You took the iron pills for 10 weeks, you went back for the blood draw, and your ferritin came back at 19 when it started at 11. That kind of result frustrates people, and most of the time the pills aren’t the problem. When ferritin won’t climb on iron tablets, it usually comes down to how the pill is being taken, a gut that can’t absorb it, or iron being lost about as fast as it goes in. So the way to raise ferritin is to find out which one of those you are dealing with, and only then think about a stronger pill or an IV.
Start with the easy one, because it costs nothing to fix.
Taking The Pill With Coffee Or Tums Cancels A Lot Of It
Most people take their iron with breakfast since that’s when they remember it. Breakfast is also where the coffee, the tea and the yogurt are. An old study out of Switzerland measured this with labeled iron and found black tea drunk with a meal cut the iron absorbed from it by 79 to 94%, and coffee wasn’t far behind. Milk in the cup made no real difference, so a latte or a milky chai blocks it about the same as black coffee does.
Wait an hour, and much of that effect goes away. A later trial in the UK tested tea an hour after an iron meal and found a good share of the iron got through again. That trial looked at iron from food and not from a pill, but there’s no good reason to think the pill behaves differently.
These are the usual blockers to keep a couple of hours away from your iron:
- Coffee and tea, and herbal teas too, since peppermint tea blocked iron almost as much as black tea did.
- Milk, yogurt, cheese and calcium supplements.
- Tums and other antacids, which are calcium carbonate, so they hit iron twice.
- Acid reducers like Prilosec or Pepcid, which you should not stop on your own but should bring up with whoever prescribed them.
- Thyroid medicine and some antibiotics, where it’s the iron getting in the way of the other drug.
Orange juice works the other way. Vitamin C helps the gut pull in the kind of iron found in pills, beans and spinach, and the iron in red meat, chicken and fish gets absorbed by a separate route that doesn’t care much about your coffee. Food can keep your stores up once they are full. Getting a ferritin of 11 up to a healthy number with diet alone would take a very long time, though, which is why your doctor gave you pills.
Every Other Day Absorbs Better, But It Doesn’t Fill You Up Faster
Your liver makes a hormone called hepcidin, and its job is to decide how much iron your gut lets in. A big iron pill sends hepcidin up for about a day, peaking around 8 hours later and settling by 48 hours, and while it is up the gut lets less iron through. So if you take a pill every morning, yesterday’s pill has already half shut the door on today’s.
Short absorption studies found an iron dose taken every other day got absorbed something like 35 to 50% better than the same dose taken the day after another one. That got plenty of attention online, and plenty of people switched to every other day thinking it would fix things faster.
It doesn’t, or at least not in the trial that ran it properly. A group of researchers in Switzerland gave iron depleted women the same total amount of iron either every day for 3 months or every other day for 6 months. Both groups ended up at a median ferritin of about 44. The every other day group absorbed more from each pill, sure, but they were taking half as many pills a week, and they needed double the time to land in the same spot.
Run the numbers on a standard ferrous sulfate 325 mg pill, which has 65 mg of actual iron in it:
- Daily for 12 weeks is 84 pills, or 5,460 mg of iron.
- Every other day for 12 weeks is 42 pills, or 2,730 mg.
Even if each of those 42 pills were absorbed a third better, you’d still be well behind.
Where every other day dosing did win was the stomach. Fewer women had nausea, cramps or constipation on it. A lot of people with stalled ferritin turn out to have been skipping pills on the days their stomach hurt. A schedule you can stick to will raise ferritin faster than a daily one you keep missing. Splitting the pill into 2 smaller doses a day didn’t help in the studies, by the way, since the second dose ran into the hepcidin the first one had already raised.
A Ferritin Of 19 Counts As Low Now
For years many labs printed the bottom of the normal range at around 12 or 15 ng/mL, so a 19 or a 24 came back with no flag. In September the American Society of Hematology put out its first guideline on diagnosing iron deficiency, and it raised the line. For most adults, including people who menstruate and people who are pregnant, a ferritin of 30 ng/mL or lower now counts as iron deficiency, and for people with heavy periods or ongoing symptoms doctors can use 50 or lower.
So that 11 to 19 result from the start of this page? It moved. It still sits well inside deficient territory.
Ferritin also goes up with inflammation whether you have iron or not, so somebody with active Crohn’s or a bad infection can show a 70 and still be running on empty. For those people the guideline suggests reading ferritin under 100, or a transferrin saturation under 20%, as possible deficiency, and that’s the reason a good doctor orders both tests together.
Tests To Ask For When The Number Won’t Move
If you have cleaned up the timing, you’re taking the pills on schedule, and your ferritin still barely budges after a fair try, then the gut is the next place to look. A well known paper from two hematologists, Hershko and Camaschella, followed people whose low iron either had no clear cause or didn’t respond to pills. Pills failed in every patient with celiac disease, in roughly 7 out of 10 with autoimmune gastritis or H. pylori, and in only about 1 in 10 where nothing turned up.
H. Pylori Infection
This is a stomach bug that millions of Americans carry without knowing it. It inflames the stomach lining and cuts down the acid iron needs. In that same paper, once other causes had been ruled out, clearing the infection cured somewhere between 64 and 75% of the people with stubborn, unexplained low iron. A breath test or a stool test will tell you.
Celiac Disease
Most iron gets absorbed in the very first part of the small intestine, which happens to be exactly the part celiac disease damages. Plenty of adults with celiac don’t have the classic stomach trouble at all, and stuck iron can be the only sign. The first test is a blood test called tTG, and you need to still be eating gluten when they draw it, or it can come back normal when it isn’t.
Autoimmune Gastritis
Here your own immune system goes after the cells that make stomach acid. Less acid means less iron absorbed, and it often drags B12 down with it, so if your report shows low ferritin and low B12 side by side, point that out. It’s checked with antibody tests and a gastrin level.
Heavy Periods And Slow Bleeding
For anyone who menstruates, heavy periods are the most common reason ferritin won’t hold. Soaking a pad or tampon every hour or two, passing big clots, or bleeding longer than 7 days can pull out more iron each month than a pill puts back, and the ASH guideline tells doctors to treat the bleeding itself rather than keep refilling the tank. A gynecologist visit belongs on the list. For men and for women past menopause, low iron with no clear reason gets treated as possible bleeding in the gut until proven otherwise, which is why a colonoscopy or an upper scope often follows. Daily Advil or aspirin can cause slow bleeding from the stomach too, and so can donating blood every few months.
When IV Iron Makes Sense
Hemoglobin should come up first, roughly 2 g/dL over 3 to 4 weeks if you’re anemic, and ferritin trails behind because your body rebuilds blood before it saves any extra. That’s why most doctors keep people on pills for around 3 months after hemoglobin is back to normal. If hemoglobin hasn’t moved by about 4 weeks, though, sitting on the same pills for another 3 months probably won’t change much.
IV iron goes straight into the blood, skipping the gut and the hepcidin problem altogether. Doctors turn to it when pills can’t be tolerated, when they’ve been given a real chance and failed, or when iron is needed fast, like late in pregnancy or before surgery. It won’t fix whatever caused the low iron in the first place, so the bleeding or the gut issue still has to be worked out alongside it.
Before your next blood draw, write down what time you take the pill, what you drink with it, every medicine and antacid you use, and how heavy your periods run. Take that list in, and ask for ferritin and transferrin saturation together, not ferritin alone.
This article is general information and not personal medical advice. Your own results, history and doctor should guide your treatment.
