This grade answers one narrow question: how strong is the public evidence and safety record behind this drug, and how clean is its money trail and court record? It is not a verdict on whether the drug is right for you.
WARNING: MYELOSUPPRESSION and MALIGNANCIES WARNING: MYELOSUPPRESSION and MALIGNANCIES See full prescribing information for complete boxed warning . Myelosuppression : SIKLOS may cause severe myelosuppression. Do not give if bone marrow function is markedly depressed. Monitor blood counts at baseline and throughout treatment. Interrupt treatment and reduce dose as necessary. ( 5.1 ) Malignancies : Hydroxyurea is carcinogenic. Advise sun protection and monitor patients for malignancies. ( 5.2 ) Myelosuppression: SIKLOS may cause severe myelosuppression. Monitor blood counts at baseline and throughout treatment. Interrupt treatment and reduce dose as necessary [see Warnings and Precautions (5.1) ] . Malignancies: Hydroxyurea is carcinogenic. Advise sun protection and monitor patients for malignancies [see Warnings and Precautions (5.2) ] .
® is indicated to reduce the frequency of painful crises and to reduce the need for blood transfusions in adult and pediatric patients, 2 years of age and older, with sickle cell anemia with recurrent moderate to severe painful crises SIKLOS is an antimetabolite, indicated to reduce the frequency of painful crises and to reduce the need for blood transfusions in adult and pediatric patients, 2 years of age and older, with sickle cell anemia with recurrent moderate to severe painful crises. ( 1 )
is contraindicated in: Patients who have demonstrated a previous hypersensitivity to hydroxyurea or any other component of its formulation [see Adverse Reactions (6) ]. Patients who have demonstrated a previous hypersensitivity to hydroxyurea or any other component of its formulation. ( 4 )
Embryo-Fetal toxicity: Can cause fetal harm. Advise of potential risk to a fetus and use of effective contraception. ( 5.3 , 8.1 , 8.3 ) Cutaneous vasculitic toxicities (incl. leg ulcers): Institute treatment and discontinue SIKLOS and/or reduce dose if this occurs. ( 5.4 ) Risks with concomitant use of antiretroviral drugs: Pancreatitis, hepatotoxicity, and neuropathy have occurred. Monitor for signs and symptoms patients with HIV infection using antiretroviral drugs; discontinue SIKLOS, and implement treatment. ( 5.5 ) Concomitant use with live virus vaccine: increased risk of severe infections. ( 5.6 ) Hemolytic Anemia: Monitor blood counts throughout treatment. If hemolysis persists, discontinue SIKLOS. ( 5.9 ) 5.1 Myelosuppression Hydroxyurea causes severe myelosuppression. Do not initiate treatment with hydroxyurea in patients if bone marrow function is markedly depressed. Bone marrow suppression may occur, and leukopenia is generally its first and most common manifestation. Thrombocytopenia and anemia occur less often, and are seldom seen without a preceding leukopenia. Some patients, treated at the recommended initial dose of 15 mg/kg/day in adults or 20 mg/kg/day in childr...
The following clinically significant adverse reactions are described elsewhere in the labeling: Myelosuppression [see Warnings and Precautions (5.1) ] Malignancies [see Warnings and Precautions (5.2) ] Vasculitic toxicities (including Leg Ulcers) [see Warnings and Precautions (5.4) ] Risks with concomitant use of antiretroviral drugs [see Warnings and Precautions (5.5) ] Risk with concomitant use of live virus vaccine [see Warnings and Precautions (5.6) ] Macrocytosis [see Warnings and Precautions (5.7) ] Hemolytic Anemia [see Warnings and Precautions (5.9) ] Most common adverse reactions to SIKLOS (incidence > 10%) include infections and neutropenia in children and infections and headache and dry skin in adults. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact the marketer Medunik at 1 844-884-5520 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trial 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 SIKLOS has been assessed i...
Warnings and Precautions, Test Interference ( 5.8 ) 11/2023 Drug interactions, Test Interference ( 7.3 ) 11/2023
Source: FDA SPL label for Siklos (Medunik), effective 20260107. Full label on DailyMed.
These are counts of reports people filed, not rates of harm. Anyone can file one, and nobody checks whether the drug was the cause. Millions of doses are taken for every report sent, so the useful part is how this drug compares with the average across all drugs.
| 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | 2026 |
|---|---|---|---|---|---|---|---|
| 1,695 | 1,957 | 2,019 | 1,923 | 1,724 | 1,382 | 1,260 | 560 |
6,081 reports blaming this drug for every million Medicare prescriptions filled, which is 2.2× the typical drug on this site. (3,199 reports in 2024–2026, against 526,088 Medicare fills in one year. This is the one number here that accounts for how many people take the drug.)
Source: the FDA's Adverse Event Reporting System (FAERS). Reports are voluntary and unverified. Drugs that are prescribed a lot, in the news, or in lawsuits attract more reports, so the percentages are compared with the whole database to correct for that partly, not fully.
Counts measure how much evidence exists and how transparent it is, not how big the benefit is. For that, ask your prescriber: if 100 people like me took this, how many would get better because of it, and how many would be harmed? (Doctors call these the "number needed to treat" and "number needed to harm.") It differs by condition and is the number drug ads leave out. Sources: PubMed, ClinicalTrials.gov.
In 2024, drug companies reported $4,353 in payments to US physicians and hospitals tied to this drug across 37 transactions (Xromi $3,500, Siklos $853).
No pending federal MDL names this drug or its brands.
Not named in any federal pharmaceutical settlement of $100M or more on record.
Sources: CMS Open Payments (Sunshine Act); Judicial Panel on Multidistrict Litigation pending docket list; DOJ settlements as tabulated on Wikipedia with links to the primary record. State-court and individual suits are not included.
| Product | Fills | $/fill |
|---|---|---|
| Hydroxyurea | 521,514 | $25 |
| Droxia | 3,444 | $48 |
| Siklos | 765 | $1,256 |
| Hydrea | 365 | $106 |
No same-class alternatives found in RxClass.