What the label lists and what reports show
Niraparib side effects
Niraparib's FDA label: “Most common adverse reactions (incidence ≥10%) in patients who received ZEJULA were nausea, thrombocytopenia, anemia, fatigue, constipation, musculoskeletal pain, abdominal pain, vomiting, neutropenia, decreased appetite, leukopenia, insomnia, headache …” FAERS holds 22,065 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 nausea (5,785 reports).
- No generic listed
Check it at the source: the niraparib FDA label on DailyMed (effective July 28, 2026, GlaxoSmithKline LLC); 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 ZEJULA?ZEJULA may cause serious side effects, including: • See “What is the most important information I should know about ZEJULA?” The most common side effects of ZEJULA include: • nausea • tiredness • constipation • pain in your muscles and back • pain in the stomach area • vomiting • loss of appetite • trouble sleeping • headache • shortness of breath • rash • diarrhea • cough • dizziness • changes in the amount or color of your urine • urinary tract infection • low levels of magnesium in the blood Your healthcare provider may change your dose, temporarily stop treatment, or permanently stop treatment with ZEJULA if you have certain side effects. These are not all the possible side effects of ZEJULA. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Source: FDA drug label, GlaxoSmithKline LLC, effective July 28, 2026 (SPL set b7f675e2-159c-490c-b6f4-3f16d9492b7d), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (incidence ≥10%) in patients who received ZEJULA were nausea, thrombocytopenia, anemia, fatigue, constipation, musculoskeletal pain, abdominal pain, vomiting, neutropenia, decreased appetite, leukopenia, insomnia, headache, dyspnea, rash, diarrhea, hypertension, cough, dizziness, acute kidney injury, urinary tract infection, and hypomagnesemia.
Table 8. Adverse Reactions Reported in ≥10% of Patients Receiving ZEJULA in NOVA gBRCAmut Cohort
| Reaction | ZEJULA (n = 136) % | Placebo (n = 65) % | ZEJULA (n = 136) % | Placebo (n = 65) % |
|---|---|---|---|---|
| Nausea | 77 | 34 | 5 | 3 |
| Vomiting | 40 | 15 | 4 | 0 |
| Constipation | 38 | 18 | 0.7 | 2 |
| Dyspepsia | 17 | 12 | 0 | 0 |
| Dry mouth | 13 | 3 | 0.7 | 0 |
| Thrombocytopenia b | 71 | 5 | 38 | 2 |
| Anemia c | 52 | 8 | 33 | 0 |
| Neutropenia d | 31 | 9 | 21 | 3 |
| Fatigue e | 61 | 35 | 8 | 2 |
| Headache | 35 | 8 | 0.7 | 0 |
| Dizziness | 18 | 9 | 0 | 0 |
| Dysgeusia | 13 | 2 | 0 | 0 |
| Decreased appetite | 22 | 14 | 0 | 0 |
| Hypertension | 21 | 8 | 8 | 5 |
| Insomnia | 18 | 6 | 0.7 | 0 |
| Anxiety | 10 | 11 | 0.7 | 0 |
| Dyspnea | 17 | 5 | 2 | 0 |
| Cough | 16 | 2 | 0 | 0 |
| Nasopharyngitis | 13 | 5 | 0 | 0 |
| Back pain | 16 | 11 | 0.7 | 0 |
| Urinary tract infection | 11 | 9 | 0 | 2 |
| Rash | 10 | 2 | 0 | 0 |
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: • MDS/AML [see Warnings and Precautions ( 5.1 )] • Bone marrow suppression [see Warnings and Precautions ( 5.2 )] • Hypertension and cardiovascular effects [see Warnings and Precautions ( 5.3 )] • Posterior reversible encephalopathy syndrome [see Warnings and Precautions ( 5.4 )] Most common adverse reactions (incidence ≥10%) in patients who received ZEJULA were nausea, thrombocytopenia, anemia, fatigue, constipation, musculoskeletal pain, abdominal pain, vomiting, neutropenia, decreased appetite, leukopenia, insomnia, headache, dyspnea, rash, diarrhea, hypertension, cough, dizziness, acute kidney injury, urinary tract infection, and hypomagnesemia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact GlaxoSmithKline at 1-888-825-5249 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 with rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Source: FDA drug label, GlaxoSmithKline LLC, effective July 28, 2026 (SPL set b7f675e2-159c-490c-b6f4-3f16d9492b7d), via openFDA; the full label on DailyMed
What do FAERS reports show?
22,065 reports list niraparib among the medicines taken, each a report of something that happened, not proof the medicine caused it; 1,428 are coded as a death and 5,041 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 22 reactions below, 16 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?
- Niraparib: 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