What is Considered an Iron Overdose?

November 15, 2025 •

4 min read

Iron overdose is a leading cause of poisoning deaths in children under six, largely due to iron supplements being mistaken for candy. A specific amount of elemental iron per kilogram of body weight is considered a toxic or lethal dose, rather than a fixed number of pills. The severity hinges on the ingested elemental iron amount, not the total weight of the supplement pill.

Quick Summary

An iron overdose is defined by the amount of elemental iron ingested relative to body weight, with toxicity ranging from mild GI issues to lethal systemic effects. It progresses through multiple stages, beginning with gastrointestinal symptoms and potentially leading to shock, organ failure, or intestinal scarring in severe cases. Prompt medical treatment is crucial.

Key Points

Elemental Iron is Key: An overdose is determined by the amount of elemental iron ingested per kilogram of body weight, not the number of pills.
Ingestion Thresholds: Ingesting over 60 mg/kg of elemental iron can cause systemic toxicity, while doses over 120 mg/kg are potentially lethal.
Five-Stage Progression: Iron poisoning typically follows five stages, including a dangerous latent phase where symptoms temporarily improve before worsening.
Danger to Children: Iron overdose is especially life-threatening for young children, who can mistake supplements for candy.
Immediate Medical Aid: Any suspected iron overdose requires an immediate call to poison control and evaluation in a hospital setting.
Do Not Induce Vomiting: Vomiting should not be induced at home following an overdose, as it can complicate medical assessment.
Prevention is Critical: Safe storage of all iron-containing products away from children is the best prevention strategy.

Understanding Elemental Iron and Toxic Doses

Determining what constitutes an iron overdose is not based on the number of pills, but rather the amount of elemental iron ingested relative to a person's body weight. Each iron salt, such as ferrous sulfate or ferrous fumarate, contains a different percentage of elemental iron. This is a critical factor, as a smaller, high-potency tablet could contain more elemental iron than a larger, low-potency one. Generally, doses are categorized by the amount of elemental iron per kilogram (mg/kg) of body weight.

Less than 20 mg/kg: Typically asymptomatic or causes only minor, temporary gastrointestinal (GI) upset.
20-40 mg/kg: Primarily causes GI symptoms like abdominal pain, vomiting, and diarrhea.
40-60 mg/kg: Symptoms are generally confined to the GI tract but the potential for systemic toxicity increases.
60-120 mg/kg: Ingestion within this range has a high potential for systemic toxicity, affecting organs beyond the GI tract.
Greater than 120 mg/kg: Considered a potentially lethal dose, requiring immediate and aggressive medical intervention.

It is vital to note that deaths have been documented with doses lower than the typically estimated lethal range, underscoring the seriousness of any significant iron ingestion. In children, even five or six high-potency prenatal vitamins can be fatal due to their small body size.

The Stages of Iron Poisoning

Acute iron poisoning typically progresses through several distinct stages, though not all stages may be apparent in every case.

Stage 1: Gastrointestinal Toxicity (0–6 hours): Symptoms are caused by the corrosive effect of iron on the stomach and intestinal lining. This phase is marked by severe abdominal pain, vomiting (sometimes with blood), and diarrhea. Significant fluid and blood loss can lead to hypovolemic shock.
Stage 2: Quiescent or Latent Phase (6–24 hours): In this deceptive phase, GI symptoms may temporarily improve or resolve. The iron is absorbed and redistributes throughout the body, but cellular toxicity is silently underway. This false sense of security can lead to delayed treatment, with catastrophic consequences.
Stage 3: Systemic Toxicity (12–48 hours): The iron's toxic effects become widespread, damaging cellular function. This stage is characterized by multi-organ failure, metabolic acidosis, shock, and seizures. The liver and heart are particularly vulnerable to this cellular damage.
Stage 4: Hepatic Necrosis (2–5 days): The liver, which processes excess iron, begins to fail. Jaundice (yellowing of the skin), bleeding problems, and hypoglycemia can occur. Liver failure can be fatal at this point.
Stage 5: Gastrointestinal Scarring (2–5 weeks): Long-term survivors of severe iron poisoning may develop scarring and strictures in the stomach or intestines, which can cause chronic abdominal pain, vomiting, and potential bowel obstruction.

