestinal symptoms
  • Mild skin reactions
  • Oral allergy syndrome
  • Respiratory symptoms that are not severe 3

Management of Peanut Allergy

For individuals who develop peanut allergy in adulthood, management includes:

1. Complete elimination of peanuts and peanut products from the diet 3
2. Education on hidden sources of peanut allergens 3
3. Emergency action plan for IgE-mediated reactions 3
4. Prescription of epinephrine auto-injector for treatment of anaphylaxis 4
   • 0.3 mg epinephrine autoinjector, IM (anterior-lateral thigh) for adults >25 kg
   • Epinephrine doses may need to be repeated every 5-15 minutes

Diagnosis of Adult-Onset Peanut Allergy

Proper diagnosis is essential and may include:

• Food-specific IgE testing for peanut 3
• Skin prick testing for immediate hypersensitivity reactions 3
• The gold standard: elimination followed by controlled challenge under medical supervision 3

Important Considerations

• Unlike many other food allergies, peanut allergy usually persists through adulthood 2
• Conventional subcutaneous-injection allergen immunotherapy using crude peanut extract is not recommended due to risk of severe side effects 2, 5
• Distinguishing between true peanut allergy and peanut intolerance is crucial, as they involve different mechanisms 3
• Cross-reactivity with tree nuts (like cashews) may occur but is unpredictable 6

Emerging Treatments

Research is ongoing for potential treatments including:

• T-cell-epitope peptide vaccines
• Hypoallergenic mutant vaccines
• Alternative routes of administration such as sublingual immunotherapy 2

Adult-onset peanut allergy is a serious condition that requires prompt diagnosis, appropriate management, and emergency preparedness to prevent potentially life-threatening anaphylactic reactions.