How to Perform Allergen Immunotherapy
For patients with allergic rhinitis inadequately controlled by medications, initiate either subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT) after confirming IgE-mediated allergy through skin or blood testing, with treatment selection based on patient preference, convenience needs, and contraindications. 1
Patient Selection and Pre-Treatment Requirements
Who Should Receive Immunotherapy
- Patients ≥5 years old with allergic rhinitis confirmed by positive allergy testing (skin prick or specific IgE) 1
- Inadequate symptom control despite pharmacotherapy with or without environmental controls 2, 3
- Patients experiencing medication side effects or wishing to reduce long-term medication use 4
Absolute Contraindications - DO NOT Initiate 1
- Pregnancy (maintenance may continue if already established)
- Uncontrolled asthma (must be controlled before each injection)
- Inability to tolerate injectable epinephrine
Relative Contraindications - Exercise Caution 1
- Beta-blocker use (both selective and non-selective)
- History of anaphylaxis
- Systemic immunosuppression
- Eosinophilic esophagitis (for SLIT only)
Mandatory Asthma Assessment
Evaluate all patients for asthma before initiating immunotherapy and reassess for uncontrolled asthma before each subsequent dose. 1 This is critical as uncontrolled asthma significantly increases anaphylaxis risk.
Subcutaneous Immunotherapy (SCIT) Protocol
Starting Dose Selection 4, 5
- Standard starting dose: 1:10,000 or 1:1,000 dilution of maintenance concentrate
- Highly sensitive patients: Use more dilute concentrations (1:100,000) based on history and skin test reactivity
- Target maintenance dose: 1,000-4,000 AU/BAU for standardized extracts, or 5-20 mcg major allergen for inhalant allergens
Build-Up Phase 4, 5
- Frequency: 1-2 injections per week (conventional schedule)
- Duration to maintenance: 4-6 months typically
- Accelerated options: Cluster (multiple injections per visit) or rush protocols available but carry higher systemic reaction risk
- Injections may be given as frequently as daily if needed, though weekly is standard
Maintenance Phase 1
- Continue for minimum 3 years for symptomatic control
- Extend duration based on patient response
- Typical maintenance interval: every 2-4 weeks
Critical Safety Requirements 4, 5
- Administer only in settings equipped for anaphylaxis management
- Observe patients for 30 minutes post-injection (when most systemic reactions occur)
- Have epinephrine, oxygen, and resuscitation equipment immediately available
- Administer epinephrine intramuscularly in the thigh for anaphylaxis (not subcutaneously in arm)
Dose Adjustments 4
- After systemic reaction: Reduce to previously tolerated dose or lower
- During high allergen exposure seasons: Consider not increasing or even reducing dose in highly sensitive patients
- After missed doses: Follow package insert guidelines for dose reduction based on interval
Sublingual Immunotherapy (SLIT) Protocol
Dosing 6, 7
- No up-dosing required - can start directly at maintenance dose 6
- Recommended dose: approximately 5 mcg major allergen daily 6
- Administration: Place drops/tablet under tongue, hold 2-3 minutes, then swallow 8
Treatment Schedules 6, 1
- Seasonal allergic rhinitis: Pre- and co-seasonal therapy recommended 1
- Begin 8 weeks before anticipated pollen season for optimal efficacy 6
- Continue through pollen season
- Perennial allergic rhinitis: Continuous year-round administration
Duration 1, 7
- Minimum 3 years for sustained benefit
- Effects persist after discontinuation when adequate duration achieved
Safety Profile 9, 7
- Most adverse effects are local oral reactions (oral itching, throat irritation)
- Systemic reactions rare; no reported fatalities 7
- Can be self-administered at home after first dose observation
- First dose should be given under medical supervision
Allergen Selection 1
Limit treatment to only clinically relevant allergens that correlate with patient history and are confirmed by testing. 1
For Polysensitized Patients 1
- Treat with a limited number of allergens (not all positive tests)
- Select based on:
- Clinical symptom correlation
- Exposure history
- Allergen potency and cross-reactivity
- Avoid mixing incompatible allergens that may degrade each other
Managing Reactions
Local Reactions 1
- Continue escalation or maintenance dosing - local reactions do not predict systemic reactions 1
- Occurred after 1.6% of injections in one study 9
- Manage symptomatically
Systemic Reactions 9, 4
- Incidence: 1.29% of injections in published data 9
- Most are late reactions (>30 minutes): dyspnea, rhinorrhea, urticaria, fatigue
- Higher risk during up-dosing phase and with grass pollen allergens 9
- Treatment: Immediate intramuscular epinephrine in thigh, supportive care
Patient Education Requirements 1
Before initiating, discuss:
- Differences between SCIT and SLIT: risks, benefits, convenience, costs
- Expected onset of efficacy (typically 6 months) 8
- Duration of treatment commitment (minimum 3 years)
- Risk of anaphylaxis and importance of adherence
- Preventive benefits: May prevent new allergen sensitizations, reduce asthma development risk, and provide continued benefit after discontinuation 1
Monitoring During Treatment
Do NOT Routinely Repeat Allergy Testing 1
- Repeat testing only if:
- Change in environmental exposures
- Loss of symptom control
- Testing does not assess immunotherapy efficacy
Common Pitfalls to Avoid
- Mixing allergens incorrectly - avoid "off-the-board" mixing from multiple vials at time of injection; use pre-mixed patient-specific vials 4
- Inadequate observation time - 30-minute post-injection wait is mandatory 4
- Giving injections during uncontrolled asthma - always assess asthma control first 1
- Premature discontinuation - minimum 3-year duration needed for sustained benefit 1, 7
- Treating all positive skin tests - select only clinically relevant allergens 1