What the label lists and what reports show
Efgartigimod alfa and hyaluronidase side effects
Efgartigimod alfa and hyaluronidase's FDA label: “The most common adverse reactions (≥ 10%) in patients with gMG treated with efgartigimod alfa-fcab were respiratory tract infections, headache, and urinary tract infection.” FAERS holds 427 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (57 reports).
- No generic listed
Check it at the source: the efgartigimod alfa and hyaluronidase FDA label on DailyMed (effective July 15, 2026); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of VYVGART HYTRULO?VYVGART HYTRULO can cause side effects which can be serious, including: Infection. VYVGART HYTRULO may increase the risk of infection. If you have an active infection, your healthcare provider should delay your treatment with VYVGART HYTRULO until your infection is gone. Tell your healthcare provider right away if you get any of the following signs and symptoms of an infection: fever chills frequent and painful urination cough pain and blockage of nasal passages wheezing shortness of breath sore throat excess phlegm nasal discharge Allergic reactions (hypersensitivity reactions). VYVGART HYTRULO can cause allergic reactions that can be severe. These reactions can happen during, shortly after, or weeks after your VYVGART HYTRULO injection. […]
Source: FDA drug label, argenx US, effective July 15, 2026 (SPL set 7104d9e5-9910-47f5-9a93-741ac50f43b6), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (≥ 10%) in patients with gMG treated with efgartigimod alfa-fcab were respiratory tract infections, headache, and urinary tract infection.
Table 1: Adverse Reactions in at least 5% of Patients with gMG Treated with Efgartigimod Alfa-fcab Intravenously (EFG IV) and More Frequently than in Placebo-Treated Patients in Study 1 (Safety Population)
| Adverse reaction | EFG IV (N=84) % | Placebo (N=83) % |
|---|---|---|
| Respiratory tract infection | 33 | 29 |
| Headache Headache includes migraine and procedural headache. | 32 | 29 |
| Urinary tract infection | 10 | 5 |
| Paraesthesia Paresthesia includes oral hypoesthesia, hypoesthesia, and hyperesthesia. | 7 | 5 |
| Myalgia | 6 | 1 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are described elsewhere in the labeling: Infections [see Warnings and Precautions (5.1) ] Hypersensitivity Reactions [see Warnings and Precautions (5.2) ] Infusion/Injection-Related Reactions [see Warnings and Precautions (5.3) ] The most common adverse reactions (≥ 10%) in patients with gMG treated with efgartigimod alfa-fcab were respiratory tract infections, headache, and urinary tract infection. Injection site reactions were common (≥ 15%) in patients with gMG and CIDP who were treated with VYVGART HYTRULO ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact argenx at 1-833-argx411 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. …
Source: FDA drug label, argenx US, effective July 15, 2026 (SPL set 7104d9e5-9910-47f5-9a93-741ac50f43b6), via openFDA; the full label on DailyMed
What do FAERS reports show?
427 reports list efgartigimod alfa and hyaluronidase among the medicines taken, each a report of something that happened, not proof the medicine caused it; 19 are coded as a death and 153 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 5 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Efgartigimod alfa and hyaluronidase: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions