Effects of Inhaled Epinephrine on Systemic Allergic Reactions During Allergy Testing Immunotherapy or Oral Challenges

Inclusion Criteria: 1. Males or females, aged ≥ 18 years with known or suspected metabisulfite sensitivity who can also have a clinical history of immunoglobulin E (IgE)-mediated allergy, including a documented sensitivity to allergens (i.e., positive skin prick test, or positive in vitro serum IgE). 2. Have undergone either a) allergy testing for suspected sensitivity/allergy, b) oral challenge (food and/or drug), c) oral immunotherapy (OIT) to treat existing allergies or d) subcutaneous immunotherapy (SCIT) following a prior allergic reaction AND experiences a systemic allergic reaction (SAR) rated as Grade ≥2, following allergy testing, SCIT, oral challenge (food and/or drug), or OIT, and deemed eligible for enrollment by the Principal Investigator. 3. For females of child-bearing potential, not pregnant or lactating, willing to use a highly effective method of birth control between Screening and End-of-Study Visits. Exclusion Criteria: 1. Known reaction or sensitivity to epinephrine or any of the ingredients of inhaled epinephrine. 2. Known history or presence of clinically relevant cardiovascular, respiratory, hepatic, renal, hematologic, gastrointestinal, endocrine, immunologic, dermatologic, neurological, psychological or other disease/condition that could confound the results of the study or place the subject at undue or additional risk per the judgment of the Investigator. 3. Uncontrolled asthma or chronic obstructive pulmonary disease (COPD). 4. Recent life-threatening asthma within the last 6 months which required admission to hospital prior to study start. 5. Use of any tobacco or of any inhaled products, including vaping and water pipes (Hookahs) within 12 months prior to screening and/or a 10 pack per year history of use. 6. Use of antihistamines within 5 days and/or bronchodilators within 24 hours of pre-challenge visit. 7. Surgical procedures within 90 days of screening that could result in confounding of results or additional risk to the subject, per the judgment of the Investigator. 8. Abnormal vital signs at screening (i.e., systolic blood pressure: \< 90 or \>140 mmHg, diastolic blood pressure: \< 40 or \> 90 mmHg or, Heart rate: \< 45 or \> 100 bpm), respiration rate \< 8 or \> 20 resp./min. 9. Females who are pregnant, plan to become pregnant or lactating. 10. Participation in another clinical study involving an investigational drug within 30 days prior to screening, an investigational biologic within 60 days prior to screening, or current/planned participation in another interventional study during this study. 11. Previous treatment in this study. 12. Any other reason that, in the opinion of the Investigator, is likely to unfavourably alter subject risk-benefit, confound results, or make it difficult for the subject to fully comply with study requirements.