Having an Iron Infusion
A drip that tops up your iron stores in one or two visits, for when tablets haven’t worked, can’t be taken, or iron is needed quickly. Usually quick and well tolerated, with two side effects worth knowing about before you start: skin staining and low phosphate.
Your iron infusion, step by step
From deciding to have one to the check-up blood test. Most people sail through; knowing what to watch for keeps it that way. For causes of low iron and tablet tips, see our iron deficiency sheet.
- Step 1 · BeforeCheck whether tablets could do the jobIron tablets every second day work for most people. Infusions are for when tablets fail or aren’t tolerated, with poor absorption (such as bowel disease or after weight-loss surgery), in later pregnancy, before surgery, or when iron is needed fast.
- Works
- About 7 in 10 people respond to tablets within 2 weeks; an infusion refills stores in one or two visits
- Cost
- Tablets about $10–20 a month
- How long
- Tablets: at least 3 months
- Watch for
- An infusion only helps if you’re actually low in iron. It won’t fix tiredness from other causes
Faster isn’t fancier. If tablets work for you, they win.
- Step 2 · PreparationBlood tests and the right questionsYour doctor confirms iron deficiency and may check phosphate. Tell them about asthma, eczema or allergies, any past reaction to iron, pregnancy, infections or liver problems.
- What happens
- You’ll be asked to consent, including to the small risk of permanent skin staining. Ask which iron you’re having: it changes how long it takes and the phosphate risk
- Cost
- The iron is $25 on the PBS ($7.70 concession); clinic fees range from bulk-billed to a few hundred dollars
- How long
- One appointment
- Watch for
- Infusions aren’t given in the first 3 months of pregnancy
Good questions now save a lot of “I wish I’d known” later.
- Step 3 · On the dayThe infusionEat and drink normally, take your usual medicines, drink water (it makes veins easier to find), skip iron tablets that day, and wear loose sleeves. A nurse places a small tube (cannula) in a vein and checks your blood pressure and pulse.
- What happens
- The drip takes about 15 minutes for ferric carboxymaltose or 20–30 minutes for ferric derisomaltose, longer for older types; then you’re watched for about 30 minutes
- Cost
- As above
- How long
- About 1 hour all up for most people
- Watch for
- Keep your arm still. Tell the nurse straight away about any stinging, burning, swelling or pain at the drip site, or rash, itch, tight chest or throat, or dizziness
Speak up early. “It stings a bit” is exactly what the nurse needs to hear.
- Step 4 · First few daysMild side effects and restHeadache, flushing, muscle or joint aches, nausea or a metallic taste are common and usually settle within a couple of days. Darker urine the next day is normal.
- What happens
- Paracetamol and rest usually help. Most people can drive home, unless they feel unwell
- Cost
- Free
- How long
- 1–2 days
- Watch for
- Don’t restart iron tablets unless your doctor says to, and usually not for at least a week
A couple of meh days for months of better iron.
- Step 5 · 2–4 weeks laterCheck-up blood testA repeat blood test shows whether your iron has risen enough or you need a second dose.
- What happens
- Tiredness and breathlessness often ease within about 2 weeks; the full benefit can take 4 weeks
- Cost
- Bulk-billed blood tests are free for many people
- How long
- One test, then usually another a few months later
- Watch for
- Still finding the cause. Heavy periods or hidden gut bleeding will empty your stores again
Refilling the bucket is step one. Fixing the leak is step two.
- Step 6 · If you need repeat infusionsPhosphate checksSome iron types, especially ferric carboxymaltose, can lower phosphate, a mineral your muscles and bones need. The risk rises with repeat or high doses.
- Works
- In a 2022 trial in people with bowel disease, low phosphate occurred in about half given ferric carboxymaltose and fewer than 1 in 10 given ferric derisomaltose
- Cost
- A blood test, often bulk-billed
- How long
- Before repeat doses, and if symptoms appear
- Watch for
- Higher risk with vitamin D deficiency, bowel disease or osteoporosis. Rarely, long-lasting low phosphate softens bones and causes fractures
One infusion is usually simple. Repeats need a little more care.
