What is iron poisoning ?Iron poisoning is essentially an overdose of iron. Some iron in the diet is vital for good health. However, it is also highly toxic if too much is ingested (swallowed).
Who is at risk for iron poisoning?Iron poisoning mainly involves children younger than six years (although it does also occur in adults), who get hold of and swallow too many iron-containing pills. It is one of the most frequent causes of death by poisoning in children.
Iron poisoning occurs as commonly as it does because:
- Iron supplements are found in many homes with small children. It is available in numerous prescription and non-prescription oral forms, such as ferrous sulfate, ferrous gluconate and ferrous fumarate. It is also an ingredient of many mineral and multivitamin preparations for both children and adults. Pregnant women are often prescribed vitamins with high iron content.
- Many people are not aware that iron can be dangerous, and regard iron supplements as nutritional products rather than medications.
- Iron-containing medications are often in the form of pills that look like sweets to young children.
- Not all iron preparations have child-proof lids, and those that do are not always effective against children opening them.
How much iron causes iron poisoning?The amount of iron that will cause poisoning depends on the size of the person who has ingested it. Toxic effects start to occur at doses over 10-20 mg of iron per kilogram of body weight. Ingestions of over 50 mg/kg cause severe toxicity.
It is generally safe for adults to take iron supplements if directions on the product's label are followed. Current Recommended Dietary Allowances (RDAs) for iron are 15 mg per day for women of child-bearing age, 10 mg/day for men and post-menopausal women, and 30 mg/day for pregnant women.
Paediatric doses of elemental iron should be between 1-2 mg/kg three times a day. This equates to 10 mg/kg of ferrous sulphate and 16 mg/kg of ferrous gluconate if the doses are to correct an iron deficiency. If iron supplementation is being used in young children to prevent iron deficiency arising from an inadequate diet, then lower doses are used.
In general, particularly for adults, it is not advisable to take iron supplements unless a deficiency has been diagnosed. Children from poor socio-economic backgrounds are often placed on iron supplements because their diet is assumed to be poor in iron.
Symptoms and signs of iron poisoningSymptoms of iron poisoning usually begin within six hours of swallowing the iron (although they may occur as early as 20 minutes afterwards), and may include:
- Gastrointestinal (digestive tract) bleeding, which may cause blood in the vomit or stool
- Abdominal pain
- Pallor (looking pale), and bluish lips and fingernails
- Rapid breathing
- Weak, rapid pulse
- Low blood pressure
These symptoms may progress to shock, coma and death.
A child may show no symptoms initially. Sometimes, the child may appear to recover from the initial symptoms, but this is deceptive because a few hours later he or she can go into shock, with severe blood chemistry imbalance.
When too much iron enters the bloodstream, it travels to all the organs and can damage the stomach, liver, kidneys, lungs, blood vessels and brain.
Severe iron overdose can be divided into phases. In the early phase, half an hour to two hours after ingestion, the symptoms are:
- Vomiting blood (called haematemesis)
- Pain in the tummy
- Deranged electrolytes resulting in an acidotic blood chemistry
- Problems with blood clotting
This is followed by a period during which the person may appear, deceptively, to recover and stabilise. In severe poisoning, this period may be brief.
After this so-called quiescent period, 12 to 48 hours later, life-threatening signs and symptoms develop:
- Profuse vomiting of blood
- Passing of blood in the stools
- Possible perforation of the gut
- Collapse of the vascular system with dangerously low blood pressure
- Low blood sugar
- Lack of oxygen to the brain and other organs
- Fluid build up in the lungs
Towards the end of this phase, liver and kidney failure develops.
How is iron poisoning diagnosed?Take the medicine containers with you to the doctor or hospital. The doctor will physically examine your child and monitor him or her for several hours for symptoms. A normal physical exam and no symptoms for six hours means that the child experienced either little poisoning or did not in fact swallow any iron.
The doctor may take a blood sample from your child to determine the following levels:
- White blood cell count
- Serum glucose (blood sugar)
The doctor may also take an x-ray of your child’s abdomen to see if there are iron pills in the gastrointestinal tract, although sometimes the pills are present and do not show up on x-ray, or they may already be dissolved.
Laboratory and imaging tests are usually not sufficiently sensitive to detect poisoning, however. Some tests are also not fast enough for effective diagnosis and treatment.
How is iron poisoning treated? You may be telephonically instructed to induce emesis (vomiting) in your child at home by your doctor or poison control centre, unless the child is unconscious or having convulsions. The standard procedure for inducing emesis is as follows:
- Dose with ipecac syrup: 15ml or one tablespoon for children; 30 ml or two tablespoons for adults.
- Follow with half a glass of water for children or a glass of water for adults.
- Repeat once after half an hour if emesis has not occurred.
Do not attempt to induce vomiting without advice from a health professional, as this may hamper assessment of whether your child is iron toxic.
The doctor may alternatively give your child a strong laxative fluid to drink in order to clean the bowel and remove the iron.
Severe poisonings require intravenous chelation therapy: deferoxamine mesylate, a chemical that binds to the iron and then allows it to be excreted in the urine, is administered through a drip. Deferoxamine can also be given as an injection, but a drip is usually used as it allows the dose to be adjusted more easily.
Orogastric lavage, or pumping of the stomach, may be considered, but is usually only effective if performed within one hour of iron ingestion. Insertion of the lavage tube can cause complications, and the swallowed pills may not fit through the tube.
If ingestion of other medications (in addition to the iron) is suspected, the doctor may give the child activated charcoal to drink. Activated charcoal does not bind to iron but may absorb other medications.
What is the outcome of iron poisoning?Full recovery is likely in children who show no symptoms within six hours of ingestion of the iron. Those with symptoms may require more aggressive treatment, and monitoring for complications for some days or weeks afterwards.
Iron poisoning can progress through several stages. A hepatic stage, involving the liver, may develop two to five days after ingestion. Liver damage or failure is reflected in elevated liver enzymes.
Gastrointestinal scarring may also occur at a later stage. Four to six weeks after ingestion, the final stage manifests with early satiety (a feeling of fullness after eating) or nausea from gastrointestinal scarring and obstruction.
Death may occur even after a week from ingestion of excessive amounts of iron.
When to call the doctorIf you know or suspect your child has swallowed iron-containing tablets, even if he or she shows no symptoms, call your doctor or a poison control centre immediately. Sometimes, serious symptoms do not develop right away, and delayed treatment may not be effective. The contact numbers for poison control centres are listed under "Emergency Services" on the front page of your local telephone directory. The poison specialist will advise you on what to do for your child at home and whether you should take him or her to hospital. Be ready to supply the doctor or poison control centre with the following information, if known:
- Your child's age and weight.
- The name of the product ingested, its ingredients and strengths, and whether it had been prescribed for the child.
- When and how much of the product was swallowed.
- Any symptoms the child may be having.
How can iron poisoning be prevented?You can help prevent iron poisoning by taking the following precautions:
- Keep iron-containing products (and all medications) out of reach of children.
- Teach your children that pills are not sweets and can be dangerous.
- Always re-close child-resistant packaging properly. Keep in mind that childproof lids do not always guarantee safety.
- Keep ipecac solution in the home in case of poisoning.
Reviewed by Prof. Don du Toit, Faculty of Health Sciences, University of Stellenbosch.