Iron Supplements: What to Know Before You Buy

Iron supplements are available in different forms, strengths and combinations, and the numbers shown on product labels can be difficult to compare.

You may see ingredients such as ferrous fumarate, ferrous sulfate, ferrous gluconate, iron bisglycinate or other iron compounds. Some products contain iron alone, while others combine it with vitamin C, B vitamins, folate or other nutrients.

One of the most important things to understand is that the total weight of an iron compound is not necessarily the same as the amount of iron it provides.

This guide explains iron forms, elemental iron, serving information, ingredient combinations and important safety considerations to check before choosing an iron supplement.

What Is Iron?

Iron is an essential mineral required by the body.

It is an important component of haemoglobin, the protein in red blood cells involved in transporting oxygen around the body. Iron is also present in myoglobin and a variety of enzymes.

Iron comes from food as well as supplements.

Dietary sources can include:

  • red meat
  • poultry
  • fish
  • eggs
  • legumes such as lentils, chickpeas and beans
  • wholegrain foods
  • iron-fortified cereals
  • dark green leafy vegetables
  • tofu and other plant foods

Your iron requirements depend on factors including age, sex and life stage, so a supplement should not automatically be assumed to be necessary simply because iron is an essential nutrient.

Who Is This Guide For?

This guide may be useful if you:

  • have been advised to consider an iron supplement
  • are comparing different iron products
  • want to understand what elemental iron means
  • are confused by different iron compounds on labels
  • are comparing tablets, capsules or liquid products
  • want to understand products containing iron plus vitamin C or other nutrients
  • already take a multivitamin, prenatal formula or other iron-containing supplement
  • want to compare serving sizes and cost per serve

This guide provides general purchasing information. It is not intended to diagnose iron deficiency or determine the amount of iron an individual should take.

Do Not Self-Diagnose Iron Deficiency

Feeling tired does not automatically mean that you have low iron.

Symptoms that can occur with iron deficiency or anaemia can also have many other causes.

Healthdirect advises that iron status can be investigated using blood tests. Depending on the situation, your doctor may check measures such as haemoglobin and iron stores and may investigate why your iron level is low.

This matters because iron deficiency can occur for different reasons, including:

  • inadequate dietary intake
  • blood loss
  • menstruation
  • pregnancy
  • problems absorbing nutrients
  • certain health conditions

If you think you may have iron deficiency, the appropriate first step is professional assessment rather than simply choosing the strongest iron supplement available.

Iron Deficiency Is Not the Same as Iron-Deficiency Anaemia

Iron status exists on a spectrum.

A person can have reduced iron stores before developing iron-deficiency anaemia.

Anaemia can also have causes other than iron deficiency, including deficiencies of other nutrients and various medical conditions.

This is another reason blood testing and medical assessment are important when deficiency or anaemia is suspected.

What Does Elemental Iron Mean?

This is one of the most useful label concepts to understand when comparing iron supplements.

Iron is normally supplied as part of a larger compound.

For example, a label may list a quantity of ferrous fumarate, ferrous sulfate or another iron compound and then state that this quantity is equivalent to a smaller amount of iron.

The weight of the entire compound is therefore not the same as the amount of iron actually provided.

When comparing products, look for wording such as:

“equivalent to iron”

or another declaration indicating the amount of iron supplied by the labelled dose.

Do not compare two products solely by looking at the larger compound weight.

Common Iron Forms

Iron products may use several different compounds.

Examples you may encounter include:

  • ferrous fumarate
  • ferrous sulfate
  • ferrous gluconate
  • iron bisglycinate or other chelated iron forms
  • other ferrous or ferric iron compounds

The name of the iron compound is only one part of the comparison.

Also check:

  • the amount of iron provided per labelled dose
  • serving size
  • number of tablets or capsules required
  • additional ingredients
  • directions
  • warnings
  • cost per serve

Do not assume that a product is automatically stronger, gentler or more appropriate simply because it uses a particular form of iron.

Compare Iron Provided — Not Just Tablet Strength

Two iron tablets can have very different numbers printed on their labels because manufacturers may describe the amount of the iron compound as well as the amount of iron it provides.

