Thorne Iron Bisglycinate Capsules is our pick for the best iron supplement. But there are many others that may work for you. See our dietitian’s top choices.

Your body depends on iron for vital processes, such as oxygen transportation, hormone production, growth, and neurological development.

Most people can get all the iron they need by eating a nutrient-dense, well-rounded diet. But if you have inadequate iron intake, increased need, or impaired absorption, you may be at risk of low iron levels and iron deficiency anemia.

If a healthcare professional recommends supplemental iron, you might consider the following options vetted by Healthline’s medical and nutrition experts.

Pricing guide

  • $ = under $0.20 per serving
  • $$ = $0.20 to $0.40 per serving
  • $$$ = over $0.40 per serving

ProductPriceRecommended dose% of DVType of ironThird-party tested
$$1 capsule139%ferrochel ferrous bisglycinate chelateyes
Ritual Essential for Women 18+ Multivitamin$$$ 2 capsules44%iron bisglycinateyes
Pure Encapsulations $$1 capsule165%iron bisglycinateyes
MegaFood Blood Builder$$$1 tablet144%iron bisglycinateno
Nature Made Iron$1 tablet361%ferrous sulfateyes
SFI Health Chewable Iron Chelate$$1 chewable167%ferrochel ferric trisglycinate chelateno
Pure Encapsulations Iron Liquid$$$1 tsp83%ferric pyrophosphateyes
FullWell Iron Bump$$$1 capsule139%ferrous bisglycinateyes
Mary Ruth’s Organic Toddler Iron Liquid Drops$$30 drops50% (1- to 3-year-olds)ferrous bisglycinate chelateyes
  • Quality: The iron supplements are tested for quality and purity, ideally by a third-party organization.
  • Iron type: The supplements contain easily absorbed forms of iron.
  • Other nutrients: The supplements are free of nutrients that impair iron absorption and may contain nutrients that enhance absorption.
  • Dose: The supplements contain an effective dose of iron.
  • Price: We included products to suit a variety of budgets.
  • Forms: We included iron supplements in several forms, including liquids and chewables, to suit different preferences and tolerances.
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Iron is an essential mineral present in:

  • Hemoglobin: This protein transports oxygen from your lungs to your tissues.
  • Myoglobin: This is another protein that carries and stores oxygen for your muscles.

Iron is also essential for:

  • brain cell development
  • physical growth
  • hormone synthesis
  • muscle metabolism

To support these important processes, your body needs a steady supply of iron from your diet.

Iron exists in two forms in nature:

  • Heme iron: This iron is found in animal-derived foods. The human body readily absorbs it.
  • Non-heme iron: This form is found in plant-based and iron-fortified foods. The body doesn’t absorb it as well as it does heme iron.

You can also take iron supplements. Iron supplements may be necessary for people who don’t get enough iron in their diet and those with increased iron needs.

Types of iron

For people who need an iron supplement, choosing the right one can feel overwhelming. There are so many options, not to mention different forms and doses.

Supplemental iron comes in different forms, including:

  • ferrous sulfate
  • ferrous fumarate
  • ferrous bisglycinate
  • ferrous gluconate

While all these forms can effectively raise iron levels, some are a bit harder on your digestive system.

For example, ferrous sulfate is one of the most common forms of iron. But it’s more likely to cause gastrointestinal side effects like nausea and constipation.

Meanwhile, ferrous bisglycinate is highly absorbable and unlikely to cause side effects. Ferrous bisgycinate chelate is often considered one of the best-tolerated iron supplements.

Additionally, iron supplements come in various doses, which can increase the risk of side effects.

Taking higher doses of iron — 45 mg or more per day — is more likely to cause gastrointestinal side effects than lower doses.

Here’s a more in-depth overview of the types of iron you might find in popular supplements, including their bioavailability, affordability, and side effects:

FormBioavailabilityAffordabilitySide effects
Iron bisglycinate
chelate 		highly absorbable a bit more expensive than other forms of ironminimal gastrointestinal side effects compared with ferrous sulfate
Ferrous sulfatewell-absorbedinexpensivein high doses, may cause gastrointestinal side effects like constipation
Ferric sulfateless bioavailable than iron bisglycinate chelate and ferrous sulfate inexpensivein high doses, may cause gastrointestinal side effects like constipation
Ferrous fumarate well absorbedinexpensivein high doses, may cause gastrointestinal side effects like constipation

Who should take iron supplements?

People with adequate iron stores should aim to meet their iron needs through foods rather than supplements. However, you might need an iron supplement if you:

  • are treating an existing iron deficiency
  • have low iron stores
  • are trying to maintain healthy iron levels

People at risk of developing an iron deficiency who may benefit from an iron supplement include:

  • infants and kids
  • pregnant people
  • people with heavy menstrual bleeding
  • people with certain forms of cancer, such as colon cancer
  • people with gastrointestinal disorders, such as celiac disease and Crohn’s disease
  • people with heart failure
  • people who frequently donate blood
  • athletes

Warning about iron and children

Health experts do not recommend giving an iron supplement to your child unless a healthcare professional directs you to do so. Children are more susceptible to iron toxicity than adults.

Some people with iron deficiency anemia may need iron infusions if:

  • oral iron supplementation does not work
  • their bodies can’t properly absorb iron
  • their iron losses are too great to be treated with oral supplements

Overall, it’s wise to talk with a healthcare professional to find out whether an iron supplement is right for you.

How to take iron supplements

The typical treatment for iron deficiency anemia is taking daily oral iron supplements for at least 3 months to replenish iron stores.

Healthcare professionals may recommend some people continue to take iron supplements even after their hemoglobin levels return to normal.