Management and Treatment of an Overdose

If an iron overdose is suspected, immediate medical attention is required. Management depends on the severity and includes supportive care, decontamination, and chelation therapy.

Comparison of Overdose Severity and Treatment


Level of Ingestion	Estimated Elemental Iron (mg/kg)	Clinical Presentation	Management & Treatment
Asymptomatic/Mild	< 20 mg/kg	No symptoms or minor GI upset within 6 hours.	Observation in a healthcare setting for at least 6 hours.
Moderate	20-60 mg/kg	Prominent GI symptoms (vomiting, diarrhea) but typically no systemic signs.	Hospital evaluation, including blood tests and abdominal X-ray. Supportive care with IV fluids may be needed.
Severe	> 60 mg/kg	Systemic toxicity signs (shock, metabolic acidosis, lethargy).	Aggressive supportive care (IV fluids), whole bowel irrigation, and intravenous chelation therapy with deferoxamine.
Potentially Lethal	> 120 mg/kg	Severe, life-threatening systemic toxicity; organ failure, coma.	Intensive care unit admission, aggressive whole bowel irrigation, and continuous chelation therapy. Surgical removal of tablets may be considered.

What to Do in Case of an Overdose

Call for Help Immediately: If you suspect an overdose, contact a poison control center or emergency services right away. The national Poison Help hotline is 1-800-222-1222.
Do Not Induce Vomiting: Do not attempt to induce vomiting with syrup of ipecac, as this can worsen the patient's condition and make clinical assessment more difficult.
Gather Information: Be prepared to provide details about the type of product ingested, the amount, the estimated time of ingestion, and the patient's age and weight.
Seek Hospital Care: All suspected or confirmed significant iron ingestions require immediate hospital evaluation, especially for children or intentional overdoses.

Conclusion

Understanding what is considered an iron overdose involves recognizing the critical role of elemental iron dosage per kilogram of body weight. The severity can range from asymptomatic to lethal, and the progression often follows a multi-stage course that includes a deceptively calm latent phase before serious systemic toxicity manifests. Due to the high risk of organ damage and fatality, especially in young children, any suspected overdose should be treated as a medical emergency. Early recognition, immediate contact with poison control, and rapid hospital intervention are the most critical steps to ensuring a positive outcome. Educating households on proper storage of all medications, including prenatal vitamins and supplements, is key to prevention.

Preventative Measures

To prevent accidental iron overdose, especially in children:

Keep all iron supplements and multivitamins in secure, child-proof containers and out of a child's sight and reach.
Be aware that prenatal vitamins contain high levels of iron and pose a significant risk to toddlers.
Never refer to medications as 'candy,' even if they are chewable or flavored, as this can confuse children.
If a child has a potential exposure, regardless of symptoms, seek immediate professional medical advice.

Frequently Asked Questions

Iron is highly corrosive to the gastrointestinal tract, causing bleeding and fluid loss. Once absorbed, excessive iron is a cellular toxin that damages vital organs like the heart and liver by interfering with metabolic processes.

While children's chewable vitamins generally contain low amounts of iron and are less likely to cause serious poisoning, concentrated supplements like adult or prenatal vitamins are very dangerous for children. The small size of a child means a few tablets can constitute a toxic or lethal dose.

The initial symptoms, typically appearing within six hours, include severe abdominal pain, nausea, vomiting (potentially with blood), and diarrhea. A metallic taste in the mouth is also possible.

Treatment depends on severity. It may involve supportive care with intravenous fluids, whole bowel irrigation to flush out remaining tablets, and chelation therapy using a medication like deferoxamine to bind the iron in the blood.

The quiescent, or latent, phase is a deceptive period 6 to 24 hours after an overdose where initial gastrointestinal symptoms improve. This is dangerous because systemic toxicity is still developing internally, and the patient may appear to be recovering.

Yes, even if a person survives a severe overdose, they may experience long-term complications. These can include gastrointestinal scarring leading to bowel obstruction and chronic abdominal issues, as well as permanent liver damage.

An ingestion over 120 mg/kg of elemental iron is considered potentially lethal. This level of toxicity can cause shock, liver failure, coma, seizures, and death without immediate and aggressive medical intervention in an intensive care setting.