30/03/2026
IRON INFUSION - PRO's and CON's
Iron deficiency is common, on average women suffer for 8 years and spend 2-3 years on oral iron supplements. It can be a disabling disease and really impact both mentally and physically. Oral tablets may work well but in some cause side effects or not work. The option then is an Iron Infusion which can work very well and in many, at a full treatment dose, be a 'one off treatment'. But as with any pill/tablet/treatment there can be problems, after all nothing is without risk - so what are these?
Iron Dextran, this is an old preparation used in the 1970's-1990's and much of the concern stems from this as it did cause reactions and anaphylaxis. It was reserved for kidney disease and hospital patients. It was replaced by INFED that enables a high dose of IV iron at a much lower risk profile - in the USA, as cheaper, this is a good option today.
Iron sucrose, Venofer, has been around for decades but given at a low dose over an hour, so many treatments are required (and risk is per treatment not dose)
Ferinject and Monofer are the modern preparations that are carbohydrates. They enable a treatment dose of 1000mg or more in 15-30mins. In the last 15 years they have transformed care with over 120million doses. Making IV iron available to many. But with so much more use there are always increase in knowledge of side effects.
Overall an iron infusion is a safe procedure. We encourage people not to be nervous as this should be no more concern than an injection of antibiotics. We have also found having the consultation in advance on zoom gives people the opportunity to read this patient information and discuss any concerns before coming for their infusion so they are full prepared and know what to expect.
At the start, the clinic nurse will place a drip in your arm. It’s important that this is sitting well within a vein so they will check this with a flush of cold water that you may feel going up the arm. Particular attention is spent to ensure the line runs without problems, this may include a second flush or a saline drip before the iron infusion. In some cases, we may re-site the cannula to another location. In unfortunate cases the line sometimes tissues or leaks, this can leave a brown stain or tattoo. Every attempt is made to reduces this risk as the stain can be permanent.
With the infusion there are some common side effects. It is not recommended to give pre-medications as these can cause side effects themselves.
Flushing reactions (Fishbane) can occur, and often minor (like those seen with a CT scan infection). It can develop within minutes of the infusion starting, so we start the infusion slowly and you are under close observation, the nurse may stop the infusion for several minutes and restart.
Flushing is common and we see it in about 1 in 50 cases. It can be unpleasant and you might feel a flushed, lightheaded, develop a dry cough, chest tightness feel queasy or dizzy. These can last 20-30 seconds and resolves quickly with the infusion stopping. The team may give an antihistamine medication (hay fever tablet) or sometimes a steroid injection. Normally following a period of observation they will restart and finish the infusion slowly
Hives, or a rash can develop at any stage in about 1 in 200-500 people and this why we ask people to wait for 30 minutes after their infusion. These normally settle with Piriton or an anti-histamine. If you are prone to allergy or hives we may suggest taking an anti-histamine before treatment.
Other side effects and severe reactions are rarer following treatment of iron include swelling of the hands and feet, and very rarely, anaphylactic like reactions (e.g. paleness, swollen lips, itchiness, weakness, sweating, dizziness, feeling of tightness in the chest, chest pain, fast pulse, difficulty in breathing). The team are all trained and the necessary equipment and protocols are in place.
Overall, about 3% of people who receive intravenous iron do feel some side effects, the vast majority of which are mild and self-limiting. The major risk is calculated at less than 10 people in a million. In a recent detailed review (JAMA 2016) it was suggested that the risk of the new types of IV iron (which we use) carried the same risk as many other infusions such as an antibiotic and overall, about one third the risk of receiving a blood transfusion.
AFTER THE INFUSION
It is common for many people to develop a Post Infusion Flu, this affects about 1 in 4 people. This develops about 24 hours later and can be like a bad flu with aches and pains, feeling unwell and a mild temperature. We are not sure why this occurs and termed a ‘serum sickness’. It is self-limiting and can last up to a week. It important to keep well hydrated and take normal painkillers from the chemist if required.
With some preparations of IV iron, a fall in blood levels of Phosphate (Hypophosphatemia) can occur in a third to half of patients in the weeks after an infusion. In the clinical trials to date this appears to be an incidental laboratory finding and guidance suggests not to routinely test phosphate levels. Treatment is conservative and advance supplementation to prevent does not appear to be beneficial.
In our experience over the last decade we have had 2-3 cases reported as symptomatic low phosphate and management is oral phosphate and support as it resolves over a couple of weeks. At present there are no good research on this emergent risk and we are monitoring this and documenting to assess.
Hypophosphatemia, is reported to be a problem in people requiring repeat infusions (e.g. patients with Inflammatory bowel disease requiring 5-10 infusions p.a.) so in the setting and for those requiring repeat infusions we may use other preparations.