To compare products properly:

  1. identify the iron compound
  2. find the amount of iron it is equivalent to providing
  3. check how many tablets, capsules or millilitres make one dose
  4. compare the amount of iron provided by that complete dose

This gives a much more useful comparison than container size or front-label numbers alone.

Supplement Strength vs Treatment for Iron Deficiency

There is an important difference between choosing a general nutritional supplement and medically treating diagnosed iron deficiency or iron-deficiency anaemia.

Healthdirect notes that over-the-counter nutritional supplements may not provide the amounts used to medically treat iron-deficiency anaemia.

If blood tests show that you are iron deficient, your doctor or pharmacist may recommend a particular oral iron medicine, dose and duration based on your individual circumstances.

Do not try to recreate a medical treatment dose by taking several lower-strength supplements together.

Tablets, Capsules or Liquid Iron?

Oral iron products are available in several formats.

Tablets

Iron tablets provide a pre-measured dose and are commonly used in both supplements and iron medicines.

Check:

  • iron form
  • amount of iron provided
  • tablets per dose
  • tablet size
  • directions and warnings

Capsules

Capsules are another pre-measured option.

As with tablets, compare the amount of iron provided rather than assuming that one capsule is equivalent to another product's capsule or tablet.

Liquid Iron

Liquid products may be preferred in some circumstances, including when swallowing tablets is difficult.

When comparing liquids, check:

  • iron provided per measured dose
  • how the dose should be measured
  • serving instructions
  • storage requirements
  • additional ingredients

Some oral liquid iron medicines can stain teeth, so follow the specific product directions carefully.

Iron & Vitamin C

Vitamin C can increase the absorption of non-haem iron.

For this reason, some iron products include vitamin C as part of the formula.

Vitamin C can also be obtained from foods such as:

  • citrus fruit
  • kiwifruit
  • berries
  • capsicum
  • tomatoes
  • green vegetables

A product containing iron plus vitamin C is not automatically more appropriate than an iron-only product. Consider the total formula and any other supplements you already use.

Food & Drinks Can Affect Iron Absorption

What you consume around the same time as iron can affect absorption.

Healthdirect notes that iron absorption can be reduced when iron is taken alongside products such as:

  • tea
  • coffee
  • some calcium-containing foods or supplements
  • certain other dietary components

However, the correct timing can differ depending on whether you are using a nutritional supplement or a medicine prescribed or recommended to treat deficiency.

Follow the directions on your specific product and ask your pharmacist if you are unsure how to separate iron from food, drinks, medicines or other supplements.

Iron Supplements Can Cause Gastrointestinal Side Effects

Oral iron can cause gastrointestinal effects in some people.

These may include:

  • constipation
  • nausea or stomach discomfort
  • changes in bowel habits
  • dark-coloured stools

Dark stools are a recognised effect of oral iron products.

If side effects are difficult to manage, speak with your doctor or pharmacist rather than stopping prescribed treatment or changing the dose without advice.

Different products, doses and dosing schedules may be handled differently depending on the individual situation.

Iron Supplements & Medicines

Iron can interact with some medicines or reduce their absorption.

Examples can include certain:

  • antibiotics
  • thyroid medicines
  • osteoporosis medicines
  • other medicines whose absorption is affected by minerals

For example, Healthdirect advises that iron supplements need to be separated from doxycycline, and some thyroid and osteoporosis medicines also have specific instructions regarding iron and other mineral supplements.

If you take regular medicines, tell your doctor or pharmacist about every vitamin, mineral and supplement you use.

Do not assume that taking them several minutes apart is sufficient. The required separation time depends on the medicine.

Check Whether You Already Take Iron

Iron is commonly included in combination supplements.

Check products such as:

  • multivitamins
  • women's multivitamins
  • pregnancy and prenatal supplements
  • multi-mineral products
  • B-vitamin combinations
  • other nutritional formulas

If you use several supplements, look at all labels together.

This helps you understand your total supplemental iron intake and prevents accidental duplication.

Check Other Added Nutrients

Iron supplements may also contain:

  • vitamin C
  • folate or folic acid
  • vitamin B12
  • vitamin B6
  • other B vitamins
  • minerals
  • other active ingredients

A longer formula is not automatically better.

