Preparing for an iron infusion

Eat a light meal and drink plenty of water before an iron infusion, and stop any iron tablets the day before. Tell us if you are pregnant, have allergies or asthma, or feel unwell. The iron runs through a drip over 15 to 30 minutes, and you stay with us for 30 minutes afterwards.

Before your appointment

You will have a consultation before your infusion, often by video call, to talk through any worries so you know what to expect.

Tell us at the consultation if any of these apply to you:

• You are pregnant, or could be. Intravenous (IV) iron is not given in the first three months of pregnancy, when iron tablets are the usual treatment.
• You have had a reaction to an iron injection or infusion before.
• You have allergies, including to medicines, or a history of severe asthma or eczema.
• You have an immune or inflammatory condition, such as rheumatoid arthritis or lupus.
• You have liver disease, or have been told your iron levels are high.

This lets the team plan your infusion safely. The Iron Clinic has specific protocols for people with allergies or a past reaction to iron.

The day before

Stop taking iron tablets the day before your appointment. Keep taking your other medicines as usual unless we have told you otherwise. INSERT: Toby to confirm advice on other medicines

If you develop a cold, flu, COVID or any other infection, call us before you come in. We may move your appointment until you feel better.

On the day

You do not need to fast. Eat a light meal before you come, and drink plenty of water. Being well hydrated makes it easier to find a vein and place the small needle, called a cannula, that the iron runs through.

INSERT: total appointment time, and whether patients can drive home afterwards

What happens during the infusion

The team will check your pulse and blood pressure. A nurse places the cannula in a vein in your hand or arm, then flushes it with salt water to check it is sitting well inside the vein.

The iron is a dark brown liquid mixed into a small bag of salt water, about 100 ml, and given as a drip over 15 to 30 minutes. For smaller doses it is sometimes given as a slow injection over a few minutes instead. We start slowly and watch you closely, especially in the first few minutes, and repeat your pulse and blood pressure as it runs.

Tell the nurse straight away if you feel flushed, dizzy, itchy, short of breath or tight in the chest, during the infusion or afterwards. These reactions are uncommon, and most settle within a minute once the drip is stopped.

Tell the nurse straight away if the area around the cannula stings, hurts or swells. If the iron leaks out of the vein it can leave a brown stain on the skin that can be permanent, so we take great care with the cannula and may move it to another vein.

After the infusion

Once the drip has finished, we check you are well and repeat your observations. We then ask you to wait for 30 minutes before you go home, so the team can watch for any reaction.

INSERT: Toby to confirm when the cannula comes out, before or after the 30-minute wait

About 1 in 4 people feel flu-like about a day after the infusion, with aches and a mild temperature. It usually settles on its own within a day or two, and occasionally lasts up to a week. Drink plenty of fluids and take ordinary painkillers from the pharmacy if you need them.

Many people notice a difference within days, with restless legs and the urge to eat ice going first. The full benefit is usually felt by 6 to 8 weeks. Book a follow-up blood test for 2 to 3 months after your infusion.

Frequently asked questions

Do I need to fast before an iron infusion? No. Eat a light meal and drink plenty of water before you come.

Should I take an antihistamine first? Not routinely, because medicines given to prevent a reaction can cause side effects of their own. We may suggest one if you are prone to hives.

Can I have an iron infusion if I am pregnant? Not in the first three months. Later in pregnancy it can be given when the benefits clearly outweigh the risks, and we will discuss this with you.

INSERT: Toby to confirm the clinic treats in the second and third trimesters

If you have questions before your infusion, contact The Iron Clinic.

Sources

1. The Iron Clinic. Patient information sheet for intravenous (IV) iron therapy, version 1.5, 7 January 2025. theironclinic.com.
2. Medicines and Healthcare products Regulatory Agency (MHRA). Intravenous iron and serious hypersensitivity reactions: strengthened recommendations. Drug Safety Update 2013;7(1):A1. gov.uk, read 14 October 2026.
3. Summary of Product Characteristics for ferric carboxymaltose and for ferric derisomaltose. Electronic medicines compendium, medicines.org.uk, read 14 October 2026.
4. Richards T, et al. Questions and answers on iron deficiency treatment selection and the use of intravenous iron in routine clinical practice. Annals of Medicine 2021;53(1):274-285. doi:10.1080/07853890.2020.1867323