Can a Patient Get Allergy Shots the Day After a Flu Shot?
Yes, a patient can safely receive allergy immunotherapy (allergy shots) the day after receiving an influenza vaccine, as there are no contraindications or required waiting periods between these two types of injections.
Evidence-Based Rationale
Concurrent Vaccine Administration Guidelines
The Advisory Committee on Immunization Practices (ACIP) provides clear guidance on vaccine timing that directly applies to this scenario:
Inactivated vaccines do not interfere with the immune response to other inactivated vaccines or to live vaccines, and inactivated vaccines can be administered simultaneously or at any interval before or after other vaccines 1.
Influenza vaccines (inactivated formulations) may be administered simultaneously with other vaccines, and there is no required waiting period between inactivated vaccines 1.
The only timing restriction for influenza vaccines involves live attenuated vaccines, where at least 4 weeks should pass after a live vaccine before administering another live vaccine 1. This does not apply to allergy immunotherapy, which is not a live vaccine.
Allergy Immunotherapy Considerations
Allergy shots can proceed on their normal schedule without modification after flu vaccination:
There is no evidence or guideline recommendation suggesting that recent influenza vaccination increases the risk of systemic reactions to allergen immunotherapy 2, 3.
The standard safety protocols for allergy immunotherapy remain unchanged regardless of recent influenza vaccination, including the typical 30-60 minute observation period after injection 3.
Patients should not have moderate-to-severe acute illness at the time of either injection, but mild upper respiratory symptoms or allergic rhinitis do not contraindicate either procedure 4, 1.
Clinical Algorithm for Decision-Making
Proceed with allergy shots the day after flu vaccination if:
The patient did not experience an immediate allergic reaction (hives, angioedema, respiratory distress, anaphylaxis) to the flu vaccine 5.
The patient does not have moderate-to-severe acute illness with fever 1.
Normal injection site soreness or mild systemic symptoms (low-grade fever, fatigue, myalgia) are present, as these are expected non-allergic reactions that do not contraindicate allergy immunotherapy 5, 1.
Defer allergy shots if:
The patient developed true allergic symptoms (hives, lip/tongue swelling, respiratory distress) after the flu vaccine, requiring allergist evaluation before proceeding 5.
The patient has developed moderate-to-severe febrile illness, regardless of whether it is related to the flu vaccine 1.
Common Pitfalls to Avoid
Do not confuse normal post-vaccination reactions with contraindications to allergy shots:
Injection site soreness lasting up to 2 days affects 10-64% of flu vaccine recipients and is not a contraindication to allergy immunotherapy 5, 1.
Systemic symptoms (fever, malaise, myalgia) beginning 6-12 hours after flu vaccination and lasting 1-2 days are normal inflammatory responses, not allergic reactions 5, 1.
These non-allergic reactions do not increase the risk of systemic reactions to allergen immunotherapy 5.
Do not delay allergy immunotherapy unnecessarily:
There is no immunologic rationale for spacing these two different types of injections apart 1.
Delaying allergy shots disrupts the build-up or maintenance schedule without providing any safety benefit.