The 8 Best Iron Supplements of 2021, According to a Dietitian

Replete iron levels with our top picks

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Iron Supplements

Verywell / Sabrina Jiang

Our Top Picks
They are slow release, delivering iron over a longer period of time to decrease any potential gastrointestinal side effects.
Delivers 15 milligrams of iron, half as iron glycinate and half as iron aspartate, along with vitamin C.
Floradix is an easily absorbable, plant-based, liquid iron supplement containing organic iron in addition to herb extracts, fruit juices, and vitamins C and B complex.
Offers both heme and non-heme iron, which helps to enhance absorption while keeping gastrointestinal side effects at a minimum.
Offers nine mg of whole food fermented ferrous fumarate iron and powerful probiotics in the form of lactic acid bacteria, which will help prevent digestive complications.
Offer 10 milligrams of iron per a two-gummy serving—in addition to Vitamin C, Vitamin A, Folic Acid, Zinc and Vitamin B complex.
Each dose of two tablets delivers 25 milligrams of iron, plus vitamin C to promote absorption.
Highly effective in boosting iron levels without any digestive side effects.

Iron is an essential mineral our bodies need for growth and development. It is the fuel our body uses to make hemoglobin, a red blood cell protein responsible for carrying oxygen from the lungs to all parts of the body, and myoglobin, a protein that provides oxygen to muscles. Additionally, it is crucial in order to make hormones and connective tissue. 

The majority of people absorb the iron they need without a supplement. However, specific groups of people are more prone to an iron deficiency, especially those who don't get enough in their diet, like vegans and vegetarians. Teen girls and women with heavy periods, pregnant women and teens, infants (especially if they are premature or low-birthweight), frequent blood donors, and people with cancer, gastrointestinal disorders, or heart failure—are also more likely to be deficient.

Iron deficiency is one of the most common nutritional deficiencies in the world, affecting around two billion people. Without adequate iron, a person may develop iron-deficiency anemia. While short-term iron deficiency can go unnoticed—due to the fact that the body will use up iron already stored—symptoms can arise once iron is depleted from the body.

Common symptoms include extreme fatigue, pale skin, brittle nails, lightheadedness, dizziness, cold feet or hands, and shortness of breath. Heart problems such as rapid or irregular heartbeat are also possible manifestations of iron depletion. 

Before taking an iron supplement, you should find out if you are iron deficient, which can be determined via a simple blood test at your doctor’s office.

If you do establish that you are iron deficient, you should keep a few things in mind before taking the supplement. Take calcium separately, as it can interfere with the absorption of iron. Consider taking iron with vitamin C, as it can improve the absorption of iron. Also, you might experience some side effects, the most common of which is constipation.

Here are the best iron supplements:

Best Overall: Slow Fe Iron Tablets

Slow Fe Iron Tablets are doctor-recommended, highly potent iron tablets that will deliver 45 milligrams of elemental iron—equivalent to 142 milligrams of ferrous sulfate—efficiently.

One of the great things about them is that they are slow-release, delivering iron over a longer period of time to decrease any potential gastrointestinal side effects—including nausea, abdominal discomfort, or constipation. These easy-to-swallow pills are meant for daily use, are available almost everywhere, and are also budget-friendly. 

Best with Vitamin C: Pure Encapsulations Iron-C

Pure Encapsulations Iron-C-

Pure Encapsulations is a highly regarded company in the vitamin and supplement industry, offering high-quality, hypo-allergenic dietary supplements that are vegan, gluten, and GMO-free. Taking iron along with vitamin C—also known as ascorbic acid—may promote absorption.

Each of their Iron-C capsules delivers 15 milligrams of iron, half as iron glycinate and half as iron aspartate, along with vitamin C, ascorbic acid, resulting in optimal absorption. Due to the fact that it is not slow release and offers a lower dosage of iron, one to two capsules daily are recommended. 

Best Liquid: Flora Floradix Iron + Herbs Liquid

Taking iron in liquid form can be easier on the stomach. Floradix is an easily absorbable, plant-based, liquid iron supplement containing organic iron in addition to herb extracts, fruit juices, and vitamins C and B complex.

The recommended dosage is 10 milliliters twice a day, providing 15 milligrams of elemental iron. Keep in mind that if you are extremely anemic, this probably isn’t going to be enough to restore your iron levels. 

