Iron deficiency anemia is treated by restoring your body’s iron levels through supplements, dietary changes, and addressing whatever caused the deficiency in the first place. Most people start with oral iron supplements at 150 to 200 mg of elemental iron per day, though newer evidence suggests you may absorb iron more efficiently by taking it every other day instead of daily.
Find the Underlying Cause First
Iron supplements will raise your levels, but they won’t fix the problem if something is draining your iron faster than you can replace it. Iron deficiency almost always comes down to one of three things: blood loss, poor absorption, or not getting enough iron from food.
Blood loss is the most common culprit, especially in older adults where it may signal slow, hidden bleeding in the digestive tract from ulcers, polyps, or other conditions. In women of childbearing age, heavy menstrual periods account for roughly 10% of iron deficiency cases in the United States. Pregnancy increases iron demand significantly. Among young children aged 12 to 36 months, about 9% are iron deficient, with a third of those developing anemia.
Absorption problems are another major factor. Celiac disease, prior stomach surgery, and conditions that reduce stomach acid all interfere with your gut’s ability to pull iron from food or supplements. People on strict vegetarian or vegan diets and frequent blood donors are also at higher risk simply because their intake or losses don’t keep up with demand. If your iron keeps dropping despite supplementation, an absorption issue or ongoing blood loss is likely and needs investigation.
How Oral Iron Supplements Work
Oral iron is the standard first-line treatment. Your doctor will typically prescribe 150 to 200 mg per day of elemental iron, which works out to roughly 2 to 5 mg per kilogram of body weight. The “elemental iron” number is what matters, not the total weight of the tablet, since different iron formulations contain different percentages of actual absorbable iron.
Here’s something that may change how you take your supplements: when you swallow an iron dose, your liver releases a hormone called hepcidin that stays elevated for about 24 hours. While hepcidin is high, it blocks your gut from absorbing more iron. This means a second dose taken the same day gets absorbed poorly. Alternate-day dosing, where you take iron every other day instead of daily, lets hepcidin drop back down between doses and improves how much iron your body actually takes in. A pooled analysis of multiple trials found that daily and alternate-day dosing produce comparable increases in hemoglobin, with alternate-day dosing causing fewer side effects and better adherence.
Managing Side Effects
Up to half of people prescribed oral iron stop taking it because of gastrointestinal problems. The most common complaints are changes in bowel habits (about 35% of people who quit cite this), followed by nausea, vomiting, stomach pain, and diarrhea. Darker stools are normal and harmless.
Switching to an alternate-day schedule is one of the most effective strategies for tolerability. In 10 out of 11 trials that tracked side effects, daily dosing caused more gastrointestinal symptoms than non-daily dosing. Taking iron on an empty stomach improves absorption but worsens nausea for some people. If that’s you, taking it with a small amount of food is a reasonable tradeoff, though avoid the specific foods that block absorption (more on that below). Starting at a lower dose and gradually increasing can also help your gut adjust.
What Helps and Hurts Absorption
Not all iron is absorbed equally, and what you eat or drink alongside your supplement makes a real difference.
Vitamin C is the single best absorption booster. In one study, increasing vitamin C from 25 mg to 1,000 mg raised iron absorption from 0.8% to 7.1%, nearly a ninefold improvement. A glass of orange juice or a vitamin C tablet taken with your iron supplement is a simple, proven strategy. Vitamin C can also partially counteract the effects of absorption blockers.
Several common substances significantly reduce how much iron you absorb:
- Tea and coffee: The polyphenols in black tea can reduce iron absorption by 56 to 85%, depending on the study. Coffee has a similar effect. Separate these from your iron dose by at least one to two hours.
- Calcium: Dairy products, calcium supplements, and antacids interfere with iron uptake. Don’t take them at the same time as your iron.
- Phytates: Found in whole grains, bran, beans, and nuts. The inhibitory effect is dose-dependent, meaning small amounts matter less, but a bran-heavy breakfast with your iron pill is a bad combination.
