FDA added a Boxed Warning for Injectafer-related symptomatic hypophosphatemia, while new recalls highlight hidden DNP and particulate contamination in IV products.

Most FDA adverse-event signals do not arrive with sirens. They appear in a quarterly table, FDA evaluates them, and sometimes the label changes.

Then there is Injectafer.

On September 1, 2026, the FDA added a Boxed Warning for symptomatic hypophosphatemia to ferric carboxymaltose injection, currently marketed as Injectafer. The warning follows years of labeling changes and, more recently, the drug's appearance in the January–March 2026 FDA Adverse Event Monitoring System (AEMS) report as a potential safety signal under evaluation. [1] [2]

This one made the trip.

AEMS/FAERS signal → further FDA evaluation → Boxed Warning.

For pharmacovigilance, that sequence is worth watching. For clinicians, the message is more immediate: hypophosphatemia after ferric carboxymaltose can become a real toxicologic problem.

Injectafer: When Low Phosphate Stops Being a Footnote

Hypophosphatemia with ferric carboxymaltose is not newly discovered. FDA identified serious symptomatic cases in 2019; labeling changed in 2020, was strengthened in 2023 with monitoring recommendations and information about osteomalacia and fractures, and gained additional risk factors in 2025. [1]

Still, cases continued.

FDA says symptomatic hypophosphatemia continues to be reported despite earlier labeling changes. Its 2026 review included AEMS/FAERS, published literature, and Sentinel data. Cases occurred after single and multiple infusions; some patients required hospitalization and prolonged phosphate replacement. Severe or prolonged hypophosphatemia can cause weakness, pain, fatigue, tremor, confusion, seizures, arrhythmias, osteomalacia, and fractures. [1]

And then comes one number that deserves attention:

Serum phosphate was tested in fewer than 20% of ferric-carboxymaltose administration episodes captured in FDA Sentinel data. [1]

That does not mean every patient requires identical laboratory surveillance. FDA specifically recommends phosphate monitoring in patients at risk and before repeat courses given within three months.

But it does tell us something important: a clinically meaningful adverse effect may be easy to miss when nobody looks for it.

Why Does Ferric Carboxymaltose Lower Phosphate?

This is where the story gets more interesting than “iron infusion causes low phosphorus.”

Ferric carboxymaltose can increase biologically active fibroblast growth factor 23, or FGF23. FGF23 promotes renal phosphate wasting and reduces calcitriol, which can lower calcium and drive secondary hyperparathyroidism, adding another push toward phosphate loss.

In a large randomized trial comparing ferric carboxymaltose with ferumoxytol, hypophosphatemia below 2.0 mg/dL occurred in 50.8% of ferric-carboxymaltose recipients versus 0.9% of those receiving ferumoxytol. The physiologic substudy demonstrated a marked rise in intact FGF23 accompanied by renal phosphate wasting, reduced calcitriol and calcium, and increased PTH. [3]

So this is not mysterious phosphate evaporation.

It is a recognizable physiologic cascade.

The tricky part is the presentation. Fatigue and weakness after treatment can sound suspiciously like the iron deficiency that brought the patient to the infusion center in the first place. That is exactly why the new warning matters.

What FDA Is Recommending Now

FDA advises clinicians to correct pre-existing hypophosphatemia, check serum phosphate before repeat courses in patients at risk or when another course is given within three months, monitor patients at risk for chronic hypophosphatemia, and treat clinically significant cases as medically indicated. FDA also says permanent discontinuation should be considered for severe symptomatic or persistent hypophosphatemia. [1]

Monitoring matters. Recognition matters. And no, a Boxed Warning does not mean every Injectafer infusion is dangerous; it means the risk is serious enough to be communicated prominently and monitored appropriately.

A Clean Pharmacovigilance Example

The January–March 2026 AEMS table listed Injectafer → hypophosphatemia → “FDA is evaluating the need for regulatory action.” [2]

Now we have the answer: the Boxed Warning is the regulatory action.

That does not mean FAERS or AEMS by itself proved causality. FDA explicitly warns against interpreting inclusion in a quarterly signal table that way. Spontaneous reporting systems generate signals; they do not provide clean incidence estimates, denominator-controlled risk calculations, or automatic proof that a drug caused an event. [4]

MedicalToxic explains these limitations in What Is FAERS and Why It Matters in Medical Toxicology.

A signal is not a verdict. But a good signal can start an investigation, and additional surveillance, literature, mechanistic evidence, and clinical cases can move the issue forward.

This is pharmacovigilance doing what pharmacovigilance is supposed to do.

What Is Happening With the Rest of the 2026 AEMS Signals?

The curated FDA safety-signal page still lists only January–March 2026, while the raw April–June 2026 AEMS data files were posted July 29. [4] [5]

Other January–March signals remain under evaluation. They are signals, not established causal adverse reactions.

Lipofit Extreme 2.0: A “Fat Burner” Containing DNP and Fluoxetine

The other major toxicology story comes from a very different corner of FDA surveillance.

On August 31, FDA posted a nationwide consumer-level recall of Lipofit Extreme Fat Burner 2.0. The daytime tablets contained undeclared fluoxetine. The nighttime tablets contained undeclared 2,4-dinitrophenol, or DNP. [6]

That is not a small labeling discrepancy.

DNP is a mitochondrial uncoupler: energy from oxidative metabolism is dissipated as heat rather than efficiently captured as ATP. Significant poisoning can produce diaphoresis, tachycardia, tachypnea, severe hyperthermia, seizures, cardiovascular collapse, and death. There is no established specific antidote. [7]

DNP does not need much help being dangerous.

The undeclared fluoxetine adds serotonergic toxicity, seizure, bleeding, and drug-interaction concerns. For clinical context, see Serotonin Syndrome (Serotonin Toxicity): Symptoms, Diagnosis, Drug Interactions, and Treatment.

FDA had already warned consumers about Lipofit in June. The August 31 development is different: the company initiated a nationwide recall. No known adverse events were reported at the time of the announcement. [8] [6]

Fluoxetine for the morning and DNP for the evening: calling that a “dietary supplement” was doing some heroic linguistic work.

IV Saline Recalls: When the Problem Is What Is Floating in the Bag

Two additional recalls concern something clinicians use every day: 0.9% sodium chloride injection.

FDA's B. Braun notice, updated September 3, covers three lots of 100 mL 0.9% Sodium Chloride Injection and identifies particulate matter including iron oxide, inorganic, cellulose, or polystyrene particulate matter. No serious injuries, deaths, or other adverse events were reported. [9]

FDA also posted Baxter's recall of two 500 mL saline lots because of potential fiberglass particulate matter; no associated adverse events were reported as of August 25. [10]

Intravenous particulate matter can cause vascular occlusion, pulmonary emboli, phlebitis, immune activation, hemolysis, and organ dysfunction. [9] [10]

Particle contamination in an IV solution is not a cosmetic defect. The hazard comes from unintended foreign material delivered directly into the vascular system.

Different mechanism. Same principle: route matters.

Are Adverse-Event Reports Suddenly Rising?

This part deserves restraint. FDA says symptomatic hypophosphatemia continues to be reported despite previous labeling changes, but that does not establish rising incidence or an increasing FAERS reporting rate.

Don’t bury the lead, but don’t manufacture one either.

The Bigger Lesson From This FDA Update

The bigger story is the path the evidence followed: a known adverse effect persisted, AEMS identified a potential signal, and FDA combined multiple evidence streams before escalating the warning.

Lipofit shows a different problem—undeclared pharmacologically active substances, including a potentially lethal mitochondrial toxin—while the saline recalls remind us that sometimes the toxicology is the thing that was never supposed to be in the bag.

For suspected poisoning or a potentially serious exposure in the United States, Poison Control can be reached at 1-800-222-1222. Severe symptoms such as seizures, altered mental status, severe hyperthermia, cardiovascular instability, or respiratory compromise require emergency medical evaluation. For more on poison-center decision support, see The Role of Poison Center Calls: Managing Poisoning Cases from Emergency Calls to Critical Decisions.

References

1. U.S. Food and Drug Administration. (2026, September 1). FDA Adds Boxed Warning to Labeling for Ferric Carboxymaltose Injection (Injectafer) to Describe Risk of Low Phosphate Levels.

2. U.S. Food and Drug Administration. (2026). January–March 2026: New Safety Information or Potential Signals of Serious Risks Identified by the FDA Adverse Event Monitoring System (AEMS).

3. Wolf, M., Chertow, G. M., Macdougall, I. C., Kaper, R., Krop, J., & Strauss, W. (2018). Randomized trial of intravenous iron-induced hypophosphatemia. JCI Insight, 3(23), e124486. https://doi.org/10.1172/jci.insight.124486

4. U.S. Food and Drug Administration. (2026). New Safety Information or Potential Signals of Serious Risks Identified from the FDA Adverse Event Monitoring System (AEMS).

5. U.S. Food and Drug Administration. (2026). AEMS Quarterly Data Extract Files.

6. U.S. Food and Drug Administration. (2026, August 31). Ana Salazar Modela Tu Cuerpo Inc. Issues Nationwide Voluntary Recall of Lipofit Extreme Fat Burner 2.0 Due to Presence of Undeclared Fluoxetine and 2,4-Dinitrophenol (DNP).

7. Grundlingh, J., Dargan, P. I., El-Zanfaly, M., & Wood, D. M. (2011). 2,4-Dinitrophenol (DNP): A weight loss agent with significant acute toxicity and risk of death. Journal of Medical Toxicology, 7(3), 205–212. https://doi.org/10.1007/s13181-011-0162-6

8. U.S. Food and Drug Administration. (2026). Lipofit Extreme 2.0 Fat Burner may be harmful due to hidden drug ingredients.

9. U.S. Food and Drug Administration. (2026, updated September 3). B. Braun Medical Inc. Issues Voluntary Nationwide Recall of 0.9% Sodium Chloride Injection USP, 100 mL, in a 150 mL PAB® Container Due to the Presence of Particulate Matter.

10. U.S. Food and Drug Administration. (2026, August 26). Baxter Issues Voluntary Nationwide Recall for Two Lots of 0.9% Sodium Chloride Injection Due to Potential Presence of Particulate Matter.