Best Tablet: Feosol Bifera Iron Caplets

Feosol Complete with Bifera is a once-a-day-and-done iron caplet offering 28 milligrams of gentle iron. Unlike other iron supplements it offers both heme and non-heme iron, which helps to enhance absorption while keeping gastrointestinal side effects at a minimum. 

Best Organic: New Chapter Iron Complex Tablets

New Chapter is a go-to brand for anyone looking for high-quality, certified organic vitamins and supplements. Their Iron Complex is a once-daily supplement offering nine milligrams of whole food fermented ferrous fumarate iron and powerful probiotics in the form of lactic acid bacteria, which will help prevent digestive complications.

In addition, there are complementary nutrients—including vitamin C, vitamin E, folate, and B12—as well as herbs like ginger, turmeric, and peppermint to support stress, energy, and digestion. 

Best Gummy: BeLive Iron Gummies

It can be difficult to get children (or even stubborn adults) to take an iron supplement. BeLive Iron Gummies are the ultimate game-changer for those who have a resistance to caplets or capsules. Not only are they delicious with their artificial color and flavor-free grape taste, but they offer 10 milligrams of iron per a two-gummy serving—in addition to vitamin C, vitamin A, folic acid, zinc, and vitamin B complex (B3, B5, B6, B12).

Bottom line is that they are an easy and efficient way to deliver the mineral in an easily digestible and delicious manner. Fans claim they are easy on the stomach and digestive system and are less likely to cause constipation.

Best Vegan: MegaFood Blood Builder Minis


MegaFood is an excellent supplement company that has been making high-quality, whole food supplements for 50 years. Their Blood Builder Mini tablets are free of gluten, dairy, soy, and GMOs, and are also certified vegan and Kosher.

Each dose of two tablets delivers 25 milligrams of iron, vitamin C to promote absorption, and folic acid and B12 for healthy red blood cell production, derived from beets, oranges, and broccoli. 

Best Budget: Amazon Elements Iron Capsules

Iron can be an especially expensive supplement—costing upwards of $30 per month. If you are looking for something a little more budget-friendly, we suggest Amazon Elements Iron, offering a six-month supply of 18 milligrams capsules of ferrous bisglycinate.

They are gluten-free and vegan and don't contain any artificial colors, flavors, or chemical preservatives. While reviewers aren’t crazy about the after taste, they maintain that these capsules are highly effective in boosting iron levels without any digestive side effects.

Final Verdict

Slow Fe Iron Tablets (view at Amazon) are the gold standard in blood building, recommended by doctors as a safe, effective, and side-effect-free method of delivering high doses of the mineral. While they aren’t quite as inexpensive as some of the other iron products on our list, they offer two to three times the amount of iron than most of them. In other words, you are getting more bang for your buck.

What to Look for in an Iron Supplement


The cost of iron varies significantly—anywhere from around $1.80 to over $25 a month. While all the various types, brands, and forms we feature are effective in delivering iron, keep in mind you are going to pay more for one that is made out of whole foods or is Certified Organic. 

Supplement Form:

Iron supplements come in many forms, such as liquid, capsules, tablets, and in some cases, intravenous iron. The most concentrated over-the-counter forms are tablets and capsules, giving you the most bang for your buck. However, if you have trouble swallowing a pill, gummies and liquid are other viable options. 

Type of Iron:

Iron supplements come in many forms, such as ferrous sulfate, ferrous bisglycinate, and ferrous glycinate. It is important to note that there is a difference between “ferrous sulfate” and “elemental iron.” For example, a supplement may contain 325 milligrams (mg) of ferrous sulfate and 65 mg of elemental iron. Fortunately, elemental iron is listed in the Supplement Facts panel, so consumers do not need to calculate the amount of iron supplied by various forms of iron supplements.

Some forms of iron are best absorbed on an empty stomach (ferrous sulfate), whereas others are better absorbed in the presence of food. The type of iron that is best for you will depend on your needs, medical history, and any gastrointestinal distress that may result from taking an iron supplement. It is important to work with your healthcare provider to find the best form for you.


Before you begin taking any iron supplement, it is crucial to figure out how much you need to take. Speak with your healthcare expert to determine a dosage that is safe but effective for you. If you are extremely anemic, you will likely want to consider products offering a higher dose of iron. 

Complementary Ingredients:

In general, it is best to keep the ingredient list as small as possible; however, when it comes to supplemental iron, often there will be added ingredients such as vitamin C, which may help absorption. Many times supplements that have additional ingredients may be more expensive than others that keep it simple by focusing only on the nutrient.

