Xolair Side Effects and Monitoring
Most Critical Side Effect: Anaphylaxis
The most serious side effect of Xolair is anaphylaxis, occurring in 0.09-0.2% of patients, with 61% of reactions happening within the first 2 hours after one of the first three doses. 1, 2
Anaphylaxis Risk Timeline
- Within 30 minutes: 16 documented anaphylactic reactions 2
- 30-60 minutes: 7 reactions 2
- 1-2 hours: 5 reactions 2
- 2-12 hours: 5 delayed reactions including tongue swelling, lingual angioedema, increased asthma symptoms with urticaria, and throat closing sensation 2
- Beyond 12 hours: 3 reactions documented up to 4 days after administration 2
Mandatory Monitoring Protocol
Patients must be observed for 2 hours after each of the first 3 injections, then 30 minutes after subsequent injections. 3, 1, 2 This captures 75% of anaphylactic reactions. 2
Before each injection, assess:
- Current health status and recent health changes 3
- Vital signs 3
- Lung function (peak expiratory flow or FEV₁) 3
Required Patient Education and Preparation
All patients must:
- Receive informed consent discussion about anaphylaxis risk 3, 1
- Be prescribed an epinephrine autoinjector before starting therapy 3, 1
- Receive training on proper epinephrine autoinjector use 3
- Carry the epinephrine autoinjector for 24 hours following each injection 2
- Understand that reactions can occur up to 4 days after administration 2
Common Side Effects
In Adults and Adolescents ≥12 Years with Asthma:
- Joint pain (especially arms and legs) 4
- Dizziness 4
- Fatigue 4
- Itching and skin rash 4
- Bone fractures 4
- Ear pain or discomfort 4
- Injection site reactions 5, 6
- Viral infections 5, 6
- Upper respiratory tract infection 5, 6
- Sinusitis 5, 6
- Headache 5, 6
- Pharyngitis 5, 6
In Children 6 to <12 Years with Asthma:
- Swelling of nose, throat, or sinuses 4
- Headache 4
- Fever 4
- Throat infection 4
- Ear infection 4
- Abdominal pain 4
- Stomach infection 4
- Nosebleeds 4
In Adults with Chronic Rhinosinusitis with Nasal Polyps:
In Chronic Spontaneous Urticaria:
- Nausea 4
- Headaches 4
- Swelling of nose, throat, or sinuses 4
- Cough 4
- Joint pain 4
- Upper respiratory tract infection 4
In Food Allergy:
Important note: The incidence of adverse events with omalizumab was similar to placebo in clinical trials. 5, 6, 7
Serious but Rare Side Effects
Cancer Risk
Cases of cancer have been observed in patients receiving Xolair, though causality is not established. 4
Blood Vessel Inflammation (Vasculitis)
- Occurs rarely, usually in asthma patients also taking oral steroids that are being stopped or dose-reduced 4
- Causality with Xolair is uncertain 4
Immediate symptoms requiring medical attention:
Serum Sickness-Like Reaction
- Fever, muscle aches, and rash occurring 1-5 days after injection 4
Parasitic Infections
Patients at high risk for parasitic (worm) infections may develop these after receiving Xolair. 4 Stool testing can identify parasitic infections. 4
Cardiovascular Events
Some patients have experienced chest pain, heart attack, blood clots in lungs or legs, or transient stroke-like symptoms (weakness on one side, slurred speech, altered vision), though causality with Xolair is not established. 4
Critical Pitfalls to Avoid
- Never use Xolair for emergency treatment of allergic reactions, anaphylaxis, hives, or sudden breathing problems. 4
- Do not reduce or stop other asthma, chronic rhinosinusitis with nasal polyps, hives, food allergy medications, or allergen immunotherapy without provider guidance. 4
- Do not assume patients are safe after the observation period—educate them about delayed reactions up to 4 days later. 2
- Do not skip the 2-hour observation for the first 3 doses—this is when most severe reactions occur. 1, 2