Omalizumab Side Effects in Patients With Chronic Urticaria Highlighted

Although long-term use of omalizumab for patients with chronic urticaria is known to be safe and well-tolerated, new findings suggest that the most common side effects seen among 32.9% of those treated with omalizumab include headaches, fatigue, and flu-like symptoms.1

These findings were the result of an analysis looking at omalizumab’s side effects in real-world settings. This study on patients with chronic urticaria was authored by Reineke Soegiharto, from the Department of Dermatology/Allergology at the University Medical Centre Utrecht in the Netherlands.

Soegiharto and coauthors highlighted that real-world studies are necessary to elucidate omalizumab’s long-term safety profile and, thereby, to improve personalized medicine in an era where newer therapies for chronic urticaria have begun to emerge.2

“To this end, we investigated the spectrum of side effects of omalizumab in [chronic urticaria] patients by assessing the prevalence of reported side effects and identifying determinants for the reporting of side effects in a large, long-term real-world cohort study,” Soegiharto and colleagues wrote.1

In 14 specialized care centers for patients with urticaria, the investigative team conducted their research using a retrospective, international, multicentre cohort analysis design. These had been designated as Urticaria Centres of Reference and Excellence (UCAREs) and were located in 10 countries.

The teams' aim in their analysis was to assess the drug survival and tolerability of omalizumab among those with chronic urticaria. Clinicians would, at each study site, record whether participants experienced any side effects during omalizumab therapy that were considered related to the drug by the treating physician. These effects were documented by the investigators as "yes," "no," or "unknown" in the medical records.

Side effects reported by the clinicians which are deemed to be omalizumab-associated were extracted from medical records, based on descriptions from either physicians or patients themselves. Such adverse events were classified by Soegiharto and colleagues using system organ classes as defined by the Medical Dictionary for Regulatory Activities (MedDRA).

Additional collected data included baseline patient demographic information, disease control/activity scores at both the point of initiation and completion of omalizumab use, and details about the treatment. Disease control was assessed by the investigators utilizing the Urticaria Control Test (UCT), whereas they determined disease activity through the use of the Weekly Urticaria Activity Score (UAS7).

When disease activity scores were missing, the investigative team inferred treatment responses and timing of onset using clinicians’ notes. All centers taking part in the study would, to improve understand the context and practices that might impact side effect reporting, fill out a questionnaire regarding their consultation approaches.

The study ended up with 1859 individuals included as subjects, with 32.9% having reported experiencing side effects while using omalizumab treatment. However, those reporting rates varied considerably across the centers that were evaluated, ranging from 0% - 75.5%. The most commonly reported adverse events were shown to be fatigue among 15.8%, headaches in 11.6%, and flu-like symptoms in 9.3%.

Notably, Soegiharto et al did not observe cases indicative of anaphylaxis. Additionally, they did not find any new and frequently occurring side effects. Hair loss was reported by 2.9% of the study's subjects, and among those with sufficient data, it was noted that 21.1% had their treatment modified as a result of this issue.

The investigative team, in assessing factors linked to side effect experiences, found that those in this group were more likely to be female (78.3% versus 68.6%, P < .001). They also were more likely to have poorer disease control at the point of baseline (mean UCT score: 4.0 versus 6.0, P < .001). The team further highlighted that slower onset of clinical response—defined as UAS7 < 7 or UCT > 11 within 4 weeks—was observed compared to subjects without side effects (42.6% versus 59.5%, P < .001).

The proportion of participants attaining a complete or good response by conclusion of their course of treatment (UAS7 < 7 or UCT > 11) was found by the team to be lower among subjects showing side effects (72.3% versus 84.4%, P < .001).

Despite such conclusions, the investigators reported that only 2.4% of subjects discontinued their medication due to side effects. Among individuals reporting side effects, 5.5% who had not reached sufficient disease control (UAS7 ≥ 7 or UCT 3–11) and 12.8% who attained good or complete response continued their course of omalizumab treatment.

“The reporting of side effects was associated with insufficient omalizumab response, suggesting the increased burden in CU patients and highlighting the importance of achieving complete disease control in CU patients,” they concluded.1 “Although side effects are currently rarely a reason for treatment discontinuation, the availability of new alternative therapies will increase the impact of side effects on treatment decisions.”

References

1. Soegiharto R, Van der Wind E, Alizadeh Aghdam M, et al (2025). Spectrum and Impact of Reported Side Effects of Omalizumab in Patients With Chronic Urticaria: A Long-Term Multicentre Real-World Study. Clin Exp Allergy. https://doi.org/10.1111/cea.70067.

2. M Maurer, TB Casale, SS Saini, et al., “Dupilumab in Patients With Chronic Spontaneous Urticaria (LIBERTY-CSU CUPID): Two Randomized, Double-Blind, Placebo-Controlled, Phase 3 Trials,” Journal of Allergy and Clinical Immunology 154, no. 1 (2024): 184–194.