The Iron Problem Nobody Talks About
Iron deficiency is the most common nutritional deficiency in the world. In the UK, it's particularly prevalent in women of reproductive age, older adults, endurance athletes, and people with gastrointestinal conditions. The standard treatment is iron tablets — cheap, widely available, and effective for many patients.
But for a significant proportion of people, iron tablets simply don't work. They either cause intolerable side effects (nausea, severe constipation, abdominal cramping), are poorly absorbed due to gut conditions, or fail to raise ferritin meaningfully after months of consistent use. If you recognise this pattern, an iron infusion may be the appropriate step.
How Iron Tablets Work
Oral iron supplements — ferrous sulphate, ferrous fumarate, ferrous gluconate — work by presenting iron to the gut for absorption. In theory, iron from the tablet crosses the intestinal wall into the bloodstream and is transported to where it's needed. In practice, absorption is highly variable.
Several factors limit oral iron absorption:
- Gut conditions: Coeliac disease, Crohn's disease, ulcerative colitis, and post-bariatric surgery all compromise the absorptive surface.
- Hepcidin regulation: Your body naturally suppresses iron absorption when inflammation is present — meaning those who most need iron can be least able to absorb it.
- Food and medication interactions: Calcium, coffee, tea, and antacids all reduce absorption. Taking tablets correctly is more difficult than it sounds.
- Dose tolerance: Higher doses cause more side effects, so patients often under-dose to tolerate treatment.
Even under ideal conditions, oral iron raises ferritin slowly — typically 3–6 months to reach target levels, and only if you can tolerate the tablets throughout.
How Iron Infusions Work
An intravenous (IV) iron infusion delivers iron directly into the bloodstream, bypassing the gut entirely. There's no reliance on absorption, no digestive side effects, and no months of waiting. Modern preparations — particularly ferric carboxymaltose — allow large doses to be administered safely in a single session, with iron stores typically replenished within weeks rather than months.
The treatment itself involves a cannula inserted into a vein (usually in the forearm), through which an iron solution is administered slowly over 30–60 minutes. It is not painful beyond the initial cannula insertion. Patients typically report noticeable improvements in energy and breathlessness within 1–2 weeks of their first session.
Our Protocol: What to Expect
At Lambert Medical Practice, our standard iron infusion protocol involves:
Day 1
GP assessment + first infusion. We review your blood results, confirm suitability, and administer the first IV iron dose.
Week 2
Second infusion. The two-session protocol maximises iron delivery and helps the body absorb and utilise it effectively.
Week 6
Follow-up blood test to check ferritin, haemoglobin, and iron studies. Some patients may need further sessions based on their results.
The number of infusions needed varies by individual. Patients with very low ferritin or active blood loss (e.g. heavy periods, chronic gastrointestinal bleeding) may require additional sessions. Your GP will advise after seeing your initial results and Week 6 test.
Iron Infusion vs Tablets: Side-by-Side
| Factor | Iron Tablets | Iron Infusion |
|---|---|---|
| Absorption | Variable (10–30%), gut-dependent | 100% — bypasses the gut |
| Speed of response | 3–6 months | 1–2 weeks for energy; full repletion by week 6 |
| GI side effects | Common (nausea, constipation) | None (GI system bypassed) |
| Suitable for | Mild deficiency, good gut absorption | Moderate–severe deficiency, malabsorption, intolerance to tablets |
| Convenience | Daily tablet — easy to forget or stop | 2 clinic visits + follow-up test |
| Compliance risk | High — side effects cause many patients to stop | Low — complete with clinical support |
Who Should Consider an Iron Infusion?
An infusion is typically recommended when one or more of the following apply:
- You've tried oral iron for 3+ months without significant improvement in ferritin
- You cannot tolerate the gastrointestinal side effects of iron tablets
- You have a diagnosis of coeliac disease, IBD, or have had bariatric surgery
- Your ferritin is severely depleted (below 15–20 mcg/L) and needs rapid correction
- You're experiencing significant fatigue, breathlessness, or exercise intolerance affecting quality of life
- You're preparing for surgery and need iron stores raised quickly
Before Your Infusion: The Blood Test
Every patient at Lambert Medical Practice receives a blood test before treatment to confirm iron deficiency and establish a baseline. This typically includes Full Blood Count, ferritin, serum iron, and TIBC. Your GP reviews the results before prescribing the infusion dose — ensuring treatment is appropriate, safe, and correctly calibrated.
If you haven't had a recent iron blood test, we can arrange one at the same visit.
Book Your Iron Assessment
If you're struggling with iron deficiency and tablets haven't been the answer, book an iron assessment at Lambert Medical Practice. We'll review your blood tests, discuss whether an infusion is appropriate, and walk you through the full treatment protocol.
Learn more about our Iron Infusion service →