Common complementary ingredients are vitamins, minerals, probiotics, and enzymes. Consider how you can consume these other nutrients from food to save money and keep things simple. 

Frequently Asked Questions

  • Why may vegans and vegetarians require additional iron?

    Even though iron is found in various foods such as dark leafy greens and beans, this plant-based form is non-heme iron and is not typically as easily absorbed as heme, or animal-derived iron that is found in red and white meats, eggs, and seafood. Many individuals who do not consume animal products find themselves at an increased risk of iron deficiency.

  • How much iron do I need on a daily basis?

    If you are iron deficient, you should speak with your doctor to choose how much iron to supplement with, based on your bloodwork. In general, iron needs vary by person and age. Adult men require 8 milligrams per day, while women between the ages of 19 to 50, who are menstruating, require 18 milligrams per day. Once a woman hits menopause, the requirement drops to 8 milligrams per day.

    The Recommended Daily Allowance increases during pregnancy and lactation, and the RDA for vegetarians is 1.8 times higher than for people who eat meat.

    Tolerable Upper Intake Levels (UL) for iron from food and supplements based on the amounts of iron associated with gastrointestinal effects following supplemental intakes of iron have been established. The ULs apply to healthy infants, children, and adults. Physicians sometimes prescribe intakes higher than the UL, such as when people with iron deficiency anemia need higher doses to replenish their iron stores. Doses of iron supplements may need to be taken throughout the day to optimize absorption and minimize side effects. Always check with your physician before starting an iron supplement, and be sure to get a specific recommendation for the type of iron and dosage.

  • Is it dangerous to take too much iron?

    Yes, taking too much iron may cause liver disease, abdominal pain, joint pain, heart attack, and an increased risk for diabetes. High doses of iron can also decrease zinc absorption.

  • What are common side effects of iron supplementation?

    Common side effects include constipation, abdominal pain, nausea, and vomiting. You may notice a change in stool color after starting supplementation. Iron may darken stool, and this is usually nothing to be alarmed by. However, it is important to communicate any stool color changes to your doctor, as darker stools may also indicate intestinal bleeding.

  • What form of iron is best to take during pregnancy?

    If your doctor has recommended iron supplementation while you are expecting, be sure to consider form, dosage, and side effects when purchasing. A slow-release tablet may be better tolerated and help avoid common pregnancy complaints such as constipation and nausea.

    Note that your prenatal likely has iron in it, so consider that amount when looking at additional supplementation.

  • Why should you avoid taking antacids at the same time as iron supplements?

    Antacids contain calcium, which can interfere with iron absorption. Also, avoid drinking milk or taking calcium at the same time as your iron supplement.

  • What is the difference between heme and non-heme iron?

    Plants such as nuts, beans, and vegetables, as well as iron-fortified foods like some cereals, bread, and other grains contain non-heme iron only, whereas meat, seafood, and poultry contain both heme and nonheme iron. Heme iron has higher bioavailability than nonheme iron, meaning humans can better absorb and utilize heme iron

  • Do iron supplements interact with medication?

    Iron can interact with certain medications, and some medications can have an adverse effect on iron levels. Gastric acid is an important component of the absorption of iron. For this reason, individuals taking proton pump inhibitors (PPIs) may have a suboptimal response to iron supplementation. The simultaneous ingestion of iron and Levothyroxine (Levothroid, Levoxyl, Synthroid, Tirosint, and Unithroid)—a medication used to treat hypothyroidism, goiter, and thyroid cancer— can result in clinically significant reductions in levothyroxine efficacy in some patients.

    For more information on medications that might interfere with or be interfered with by iron supplementation, consult your doctor or visit the NIH Office of Dietary Supplements website

What Experts Say

"For those who experience constipation during supplementation, I recommend focusing on good hydration and fiber intake. Aim for at least 2 liters of water daily. Fiber recommendations for the average adult range from approximately 25 to 35 grams per day.  When increasing fiber in your diet, make sure to go gradually and ensure that you are spreading it out throughout the day for optimal tolerance." — Arielle Leben, RD

Why Trust Verywell Health?

A personal note on my recommendations written above. As a dietitian, I am careful to recommend supplements, including iron. I spent time reviewing the most current recommendations on iron supplementation, and I looked at multiple brands and products. I believe the supplements in the round-up are made by trusted brands that are devoted to product purity and are composed of high-quality ingredients. — Eliza Savage, MS, RD, CDN

Sydney Greene, MS, RD contributed to FAQs and key buying information for iron supplements.

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Article Sources
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