What the label lists and what reports show
Palbociclib side effects
Palbociclib's FDA label: “Most common adverse reactions (incidence ≥20%) in combination with either letrozole or fulvestrant, including laboratory abnormalities, were white blood cell count decreased, neutrophils decreased, blood creatinine increased, hemoglobin decreased, platelets …” FAERS holds 94,825 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 (15,729 reports).
- No generic listed
- A presentation discontinued
Check it at the source: the palbociclib FDA label on DailyMed (effective July 2, 2026, Pfizer Laboratories Div Pfizer 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 IBRANCE?IBRANCE may cause serious side effects. See " What is the most important information I should know about IBRANCE? " The most common side effects of IBRANCE when used with either letrozole or fulvestrant include: • Low red blood cell counts and low platelet counts. […]
Source: FDA drug label, Pfizer Laboratories Div Pfizer Inc, effective July 2, 2026 (SPL set fecbdd7d-b729-41b5-9872-231b8fe104ce), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (incidence ≥20%) in combination with either letrozole or fulvestrant, including laboratory abnormalities, were white blood cell count decreased, neutrophils decreased, blood creatinine increased, hemoglobin decreased, platelets decreased, infections, aspartate aminotransferase increased, alanine aminotransferase increased, fatigue, nausea, stomatitis, diarrhea, and alopecia.
Table 10. Adverse Reactions (≥10%) in PATINA
| Reaction | All Grades (%) | Grade 3 (%) | Grade 4 (%) | All Grades (%) | Grade 3 (%) | Grade 4 (%) |
|---|---|---|---|---|---|---|
| Diarrhea | 70 | 10 | 0 | 37 | 1.2 | 0 |
| Stomatitis Stomatitis includes the following PTs: Aphthous ulcer, Cheilitis, Glossitis,… | 44 | 3.5 | 0 | 11 | 0 | 0 |
| Nausea | 30 | 0.4 | 0 | 15 | 0.4 | 0 |
| Abdominal pain | 17 | 1.2 | 0 | 6 | 2 | 0 |
| Vomiting | 15 | 0.8 | 0 | 9 | 1.2 | 0 |
| Constipation | 13 | 0 | 0 | 9 | 0 | 0 |
| Infections Infections includes any reported PTs that are part of the System Organ Class… | 64 | 7 | 0.8 | 43 | 4 | 0.8 |
| Fatigue | 32 | 3.5 | 0 | 21 | 0 | 0 |
| Asthenia | 27 | 1.9 | 0 | 21 | 0 | 0 |
| Pyrexia | 17 | 0.8 | 0.4 | 6 | 0.4 | 0 |
| Headache | 26 | 1.5 | 0 | 18 | 0.8 | 0 |
| Dizziness | 14 | 0.8 | 0 | 9 | 0 | 0 |
| Peripheral neuropathy | 14 | 0 | 0 | 8 | 0.4 | 0 |
| Rash Rash includes the following PTs: Rash, Rash maculo-papular, Rash pruritic, Rash… | 22 | 0 | 0 | 17 | 0 | 0 |
| Pruritus | 21 | 1.5 | 0 | 17 | 0 | 0 |
| Dry skin | 10 | 0 | 0 | 6 | 0 | 0 |
| Muscle spasms | 20 | 0.4 | 0 | 11 | 0 | 0 |
| Epistaxis | 19 | 0 | 0 | 6 | 0 | 0 |
| Cough | 16 | 0 | 0 | 11 | 0 | 0 |
| Dyspnea | 10 | 0.8 | 0 | 9 | 0.8 | 0 |
| Decreased appetite | 13 | 0.8 | 0 | 5 | 0 | 0 |
| Vulvovaginal dryness | 11 | 0.4 | 0 | 4 | 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: • Neutropenia [see Warnings and Precautions (5.1) ] • ILD/Pneumonitis [see Warnings and Precautions (5.2) ] Most common adverse reactions (incidence ≥20%) in combination with either letrozole or fulvestrant, including laboratory abnormalities, were white blood cell count decreased, neutrophils decreased, blood creatinine increased, hemoglobin decreased, platelets decreased, infections, aspartate aminotransferase increased, alanine aminotransferase increased, fatigue, nausea, stomatitis, diarrhea, and alopecia. ( 6.1 ) The most common adverse reactions (incidence ≥20%) in combination with inavolisib and fulvestrant, including laboratory abnormalities, were neutrophils decreased, hemoglobin decreased, fasting glucose increased, platelets decreased, lymphocytes decreased, stomatitis, diarrhea, calcium decreased, fatigue, potassium decreased, creatinine increased, alanine aminotransferase (ALT) increased, nausea, sodium decreased, magnesium decreased, rash, decreased appetite, COVID-19 infection, and headache.
Source: FDA drug label, Pfizer Laboratories Div Pfizer Inc, effective July 2, 2026 (SPL set fecbdd7d-b729-41b5-9872-231b8fe104ce), via openFDA; the full label on DailyMed
What do FAERS reports show?
94,825 reports list palbociclib among the medicines taken, each a report of something that happened, not proof the medicine caused it; 10,577 are coded as a death and 14,349 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 23 reactions below, 18 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?
- Palbociclib: 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