Siklos helps prevent painful crises linked to sickle cell disease. But between 100 mg and 1000 mg, the dose difference is considerable. The Agency reiterates the essential precautions to avoid further confusion.
A dosage error which can have serious consequences
In a press release published on August 25, 2026, the National Medicines Safety Agency (ANSM) reports a new case of serious medication error linked to confusion between the two dosages of Siklos100 mg and 1000 mg, when dispensed in pharmacies.
“We have been alerted of a new case of serious medication error which occurred following a confusion between the two dosages of the Siklos medication (100 mg and 1000 mg) during dispensing in the pharmacy.”indicates the ANSM.
Siklos containshydroxycarbamide. It is indicated in adults and children over 2 years of age with sickle cell disease to prevent recurrent painful vaso-occlusive crises, as well as acute chest syndrome, a potentially serious complication.
Confusion can lead to an overdose or underdosewith potentially significant consequences for the patient.
100 mg or 1000 mg: the two presentations to distinguish
To limit errors, the two presentations have different characteristics:
- Siclos 100 mg : “gold” box and scored tablet engraved with the letter Hfor “hundred”;
- Siclos 1000 mg : “red” box and larger tablet, quadriseparable, engraved with the letter Tfor “thousand”.
But beyond these visual elements, the ANSM insists on the need to systematically check the prescribed dosage.
© ansm
This precaution is particularly important for a treatment whose prescription must take into account parameters such as the age and weight of the patient.
A form to present to the pharmacist
The ANSM recalls the existence of several documents intended to secure the use of Siklos: a guide for prescribers, a guide for patients and a help sheet for understanding the prescriptiongiven by the doctor and presented to the pharmacist.
When prescribing, the doctor must specify the dosage, as well as the weight and age of the patient, explain the dosage and provide these information documents.
For his part, the pharmacist must request the form and
check that the dosage delivered corresponds to that which was prescribed. “If in doubt, contact the prescriber before any delivery.”recommends the ANSM.
For patients, a simple reflex
This alert does not mean that treatment should be interrupted. Above all, it reminds us of the importance of careful checking, particularly when the drug exists in two such different dosages.
Before taking Siklos, patients and their loved ones can check the dosage written on the box. In case of doubt, unusual change in presentation or question about dosage, it is better ask for confirmation from the pharmacist or doctor.
For people who already live with the daily constraints of sickle cell anemia, securing treatment must above all allow them to care with greater peace of mind.