Consider whether you need the additional nutrients and whether they are already present in other supplements you use.

Pregnancy & Iron

Iron requirements increase during pregnancy.

The Australian and New Zealand Nutrient Reference Values list a higher recommended dietary intake of iron during pregnancy than for most non-pregnant adults.

This does not mean every pregnant person should independently choose a high-strength iron supplement.

Iron requirements, blood results and tolerance can differ substantially during pregnancy.

If you are pregnant or planning pregnancy, discuss iron supplementation with your doctor or midwife, particularly if you have been told that your iron stores or haemoglobin are low.

If you already use a prenatal supplement, check how much iron it contains before adding another product.

Vegetarian & Vegan Diets

Plant foods provide non-haem iron.

The body generally absorbs non-haem iron less efficiently than haem iron from animal foods, and the composition of a meal can affect how much is absorbed.

Plant-based sources can include:

  • legumes
  • tofu
  • wholegrains
  • iron-fortified cereals
  • nuts and seeds
  • green leafy vegetables

Eating vitamin C-rich foods with plant sources of iron can increase non-haem iron absorption.

If you follow a vegetarian or vegan diet and are concerned about your iron intake, an Accredited Practising Dietitian or appropriate healthcare professional can help assess your overall diet and individual requirements.

Iron Requirements Are Different for Different People

There is no single iron requirement that applies to everybody.

Australian Nutrient Reference Values differ according to factors such as:

  • age
  • sex
  • menstruation
  • pregnancy
  • breastfeeding
  • life stage

For example, people who menstruate generally have higher iron requirements than adult men and post-menopausal women.

This is why the highest-strength supplement is not automatically the most suitable product.

Can You Have Too Much Iron?

Yes.

Iron is essential, but excessive iron can be harmful.

The Australian Nutrient Reference Values include an Upper Level of Intake for iron because excessive intake can cause adverse effects.

Healthdirect advises that iron supplements should be used under medical supervision when treating iron deficiency because taking more than recommended can cause iron poisoning.

Do not take extra iron simply on the assumption that more will provide greater benefit.

What About Haemochromatosis?

Haemochromatosis is a genetic condition in which the body absorbs and stores too much iron.

People with haemochromatosis or another condition involving iron overload should not self-select iron supplements.

If you have haemochromatosis, a family history of the condition, abnormal iron blood results or have previously been advised that your iron levels are high, seek medical advice before taking a product containing iron.

Keep Iron Supplements Away From Children

Iron deserves particular care around children because excessive amounts can cause serious poisoning.

Store iron supplements:

  • out of sight and reach of children
  • in their original packaging
  • with the lid or child-resistant closure properly secured
  • away from food or confectionery where tablets could be mistaken for something edible

If a child or adult may have swallowed an excessive amount of iron, contact the Poisons Information Centre on 13 11 26 for advice.

Do not wait for symptoms to appear before seeking advice after a suspected poisoning.

For a medical emergency, call 000.

Food First

Iron is naturally available from food, and dietary intake should be considered before adding supplements.

Iron-rich foods can include:

  • lean red meat
  • poultry
  • fish
  • eggs
  • legumes
  • tofu
  • wholegrain bread and cereals
  • iron-fortified breakfast cereals
  • dark leafy green vegetables

Whether food alone is sufficient depends on your individual requirements and circumstances.

If deficiency has been diagnosed, follow your healthcare professional's treatment advice rather than attempting to manage it solely by changing foods or using a general nutritional supplement.

Compare Cost Per Serve Carefully

Iron products can differ significantly in bottle size, dose and amount of iron supplied.

For a meaningful comparison, check:

  • container price
  • number of tablets, capsules or liquid serves
  • number required per labelled dose
  • amount of iron provided per dose
  • additional ingredients
  • number of usable serves

Do not choose purely on cost per tablet because the amount of iron supplied by each tablet may differ.

