Hypersensitivity, Anaphylaxis, and Infusion Reactions

Hypersensitivity, Anaphylaxis, and Infusion Reactions

Oncology patients receive many agents that trigger hypersensitivity or infusion reactions: monoclonal antibodies (rituximab, cetuximab), taxanes (paclitaxel, docetaxel), platinums (carboplatin, oxaliplatin), asparaginase, immunotherapy, blood products, and supportive drugs. Reactions may be IgE-mediated, cytokine-mediated, complement-mediated, or driven by excipients such as Cremophor (in solvent-based paclitaxel). The bedside response is the same regardless of mechanism: recognize, stop the exposure, assess severity, call for help, support airway and circulation, and give ordered rescue medications.

Timing and Drug-Specific Patterns

A key OCN distinction is timing. Reactions in the first few minutes of a first dose are typical of taxanes and monoclonal antibodies and are usually cytokine/infusion reactions, often manageable with rate reduction and premedication. True IgE-mediated allergy to platinum agents classically emerges after multiple prior uneventful cycles (often after 6 or more), because sensitization takes repeated exposure.

Immediate Nursing Actions and Epinephrine

For any concerning reaction, stop the infusion first. Maintain IV access with compatible fluid, assess airway, breathing, circulation, vital signs, oxygen saturation, lung sounds, skin, and mental status. Call the provider, infusion-reaction team, or rapid response based on severity, position the patient supine with legs elevated if hypotensive, apply oxygen, and stay at the bedside.

Anaphylaxis is a clinical diagnosis - suspect it with acute onset of skin or mucosal involvement plus either respiratory compromise or hypotension, or two or more organ systems after a likely allergen. The single most important drug is intramuscular epinephrine: the adult dose is 0.3 to 0.5 mg of the 1 mg/mL (1:1000) concentration into the anterolateral thigh (vastus lateralis), repeatable every 5 to 15 minutes. Antihistamines and corticosteroids are adjuncts only and must never delay epinephrine. Know where emergency medications and airway equipment are before you start any high-risk infusion.

Premedication and Prevention

Before administration, verify allergies, prior reactions, ordered premedications, baseline vital signs, and emergency readiness. Paclitaxel and many monoclonal antibodies require premedication with a corticosteroid (e.g., dexamethasone), an H1 blocker (diphenhydramine), and an H2 blocker (famotidine). Monitor most closely during the first dose, step-up dosing, rate increases, and any rechallenge. For blood products, follow the transfusion-reaction policy and stop the transfusion for any suspected serious reaction.

Rechallenge, Documentation, and Education

Do not restart an infusion after a significant reaction unless the provider and protocol direct it. Rechallenge and desensitization decisions weigh severity, symptom resolution, how essential the drug is, premedication, and infusion rate. Document the drug, dose, lot if required, premedications, start time, exact time symptoms began, full assessment, vital-sign nadir, every intervention, the patient's response, notifications, and education. This detail is load-bearing: the next team must know whether the event was mild flushing, cytokine-driven rigors, or true anaphylaxis.

Teach patients to report symptoms the instant they occur rather than hoping they pass - many patients stay quiet because they do not want to interrupt treatment. Be explicit: itching, chest tightness, throat or tongue symptoms, dizziness, shortness of breath, severe back pain, or swelling must be reported at once. After discharge, instruct patients to seek emergency care for delayed swelling, trouble breathing, recurrent hives, fainting, or worsening chest symptoms, which can signal a biphasic reaction hours later.

Differentiating Reaction Types

Cytokine-mediated infusion reactions feature fever, chills, rigors, hypotension, and hypoxia without classic urticaria. Allergic or anaphylactic reactions involve airway edema, wheezing, urticaria, GI cramping, and shock. The nurse does not need to name the mechanism before acting - severity and patient stability drive the response. Baseline assessment helps, because chronic dyspnea, anxiety, pain, or flushing may already be present before the infusion starts.

Monitoring, Transfusion Reactions, and Handoff

Monitor most intensively during the first 15 minutes of any high-risk infusion, since that is when most cytokine-driven reactions begin; many protocols specify a slow initial rate that is escalated only if tolerated.

For blood products, distinguish reaction types because management differs: an acute hemolytic reaction (fever, flank or back pain, dark urine, hypotension during the first minutes) is life-threatening and requires stopping the transfusion, keeping the line open with saline, and sending the unit and blood samples back; a febrile non-hemolytic reaction (isolated fever and chills) is less dangerous but still warrants stopping and assessing; and a mild allergic reaction (urticaria only) may be managed per policy with antihistamines. When in doubt, stop the transfusion - you can always restart, but you cannot undo a missed hemolytic reaction.

During handoff after any hypersensitivity event, include the exact sequence: premedications given, the infusion rate, the time symptoms began relative to the start, whether the drug was stopped, the vital-sign nadir (lowest blood pressure and oxygen saturation), respiratory findings, every medication administered including epinephrine doses and times, and whether symptoms fully resolved or recurred. This precise record is what guides future desensitization, rechallenge, premedication, or permanent-avoidance decisions, and it protects the patient across the entire treatment course.