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What the label lists and what reports show

Rilzabrutinib side effects

Rilzabrutinib's FDA label: “Most common adverse reactions (incidence ≥10%) were diarrhea, nausea, headache, abdominal pain, and COVID-19.” FAERS holds 363 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 platelet count decreased (99 reports).

  • No generic listed

Check it at the source: the rilzabrutinib FDA label on DailyMed (effective August 26, 2025, Genzyme Corporation); 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 WAYRILZ?

WAYRILZ may cause serious side effects, including: Serious infections. WAYRILZ can increase the risk of infections, including serious infections that can lead to death. Your healthcare provider will check you for signs and symptoms of infection during your treatment with WAYRILZ. Tell your healthcare provider right away if you get any signs or symptoms of infection, including fever, chills, or flu-like symptoms. Liver problems including Drug-Induced Liver Injury (DILI). Liver problems, which may be severe, life-threatening, or lead to death have happened in people treated with Bruton’s tyrosine kinase (BTK) inhibitors. Your healthcare provider will do blood tests to check your liver before and as necessary during treatment with WAYRILZ. […]

Source: FDA drug label, Genzyme Corporation, effective August 26, 2025 (SPL set 95ffd367-9b0c-4f75-8487-5d8f3c0a5ad0), via openFDA; the full label on DailyMed

What does the label list?

From the label: adverse reactions

Most common adverse reactions (incidence ≥10%) were diarrhea, nausea, headache, abdominal pain, and COVID-19.

Table 1: Common Adverse Reactions Adverse reactions that occurred in at least 5% of WAYRILZ treated patients and at least 3% higher than placebo-treated patients. in Patients with ITP During Double-Blind Period of the…

ReactionAll Grades %Grade 3 or Higher %All Grades %Grade 3 or Higher %
Diarrhea320100
Nausea20060
Headache18070
Abdominal Pain Grouped term14010
COVID-19140.840
Arthralgia9040
Dizziness8010
Nasopharyngitis7030
Vomiting7010
Dyspepsia5000
Cough5000

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, continued

The following clinically important adverse reactions are described elsewhere in the labeling: Serious Infections [see Warnings and Precautions (5.1) ] Hepatotoxicity, Including Drug-Induced Liver Injury [ see Warnings and Precautions (5.2) ] Most common adverse reactions (incidence ≥10%) were diarrhea, nausea, headache, abdominal pain, and COVID-19. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Genzyme Corporation at 1-800-633-1610 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. The safety of WAYRILZ was evaluated in a randomized, double-blind (DB), placebo-controlled, parallel-group study (LUNA-3), in which 202 adult patients with persistent or chronic ITP received either WAYRILZ (n=133) or placebo (n=69) [see Clinical Studies (14) ]. During the 24-week DB period, the median duration of WAYRILZ exposure was 98 days (range: 22 to 182). The most common adverse reactions (≥10%) were diarrhea, nausea, headache, abdominal pain, and COVID-19. …

Source: FDA drug label, Genzyme Corporation, effective August 26, 2025 (SPL set 95ffd367-9b0c-4f75-8487-5d8f3c0a5ad0), via openFDA; the full label on DailyMed

What do FAERS reports show?

363 reports list rilzabrutinib among the medicines taken, each a report of something that happened, not proof the medicine caused it; 3 are coded as a death and 55 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, 9 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

  • Platelet Count Decreased99
  • Diarrhoea (named in the label)97
  • Nausea (named in the label)73
  • Drug Ineffective (a use or a product term, not a reaction)55
  • Headache (named in the label)32
  • Fatigue31
  • Abdominal Discomfort27
  • Product Use In Unapproved Indication (a use or a product term, not a reaction)26
  • Vomiting (named in the label)21
  • Dizziness (named in the label)18
  • Platelet Count Abnormal16
  • Arthralgia (named in the label)15
  • Asthenia14
  • Abdominal Pain Upper12
  • Off Label Use (a use or a product term, not a reaction)12
  • Abdominal Pain (named in the label)11
  • Dyspepsia (named in the label)11
  • Epistaxis10
  • Inappropriate Schedule Of Product Administration (a use or a product term, not a reaction)10
  • Pain9
  • Rash9
  • Urinary Tract Infection (named in the label)9
  • Vision Blurred9
  • Constipation8
  • Contusion8

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Rilzabrutinib: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions