What the label lists and what reports show
Satralizumab side effects
Satralizumab's FDA label: “The most common adverse reactions (incidence at least 15%) are nasopharyngitis, headache, upper respiratory tract infection, gastritis, rash, arthralgia, extremity pain, fatigue, and nausea.” FAERS holds 1,684 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 urinary tract infection (136 reports).
- No generic listed
Check it at the source: the satralizumab FDA label on DailyMed (effective June 22, 2026, Genentech, Inc.); 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 ENSPRYNG?ENSPRYNG may cause serious side effects, including: See " What is the most important information I should know about ENSPRYNG? " Serious allergic reactions. Serious allergic reactions that may be life-threatening have happened with other medicines like ENSPRYNG. Tell your healthcare provider before taking your next dose if you had hives, rash, or flushing after your injection. […]
Source: FDA drug label, Genentech, Inc., effective June 22, 2026 (SPL set 64c156a4-9bad-4d45-a294-0733c141f47b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (incidence at least 15%) are nasopharyngitis, headache, upper respiratory tract infection, gastritis, rash, arthralgia, extremity pain, fatigue, and nausea.
Table 3 Adverse Reactions Occurring in 4 or More Patients Treated with ENSPRYNG and Greater Incidence than Placebo in Study 1
| Adverse Reaction | ENSPRYNG (N = 41) % | PLACEBO (N = 23) % |
|---|---|---|
| Rash | 17 | 0 |
| Arthralgia | 17 | 0 |
| Pain in extremity | 15 | 9 |
| Fatigue | 15 | 4 |
| Nausea | 15 | 9 |
| Nasopharyngitis | 12 | 4 |
| Pruritus | 10 | 0 |
| Depression | 10 | 0 |
| Cellulitis | 10 | 0 |
| Neutropenia | 10 | 4 |
| Blood creatine phosphokinase increased | 10 | 4 |
| Fall | 10 | 4 |
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) ] Elevated Liver Enzymes [see Warnings and Precautions (5.2) ] Decreased Neutrophil Counts [see Warnings and Precautions (5.3) ] Hypersensitivity Reactions [see Warnings and Precautions (5.4) ] The most common adverse reactions (incidence at least 15%) are nasopharyngitis, headache, upper respiratory tract infection, gastritis, rash, arthralgia, extremity pain, fatigue, and nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Genentech at 1-888-835-2555 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in clinical practice. The safety of ENSPRYNG was evaluated in two randomized, placebo-controlled clinical trials [Study 1 evaluated ENSPRYNG without concurrent immunosuppressive therapy (IST) and Study 2 evaluated ENSPRYNG with concurrent IST], which included 41 anti-AQP4 seropositive patients treated with ENSPRYNG in Study 1 and 26 anti-AQP4 seropositive patients treated with ENSPRYNG in Study 2 [see Clinical Studies (14) ]. …
Source: FDA drug label, Genentech, Inc., effective June 22, 2026 (SPL set 64c156a4-9bad-4d45-a294-0733c141f47b), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,684 reports list satralizumab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 99 are coded as a death and 649 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 21 reactions below, 7 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.
Reports received each year
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?
- Satralizumab: 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