For these people, taking an iron-only supplement is a good idea because other nutrients commonly found in multivitamins, such as calcium, may inhibit iron absorption.

Additionally, experts recommend taking iron supplements between meals and avoiding pairing them with foods or beverages that may inhibit iron absorption, such as:

  • tea
  • coffee
  • milk

Instead, take iron with a source of vitamin C, such as orange juice or bell peppers. Vitamin C can help enhance iron absorption.

In terms of supplement forms, one of the best iron supplements for anemia that’s unlikely to cause constipation is ferrous bisglycinate chelate. It’s highly absorbable and gentle on the digestive system, making it a smart choice for those with sensitive stomachs.

Certain iron supplements are more likely to cause side effects than others.

Potential side effects of taking iron supplements include:

  • constipation
  • diarrhea
  • nausea
  • abdominal pain

Iron can be toxic if taken in very high doses. To reduce the risk of side effects and toxicity, avoid exceeding the established tolerable upper intake levels for iron supplements unless a healthcare professional recommends it.

These levels are as follows:

  • 40 mg per day for babies and kids
  • 45 mg per day for teens and adults

Finally, it’s important to keep iron supplements out of reach of children because they are more susceptible to iron toxicity than adults.

Children may mistake iron supplements for candy and ingest large amounts, which can be fatal.

Drug interactions

Iron supplements may reduce the absorption of medications used to treat Parkinson’s disease.

Iron supplements may lower the effectiveness of levothyroxine, a common drug used to treat:

  • hypothyroidism, also called an underactive thyroid
  • goiter
  • thyroid cancer

On the other hand, some medications — such as proton pump inhibitors, which treat acid reflux or stomach ulcers — can reduce iron absorption because they lower gastric acid secretion, which plays a key role in iron uptake.

When to contact a doctor

Having too little iron in your body can cause symptoms such as:

  • fatigue
  • weakness
  • difficulty concentrating
  • shortness of breath

Some people are more at risk of developing iron deficiency anemia, including:

  • people with heavy periods
  • pregnant people
  • people with health conditions that cause nutrient malabsorption

If you think you may have an iron deficiency, visit a healthcare professional. They can check your iron levels with a blood test.

Do not try to treat an iron deficiency on your own. Even though most people respond well to oral iron supplements, some may need iron infusions to effectively increase their iron levels.

It’s important to consider several factors when choosing an iron supplement, including the type of iron, provided dose, and product quality and safety.

Dosing

Here are the current Recommended Dietary Allowances for iron in healthy teens and adults:

14 to 18 years19 to 50 years51+ years
11 mg for males8 mg for males8 mg for males
15 mg for females18 mg for females8 mg for females
27 mg while pregnant27 mg while pregnant—
10 mg while nursing9 mg while nursing—

For kids and babies, the Recommended Dietary Allowances are:

Birth to 6 months7 to 12 months1 to 3 years4 to 8 years9 to 13 years
0.27 mg for males and females11 mg for males and females7 mg for males and females10 mg for males and females8 mg for males and females

Keep in mind that if you’re low on iron, you’ll need more iron than most other people need each day.

If you have low iron stores, have a deficiency, or need extra iron for any reason, a healthcare professional can recommend a dosage that fits your needs.

Many forms of supplemental iron are effective for increasing iron levels.

Ferrous forms of iron tend to be more bioavailable than ferric iron, meaning your body more easily absorbs them.

However, some forms of iron, including ferrous sulfate, are more likely to cause gastrointestinal side effects like constipation than other forms, such as iron bisglycinate chelate.

So, iron bisglycinate chelate is a good overall option for raising iron levels that’s also gentle on the stomach.

Meanwhile, iron supplements come in several options, including liquids, capsules, and chewable products. Liquid and chewable iron supplements are a good choice if you cannot tolerate pills or capsules.

Some people, such as those with health conditions that cause nutrient malabsorption, may require iron infusions. These are administered and monitored by a healthcare team.

If you have iron deficiency anemia, ferrous forms of iron, such as ferrous sulfate, tend to be more bioavailable than ferric iron.

Iron bisglycinate chelate is also effective for treating iron deficiency anemia. Plus, it’s gentle on the stomach. It’s often preferred over ferrous and ferric salts because it’s less likely to cause gastrointestinal side effects like constipation.

The amount of iron you should take depends on your iron levels.

For people with iron deficiency, the typical recommendation is to take divided daily doses to reach 100 mg to 200 mg of elemental iron per day.

However, research suggests that taking smaller doses of iron once daily and taking iron every other day may help improve absorption and tolerability compared with taking large daily doses of iron.

Many forms of iron are gentle on the stomach and less likely to cause gastrointestinal side effects.

If you need an iron supplement but are concerned about potential side effects like constipation, it’s best to choose a supplement that contains iron in the form of iron bisglycinate chelate over supplements that contain ferric or ferrous salts, such as ferrous sulfate.

Iron is best absorbed on an empty stomach, so it’s recommended to take iron first thing in the morning, apart from meals and beverages like coffee or milk. However, some research shows that consuming iron supplements with a vitamin C-rich beverage, like orange juice, can significantly increase iron absorption.

While it’s best to take iron on an empty stomach, if iron supplements make you feel queasy, it’s OK to take them with a small meal or snack.

Iron is an important mineral that’s necessary for oxygen transport and the formation of healthy red blood cells.

While it’s always best to fulfill your iron needs through a diet high in iron-rich whole foods, supplements may sometimes be necessary to help you reach your daily iron needs.

Many types of iron supplements are available and contain varying doses and forms of the mineral.

Consult a healthcare professional before taking any new supplement, and consider the factors mentioned above to help you choose a high quality product.