The practical takeaway: take your iron supplement with vitamin C on a relatively empty stomach, away from meals heavy in dairy, grains, or tea. If you’re dosing every other day, pick a consistent time, ideally morning, when absorption tends to be best.
When IV Iron Makes More Sense
Intravenous iron bypasses the gut entirely, delivering iron straight into your bloodstream. It’s typically reserved for specific situations: when you can’t tolerate oral iron, when you have an absorption disorder like celiac disease, when your iron needs to come up quickly (such as during pregnancy or before surgery), or when your losses are too high for oral supplements to keep pace.
In patient surveys, 82% of those who received IV iron said the infusion was easier than daily pills. Side effects were substantially lower with IV iron compared to oral: nausea occurred in 1.6% versus 4.9%, vomiting in 1% versus 6.8%, and stomach discomfort in 1.3% versus 7.9%. About 28% of people who preferred IV iron said they simply couldn’t swallow tablets, and over half reported difficulty remembering to take daily pills.
IV iron is also more effective than blood transfusions for replenishing hemoglobin and iron stores, and it’s considered safer and more cost-effective than transfusion. Still, oral iron remains the recommended starting point for most people because of its lower cost and accessibility.
Iron-Rich Foods to Add to Your Diet
Dietary iron comes in two forms. Heme iron, found in animal products, is absorbed at about 25%. Non-heme iron, found in plants, is absorbed at 17% or less. That difference matters when you’re trying to rebuild depleted stores.
The richest sources of heme iron are red meat, dark poultry meat (thighs and drumsticks over breast meat), fish, and shellfish. These are the most efficient food sources for raising iron levels. Eggs are an exception among animal foods: they contain only non-heme iron.
Good plant-based sources of non-heme iron include legumes, dark leafy greens like spinach, nuts, seeds, whole grains, dried fruits, and dark chocolate. Pairing these with vitamin C-rich foods (bell peppers, citrus, tomatoes, strawberries) at the same meal meaningfully improves how much iron you absorb. Cooking in cast iron cookware also adds small amounts of iron to food, particularly with acidic dishes like tomato sauce.
Diet alone is rarely enough to correct established anemia, but it plays an important supporting role during treatment and helps prevent recurrence once your stores are replenished.
How Long Treatment Takes
Iron supplementation works faster than most people expect for hemoglobin recovery. In a randomized trial, people taking iron supplements recovered their hemoglobin levels in roughly 31 to 36 days on average, compared to months without supplementation. Women tended to take slightly longer (32 to 36 days) than men (25 to 30 days).
But here’s the part many people miss: normalizing your hemoglobin is only half the job. Your body also needs to refill its deeper iron reserves, measured by a blood protein called ferritin. After your hemoglobin returns to normal, you should continue iron therapy for an additional four to six months to fully restock those reserves. Your ferritin should be rechecked three to six months after your hemoglobin normalizes, with a target above 100 micrograms per liter.
Stopping too early is one of the most common reasons iron deficiency comes back. Once your stores are fully replenished and any underlying cause is addressed, people with ongoing risk factors (heavy periods, vegetarian diets, regular blood donation, growth spurts in adolescents) may benefit from a lower maintenance dose to prevent recurrence.
Knowing If Treatment Is Working
The current diagnostic threshold for iron deficiency is a ferritin level below 15 micrograms per liter for women and below 12 for young children, based on WHO guidelines. However, a 2025 multinational study found that hemoglobin levels actually start declining when ferritin drops below about 25 micrograms per liter for women and 22 for children, suggesting that functional iron deficiency begins well before it meets the traditional cutoff.
During treatment, your energy and symptoms often improve within a few weeks as hemoglobin rises. If you’re not seeing improvement after four to six weeks of consistent supplementation, that’s a signal something else may be going on: poor absorption, continued blood loss, or a different type of anemia altogether. Blood work at that point can clarify whether your ferritin and hemoglobin are trending in the right direction or whether a different approach is needed.