The US Food and Drug Administration has added a boxed warning to ferric carboxymaltose injection, sold as Injectafer, describing the risk of symptomatic hypophosphatemia—abnormally low phosphate levels in the blood.
Who may face greater risk
The FDA communication highlights patients receiving repeat treatment and those with risk factors for low phosphate. The agency recommends monitoring phosphate in at-risk patients and in anyone receiving another course within three months of the previous treatment.
Ferric carboxymaltose is an intravenous iron treatment used for certain patients with iron deficiency. A boxed warning is the FDA’s most prominent label warning, but it does not mean the medicine should never be used. It means clinicians and patients need clear information about a serious risk.
Symptoms can be mistaken for anaemia
Low phosphate can produce muscle weakness, bone pain, fatigue and, in severe or prolonged cases, bone complications. Some symptoms overlap with the condition for which intravenous iron is given, making laboratory assessment important when problems persist or worsen.
Patients should not discontinue medically necessary treatment on their own. Instead, they should ask their treating professional whether phosphate testing is appropriate and report new or worsening symptoms promptly.
Label change strengthens monitoring
The FDA’s September 1 update adds explicit monitoring advice and brings greater visibility to a risk already discussed in clinical literature. Healthcare teams should review cumulative exposure, nutritional status and conditions that affect phosphate metabolism.
This report is general information and is not individual medical advice. Decisions about intravenous iron should be based on a clinician’s assessment of benefits, alternatives and the patient’s specific risk factors.