How to Compare an Iron Supplement Before You Buy

Before choosing a product, ask:

  • Have I actually been advised that I need supplemental iron?
  • What form of iron does the product contain?
  • How much iron does the labelled dose actually provide?
  • Am I comparing elemental iron rather than only the weight of the compound?
  • How many tablets, capsules or millilitres make one dose?
  • Does the product contain vitamin C or other added nutrients?
  • Am I already taking iron in a multivitamin, prenatal or other supplement?
  • Could the product interfere with any medicines I take?
  • What directions and warnings are on the label?
  • How many usable serves are in the container?
  • What is the cost per serve?
  • If iron deficiency has been diagnosed, does this product and dose match the advice from my healthcare professional?

Explore Iron Supplements

Browse current Iron products at Elite Vitamin Zone.

You can also explore the complete Vitamins & Minerals range.

Or return to Vitamins & Minerals Guides for more practical supplement-comparison information.

Frequently Asked Questions

How do I know if I need an iron supplement?

Do not rely on symptoms alone. Iron deficiency can be assessed using blood tests, and tiredness or other symptoms can have many different causes. Speak with your doctor if you think your iron may be low.

What is elemental iron?

Elemental iron is the amount of iron actually provided by an iron compound. A product may list a larger quantity of ferrous fumarate, ferrous sulfate or another compound and then state that it is equivalent to a smaller amount of iron. The equivalent iron amount is the more useful figure when comparing products.

Are all iron supplements the same strength?

No. Products can contain different iron compounds, different amounts of iron per dose and different serving instructions. Always compare the detailed label.

Which form of iron is best?

There is no single product that is automatically appropriate for everybody. The correct choice can depend on the reason iron is being used, the amount required, tolerance, medicines and professional advice. If you are treating diagnosed deficiency, follow your doctor or pharmacist's recommendation.

Can I take iron because I feel tired?

Feeling tired does not confirm iron deficiency. Low iron is one possible cause among many. Blood tests can help determine whether iron deficiency or anaemia is present.

Why do some iron supplements contain vitamin C?

Vitamin C can improve the absorption of non-haem iron, which is why it is included in some formulas. Vitamin C can also be obtained from foods as part of your diet.

Can tea or coffee affect iron?

Yes. Tea and coffee consumed around the same time can reduce iron absorption. Follow the directions for your specific product and ask your pharmacist about timing if you are using iron to treat a diagnosed deficiency.

Why do iron tablets make stools dark?

Dark stools are a recognised effect of oral iron products. Iron can also cause constipation and other gastrointestinal effects. If you have concerns about symptoms or side effects, speak with your doctor or pharmacist.

Can iron supplements interact with medicines?

Yes. Iron can affect the absorption of some medicines, including certain antibiotics, thyroid medicines and osteoporosis medicines. Ask your pharmacist how your medicines and supplements should be timed.

Can I take iron during pregnancy?

Iron requirements increase during pregnancy, but the need for a supplement and the appropriate dose depend on individual circumstances and blood results. Discuss supplementation with your doctor or midwife, particularly if you already take a prenatal formula containing iron.

Can you take too much iron?

Yes. Excessive iron can be harmful and can cause poisoning. Do not exceed the product directions or combine multiple iron-containing supplements without professional advice.

Why must iron supplements be kept away from children?

An excessive amount of iron can cause serious poisoning. Keep iron products securely out of children's reach. If accidental ingestion is suspected, contact the Poisons Information Centre on 13 11 26 for advice.

Further Information

For additional Australian information about iron, deficiency, dietary intake and iron medicines, refer to:

Product formulas, iron forms, strengths, serving sizes, directions and warnings can change. Always check the current product label before purchase and use.

Important Information

This guide provides general information about iron supplements and factors customers may wish to consider when comparing products. It is not a substitute for individual medical, nutrition or pharmacy advice and should not be used to diagnose or treat iron deficiency or anaemia.

Always read the label and follow the directions for use. Iron supplements should not be taken unnecessarily or in excessive amounts. If you think you may have iron deficiency, have abnormal blood results, are pregnant or breastfeeding, have haemochromatosis or another health condition, take medicines, or are unsure whether an iron supplement is appropriate for you, seek advice from an appropriate healthcare professional.

Keep iron supplements out of reach of children. If an excessive amount may have been swallowed, contact the Poisons Information Centre on 13 11 26. In a medical emergency, call 000.