What the label lists and what reports show
Hydroxyurea side effects
Hydroxyurea's FDA label: “Most common adverse reactions (≥30%) are hematological, gastrointestinal symptoms, and anorexia.” FAERS holds 21,023 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 (1,547 reports).
- Generic listed
Check it at the source: the hydroxyurea FDA label on DailyMed (effective September 15, 2025, Waylis Therapeutics 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 DROXIA?DROXIA may cause serious side effects, including: See " What is the most important information I should know about DROXIA? " Skin ulcers and death of tissue (gangrene) have happened in people who take DROXIA. This has happened most often in people who receive interferon therapy or have a history of interferon therapy. Your healthcare provider will stop treatment with DROXIA if you develop any skin ulcers. Enlarged red blood cells (macrocytosis). Macrocytosis is common in people who take DROXIA and can make it difficult to detect a decrease of folic acid. Your healthcare provider may prescribe a folic acid supplement for you. Hemolytic Anemia, the fast breakdown of red blood cells, has happened in people who take DROXIA. Tell your healthcare provider if you develop yellowing of your skin (jaundice) or blood in your urine. […]
Source: FDA drug label (DROXIA), Waylis Therapeutics LLC, effective September 12, 2025 (SPL set 4ad13dc6-a2ab-4308-96b3-7c642c92cc23), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥30%) are hematological, gastrointestinal symptoms, and anorexia.
Table 3. Adverse Reactions Reported in Pediatric Patients Aged 10 Months and Older Enrolled in HUPK
This table is printed in the XROMI label published by Nova Laboratories, Ltd. of February 2, 2026; the label quoted above does not print one.
| Body System Adverse Reactions | 10 Months–<2 Years (n=6)% | 2 –<6 Years (n=16)% | 6 –<18 Years (n=10)% | Overall (n=32)% |
|---|---|---|---|---|
| Neutropenia | 3 (50) | 1 (6) | 0 | 4 (13) |
| Thrombocytopenia | 2 (33) | 1 (6) | 0 | 3 (9) |
| Diarrhea | 1 (17) | 0 | 0 | 1 (3) |
| GGT Increased | 0 | 0 | 1(10) | 1 (3) |
| Absolute Reticulocyte Count Decreased | 1 (17) | 0 | 0 | 1 (3) |
| Alopecia | 0 | 1 (6) | 0 | 1 (3) |
| Nail Discolouration | 0 | 0 | 1 (10) | 1 (3) |
| Rash | 0 | 0 | 1 (10) | 1 (3) |
| Rash Popular | 0 | 1 (6) | 1 (10) | 2 (6) |
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 in detail in other labeling sections: Myelosuppression [see Warnings and Precautions (5.1) ] Hemolytic anemia [see Warnings and Precautions (5.2) ] Malignancies [see Warnings and Precautions (5.3) ] Vasculitic toxicities [see Warnings and Precautions (5.5) ] Risks with concomitant use of antiretroviral drugs [see Warnings and Precautions (5.7) ] Radiation recall [see Warnings and Precautions (5.8) ] Macrocytosis [see Warnings and Precautions (5.9) ] Pulmonary Toxicity [see Warnings and Precautions (5.10) ] Most common adverse reactions (≥30%) are hematological, gastrointestinal symptoms, and anorexia. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Waylis Therapeutics LLC at 1-844-200-7910 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Postmarketing Experience The following adverse reactions have been identified during post-approval use of HYDREA. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency.
Source: FDA drug label, Waylis Therapeutics LLC, effective September 15, 2025 (SPL set 8d41152f-a98a-4abc-afdf-a909012434a0), via openFDA; the full label on DailyMed
What do FAERS reports show?
21,023 reports list hydroxyurea among the medicines taken, each a report of something that happened, not proof the medicine caused it; 3,145 are coded as a death and 7,991 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, 11 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?
- Hydroxyurea: 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