What the label lists and what reports show
Arsenic trioxide side effects
Arsenic trioxide's FDA label: “The most common adverse reactions (> 30%) are nausea, cough, fatigue, pyrexia, headache, abdominal pain, vomiting, tachycardia, diarrhea, dyspnea, hypokalemia, leukocytosis, hyperglycemia, hypomagnesemia, insomnia, dermatitis, edema, QTc prolongation, rigors …” FAERS holds 1,138 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 differentiation syndrome (189 reports).
- Generic listed
- A presentation discontinued
- Boxed warning
Check it at the source: the arsenic trioxide FDA label on DailyMed (effective July 23, 2021, Amneal Pharmaceuticals LLC); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (> 30%) are nausea, cough, fatigue, pyrexia, headache, abdominal pain, vomiting, tachycardia, diarrhea, dyspnea, hypokalemia, leukocytosis, hyperglycemia, hypomagnesemia, insomnia, dermatitis, edema, QTc prolongation, rigors, sore throat, arthralgia, paresthesia, and pruritus.
Table 4: Adverse Reactions (≥ 5%) in Patients with Relapsed or Refractory APL Who Received Arsenic Trioxide Injection in Study PLRXAS01
This table is printed in the Arsenic Trioxide label published by Fresenius Kabi USA, LLC of August 21, 2025; the label quoted above does not print one.
| Body System Adverse reaction | Any Grade Adverse Reactions | Grade ≥3 Adverse Reactions |
|---|---|---|
| Nausea | 30 | 75 |
| Vomiting | 23 | 58 |
| Diarrhea | 21 | 53 |
| Sore throat | 14 | 35 |
| Anorexia | 9 | 23 |
| Appetite decreased | 6 | 15 |
| Loose stools | 4 | 10 |
| Dyspepsia | 4 | 10 |
| Oral blistering | 3 | 8 |
| Fecal incontinence | 3 | 8 |
| Gastrointestinal hemorrhage | 3 | 8 |
| Dry mouth | 3 | 8 |
| Abdominal tenderness | 3 | 8 |
| Diarrhea hemorrhagic | 3 | 8 |
| Abdominal distension | 3 | 8 |
| Cough | 26 | 65 |
| Epistaxis | 10 | 25 |
| Post nasal drip | 5 | 13 |
| Wheezing | 5 | 13 |
| Decreased breath sounds | 4 | 10 |
| Crepitations | 4 | 10 |
| Rales | 4 | 10 |
| Hemoptysis | 3 | 8 |
| Tachypnea | 3 | 8 |
| Rhonchi | 3 | 8 |
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: Differentiation Syndrome [see Warnings and Precautions (5.1) ] Cardiac Conduction Abnormalities [see Warnings and Precautions (5.2) ] Encephalopathy [see Warnings and Precautions (5.3) ] Hepatotoxicity [see Warnings and Precautions (5.4) ] Carcinogenesis [see Warnings and Precautions (5.5) ] The most common adverse reactions (> 30%) are nausea, cough, fatigue, pyrexia, headache, abdominal pain, vomiting, tachycardia, diarrhea, dyspnea, hypokalemia, leukocytosis, hyperglycemia, hypomagnesemia, insomnia, dermatitis, edema, QTc prolongation, rigors, sore throat, arthralgia, paresthesia, and pruritus. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Amneal Pharmaceuticals at 1-877-835-5472 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. Relapsed or Refractory APL Safety information was available for 52 patients with relapsed or refractory APL who participated in clinical trials of arsenic trioxide. …
Source: FDA drug label, Amneal Pharmaceuticals LLC, effective July 23, 2021 (SPL set 5845022e-8c01-451b-ae49-a28e58c5f845), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,138 reports list arsenic trioxide among the medicines taken, each a report of something that happened, not proof the medicine caused it; 145 are coded as a death and 400 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, 12 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?
- Arsenic trioxide: 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