Allergies
- The body’s reaction to something that is normally harmless (Patient Education – Allergies); exaggerated immune response to benign antigens – it is the immune response, not the antigen, that is harmful to the host (Chap 65: Hypersensitivity (Allergies) In: Review of medical microbiology and immunology); hypersensitivity reactions occur due to external (non-self) antigens; auto-immune responses occur due to internal (self) antigens
- Hypersensitivity reactions are antigen-specific
- First contact with antigen sensitizes/primes the immune system
- Subsequent antigen exposures will result in clinical manifestations that may increase with time (Review of Medical Microbiology…); once body sensitive to substance, it will react every time – can be mild or life-threatening (Patient Ed)
- Can have immediate reactions (anaphylactic, IgE-mediated: antigen causes IgE antibody to bind to mast cells and basophils which causes mediator release (e.g., histamine) – symptoms occur in minutes to hours.
- Takeaways
- Decongestants are the most common nonprescription agents for treatment for congestion related to colds and allergic rhinitis, but caution is advised with their use in patients with hypertension, diabetes, and other chronic diseases.
- The treatment approach to allergic rhinitis is sequential and consists of allergen avoidance, pharmacotherapy, and allergen immunotherapy.
- Medical referral is appropriate for patients with symptoms suggestive of nonallergic rhinitis, otitis media, sinusitis, or lower respiratory tract problems such as pneumonia, asthma, or bronchitis, and for those patients who fail to respond to nonprescription medications.
- Antihistamines are commonly used to control allergic rhinitis symptoms. Nonsedating (second-generation) antihistamines are preferred over sedating (first-generation) antihistamines on the basis of safety and efficacy data.