Skip these
Common requests and add-ons that don’t help, or add risk without benefit.
- Infusions for tiredness when your iron is normalExtra iron doesn’t boost energy if you’re not low, and every dose carries some risk.
- Vitamin “drips” added onNo good evidence they help, and they add cost. The iron is the bit that works.
- Repeat infusions on a schedule without a blood testEach dose adds phosphate risk. Let a blood test decide.
- Skipping the causeAn infusion is a refill, not a diagnosis. Without fixing the cause, you’ll be back.
What you can do
- Keep a note of the date, the type of iron and the dose. It helps if you ever need another.
- Book your follow-up blood test before you leave.
- If a brown mark appears at the drip site, take photos and tell the clinic and your GP.
- Report new muscle weakness, bone or joint pain, or worse tiredness in the weeks after, especially after repeat infusions.
- Keep working on the cause with your GP: heavy periods, diet, coeliac disease or gut bleeding.
See your GP if
- You’re still tired or breathless 4 weeks after your infusion
- You have new muscle weakness, muscle or bone pain, or tiredness that’s getting worse (possible low phosphate)
- There’s brown discolouration, pain or swelling where the drip was
- Headache, aches or fever last more than a few days
Tell staff immediately during the infusion if you feel unwell, itchy, flushed, dizzy, or have a tight chest or throat. Serious allergic reactions are rare, and staff are trained to treat them. After you leave, call 000 (or your local emergency number) for swelling of the lips or tongue, trouble breathing, chest pain or collapse.
Common questions
How long does an iron infusion take?
Usually about an hour all up. The drip itself takes about 15 minutes for ferric carboxymaltose and 20–30 minutes for ferric derisomaltose (older types take hours), plus about 30 minutes of observation afterwards.
Does an iron infusion hurt?
Usually just a sharp scratch when the cannula goes in. Stinging, burning or swelling during the drip isn’t normal: tell the nurse straight away.
Can an iron infusion stain my skin?
Uncommonly, iron leaks from the vein into the skin and leaves a brown stain that can be long-lasting or permanent. Keeping your arm still and reporting any stinging or swelling at once lowers the risk, because the drip can be stopped.
What is low phosphate after an iron infusion?
Some iron types, mainly ferric carboxymaltose, make the body lose phosphate through the kidneys. It often causes no symptoms, but can cause tiredness, muscle weakness and bone pain, and rarely bone softening and fractures. It’s more likely after repeat or high doses, so phosphate may be checked before repeats.
Can I have an iron infusion while pregnant?
Not in the first 3 months. In the second and third trimesters, infusions are considered safe when tablets aren’t enough or time is short.
How soon will I feel better?
Many people feel better within about 2 weeks, with the full benefit by about 4 weeks. Your haemoglobin is usually rechecked 2–4 weeks after the infusion.
Helpful resources
- Iron deficiency fact sheetCauses, tablet tips and when an infusion makes sense. Free, from us.
- Iron infusion dose calculatorThe dosing tool clinicians use, if you’re curious how your dose was worked out. Free, from us.
- Healthify: Iron infusionClear patient guide from a New Zealand health site, including low phosphate symptoms. Free.
- The Royal Women’s Hospital: Iron infusionsPatient fact sheet covering pregnancy, preparation and aftercare. Free, Australia.
Evidence and more information
- The Royal Women’s Hospital (Victoria): Iron infusions fact sheet
- Healthify He Puna Waiora: Iron infusion
- Gloucestershire Hospitals NHS: Having an iron infusion
- Avant: Iron staining, understanding the risks
- MHRA: Ferric carboxymaltose and low phosphate
- FDA (2026): Boxed warning for ferric carboxymaltose and low phosphate
- Gut (2022): PHOSPHARE-IBD trial, low phosphate after two iron types
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