What you take for anemia depends on what’s causing it. Iron deficiency is by far the most common type, and most people start with an oral iron supplement like ferrous sulfate. But anemia can also result from low vitamin B12, low folate, chronic kidney disease, or other underlying conditions, each requiring a different approach. Here’s what works for each type and how to get the most out of treatment.
Iron Supplements for Iron Deficiency Anemia
Iron deficiency anemia is treated with iron supplements, and ferrous sulfate is the most widely recommended because it’s effective and inexpensive. It comes in 300 mg tablets that contain about 60 mg of elemental iron, which is the amount your body can actually use. Two other common options are ferrous gluconate (35 mg of elemental iron per 300 mg tablet) and ferrous fumarate (100 mg of elemental iron per 300 mg tablet). The numbers on the bottle can be confusing because the total milligrams listed are always higher than the actual iron content inside.
Current guidelines from the American Gastroenterological Association recommend taking oral iron once a day at most. Every-other-day dosing may actually work just as well for absorption and tends to cause fewer side effects. Pairing your iron supplement with vitamin C significantly improves how much iron your body absorbs. Vitamin C converts iron into a form that intestinal cells can take up more easily, so swallowing your tablet with a glass of orange juice or a vitamin C supplement makes a real difference.
What Blocks Iron Absorption
Iron is best absorbed on an empty stomach, but several common foods and supplements interfere with absorption even when you time things well. Calcium is one of the strongest inhibitors and is unique because it blocks both plant-based and animal-based forms of iron. If you take a calcium supplement, separate it from your iron by at least a couple of hours.
Phytates, found naturally in whole grains, beans, and nuts, bind to iron in your digestive tract and reduce how much gets absorbed. Polyphenols in tea, coffee, and red wine do the same thing. On the other hand, meat proteins from beef, chicken, fish, pork, and lamb actually enhance iron absorption when eaten alongside iron-rich foods. Egg protein, interestingly, has the opposite effect and can inhibit absorption.
Dealing With Side Effects
Stomach cramps, nausea, constipation, and diarrhea are the most common complaints with oral iron. These side effects drive a lot of people to stop taking their supplements too early, which stalls recovery. A few strategies help. Taking iron with a small amount of food reduces nausea and cramping, though it slightly decreases absorption. If nausea hits at higher doses, splitting into smaller amounts throughout the day or switching to every-other-day dosing often helps. For constipation, a stool softener can keep things moving without interfering with the iron itself.
If one formulation bothers you, switching to a different iron salt (say, from ferrous sulfate to ferrous gluconate) sometimes makes a noticeable difference. The key is not to just stop. Talk to your provider about alternatives rather than quitting treatment.
When You Need IV Iron Instead
Oral iron works for most people, but some situations call for intravenous iron. If your levels are severely low, if you have bleeding in your gastrointestinal tract that’s causing rapid blood loss, or if you simply can’t tolerate oral iron after trying different formulations, IV iron delivers a large dose directly into your bloodstream and bypasses the gut entirely. People with inflammatory bowel disease or those who’ve had gastric surgery often fall into this category because their intestines can’t absorb oral iron effectively.
How Long Recovery Takes
Iron supplementation isn’t a quick fix. You can expect your hemoglobin to rise by about 2 g/dL within the first three to four weeks, which is usually when you’ll start feeling less fatigued. Over three to six months, the improvement typically reaches around 2.4 g/dL, and beyond six months, gains can reach 3.2 g/dL or more.
Your provider will usually check your levels six to eight weeks after you start treatment, then every three to six months after that. Even once your hemoglobin returns to normal, you’ll need to keep taking iron for several more months to rebuild your body’s stored reserves. Stopping too soon is one of the most common reasons anemia comes back. The total course of treatment often lasts six months or longer.
Iron-Rich Foods That Support Treatment
Supplements do the heavy lifting, but diet matters too. The iron in food comes in two forms: heme iron from animal sources and non-heme iron from plants. Your body absorbs heme iron significantly better. The richest heme sources include oysters, clams, mussels, beef and chicken liver, sardines, beef, and poultry. For non-heme iron, fortified breakfast cereals, lentils, beans, spinach, dark chocolate (at least 45% cacao), potatoes with the skin on, nuts, and seeds are all solid choices.
Eating non-heme iron alongside vitamin C or a portion of meat boosts absorption considerably. A spinach salad with lemon juice and grilled chicken, for example, delivers iron in a much more absorbable package than spinach alone.
Vitamin B12 Deficiency Anemia
Not all anemia comes from low iron. Vitamin B12 deficiency causes a type called megaloblastic anemia, where your body produces abnormally large, dysfunctional red blood cells. This is common in vegans and vegetarians, people over 60 whose stomachs absorb less B12, and those with autoimmune conditions affecting the gut.
Mild deficiency in people who simply aren’t getting enough from their diet can be corrected with oral B12 supplements. Research in vegans and vegetarians with marginal deficiency found that either a daily sublingual dose of 50 micrograms or a single weekly oral dose of 2,000 micrograms was enough to restore adequate levels. More severe deficiency, especially when neurological symptoms like numbness or tingling are present, requires B12 injections rather than oral supplements. In those cases, treatment typically starts with daily injections for two weeks, then weekly until blood counts normalize, then monthly for life.
Folate Deficiency Anemia
Folate (vitamin B9) deficiency produces the same type of megaloblastic anemia as B12 deficiency. It’s treated with oral folic acid supplements. Folate deficiency is less common now in countries that fortify grain products, but it still occurs in people with poor diets, heavy alcohol use, or conditions that impair nutrient absorption like celiac disease. One important caution: folate supplements can mask B12 deficiency by improving blood counts while the underlying nerve damage from B12 deficiency continues unchecked. Both levels should be tested before starting treatment.
Anemia From Chronic Disease
Chronic kidney disease, certain cancers, HIV treatment, and chemotherapy can all cause anemia by suppressing your bone marrow’s ability to produce red blood cells. Iron supplements alone won’t fix this type. Instead, treatment may involve medications that mimic erythropoietin, a protein your kidneys naturally produce to signal your bone marrow to make red blood cells. These medications stimulate red blood cell production directly and are given by injection, typically in a clinic setting. They’re reserved for specific situations because they carry risks, and the decision to use them involves weighing benefits against those risks on a case-by-case basis.
How Anemia Is Diagnosed
Before starting any treatment, a blood test confirms both the presence and cause of anemia. For iron deficiency specifically, ferritin (a protein that stores iron) is the key marker. The World Health Organization sets the diagnostic threshold at below 15 micrograms per liter for women and below 12 for young children. However, recent multinational research suggests hemoglobin levels actually start declining at ferritin levels around 25 micrograms per liter, and the body begins ramping up iron absorption at ferritin levels of 40 to 50, well above the traditional cutoff. This means some people with “normal” ferritin on paper may already be iron depleted.
A complete blood count, ferritin, B12, and folate levels together paint the full picture. The results determine whether you need iron, B12, folate, or an entirely different approach, which is why treatment should always start with a proper diagnosis rather than guessing.