Best iron supplements 2026: reviewed by nutrition experts

Iron deficiency is one of the most common nutrient deficiencies. You're most at risk of deficiency if you're vegan or vegetarian, menstruating, pregnant or post-menopausal. 

Iron supplements can help to get your iron stores back to optimal levels, but some types can cause unwanted digestive side effects. It's important to find one you can tolerate, as you typically need to supplement with iron regularly for several months for the best results.

We've reviewed a wide range of iron supplements to uncover the best options for optimal iron absorption with minimal ill-effects. 

Why you can trust our iron supplement reviews

At Which? our reviews are completely independent. We buy every supplement we test, looking at a range of prices and types to accommodate different budgets and needs.

Every supplement we review is analysed by me – Which?'s lead health and wellbeing researcher, Shefalee Loth, a registered public health nutritionist – along with consultant dietitian Sophie Medlin.

We both have many decades of experience working on supplements. Sophie has advised on supplement development, and I have been scrutinising supplements and supplement claims for Which? for more than a decade.

We've spent many hours reviewing the available evidence to determine optimal iron supplement formats and dosages, as well as the less-desirable side effects and additives, to uncover the best options for you. 

We also consider claims made, cost per daily dose and more, so you can be confident that our recommendations will help you get the best value and quality.

Any products we think are worth recommending are tested at an independent specialist lab to check that they contain what they claim to.

The best iron supplements

Only logged-in Which? members can view our full iron supplement reviews and scoring, including the top-rated products.

Join Which? Today to get instant access to our test results and Best Buy recommendations below, as well as revealing our Great Value picks.

The iron supplements we assessed

A selection of popular iron supplements included in our assessment is listed in alphabetical order below.

Only logged-in Which? members can view our full verdict on each. Join Which? to get instant access to our test results and recommendations.

Active Iron 

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Available from Active Iron (£16.99 for 30), Boots (£16.50 for 30), Holland & Barrett (£16.99 for 30)

Cost per daily dose 57p

BetterYou Iron Spray 10mg 

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Available from BetterYou (£14.99 for 32 doses), Boots (£10.80 for 32 doses), Holland & Barrett (£14.95 for 32 doses)

Cost per daily dose 47p

Boots Gentle Iron (max strength 20mg)

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Available from Boots (£6.10 for 60)

Cost per daily dose 10p

Floradix Liquid Iron formula

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Available from Boots (£15.75 for 250ml), Floradix (£22.15 for 500ml), Holland & Barrett (£25.49 for 500ml)

Cost per daily dose 89p

Lamberts Iron (as citrate)

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Available from Amazon (£9.85 for 100), Lamberts (£9.50 for 100)

Cost per daily dose 10p

New Leaf Iron gummies 

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Available from Holland & Barrett (£16.95 for 60), New Leaf (£19.95 for 120), Superdrug (£19.95 for 120)

Cost per daily dose 67p

Nutravita Iron Bisglycinate

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Available from Nutravita (£8.99 for 180)

Cost per daily dose 10p

Nutrition Geeks Iron

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Available from Amazon (£9.99 for 365), Nutrition Geeks (£9.99 for 365)

Cost per daily dose 3p

Solgar Gentle Iron (iron bisglycinate)

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Available from Boots (£13 for 90), Holland & Barrett (£16.10 for 90), Solgar (£26.16 for 180)

Cost per daily dose 15p

Spatone Daily Iron shots (apple flavour)

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Available from Boots (£16 for 28 sachets), Holland & Barrett (£16.99 for 28 sachets), Spatone (£16.99 for 28 sachets)

Cost per daily Dose 57p

Vitabiotics Feroglobin capsules

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Available from Boots (£5.49 for 30), Holland & Barrett (£6.15 for 30), Vitabiotics (£6.15 for 30)

Cost per daily dose 21p

Zipvit Iron Bisglycinate

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Available from Zipvit (£9.99 for 365)

Cost per daily dose 3p

Note: cost per serving is based on the manufacturer's recommended serving size and the RRP (recommended retail price); however, products are frequently discounted. We're not able to show every retailer, and cheaper prices may be available.

Best magnesium supplements – get our expert picks for magnesium, plus advice on the best type to buy

More iron supplement reviews

The remaining iron supplements we tested are listed below in alphabetical order.

Only logged-in Which? members can view our full iron supplement test results. Join Which? to get instant access today.

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How we review iron supplements

When comparing iron supplements to find the best, our nutrition experts consider the following key factors:

Bioavailability What form of iron is used in the supplement and what the science says about how well it's absorbed. Does it include any extras that aid absorption, for example vitamin C?

Tolerability How well the particular form of iron used in each supplement is tolerated. Some types of iron supplement are known to cause digestive issues, including constipation and stomach irritation. So to ensure you get a format you can stick to, we look for forms known to be gentle on the stomach.

Dose How much iron is in the supplement, and what's the recommended dose? Is it too low to be effective for most people, or higher than might be needed? The daily recommendation or Nutrient Reference Value (NRV) for iron is 14mg, and the safe upper limit is 45mg. Too much iron can be dangerous. However, if you are anaemic, you may be prescribed higher doses for a set period by your GP. This is only recommended under medical supervision though.

Additives Other than active ingredients, such as vitamins and minerals, what else does the supplement contain and is it necessary or simply filler?

We also note the size and shape of the tablet or capsule, and alert you to any that are particularly large or small so you can pick the format that works best for you.

Lab testing to check iron levels We send the top-scoring supplements from our assessment to an independent lab for testing to make sure they contain the amount of iron claimed on the label. Only those that pass this testing make it to a Best Buy. 

Iron aupplements that do well in our testing and are also significantly cheaper than the others we've reviewed are labelled as Great Value buys.

Why you can trust us: at Which? we're free from manufacturer and retailer influence. Find out more about our impartiality and how your support helps us to stay editorially independent

How much iron do you need?

The Nutrient Reference Value (NRV) for iron in the UK (and EU) is 14mg a day. This is what's used on supplement labelling, where the iron content is given in mg and also as a percentage of the NRV.

However, this is a broad-strokes recommendation, and the NHS recommends slightly different values depending on your gender and age. Essentially, you need more iron if you're menstruating or pregnant, otherwise you can get away with less than 14mg.

Your body needs more iron during times of growth too, such as adolescence. The British Dietetic Association recommends adolescent males aged 11-18 have 11.3mg iron a day, and adolescent females aged 11-18 have 14.8mg a day.

The safe upper limit for iron for everyone aged 14+ is 45mg a day – this includes iron from food and supplements. For babies and children under 14, the safe upper limit is 40mg a day. 

The NHS warns that taking iron supplements containing more than 20mg can cause side effects such as constipation, nausea and stomach pain. Very high doses can be fatal, especially for children, so it's important to keep iron supplements out of reach – especially if they're in a tempting format, such as gummies.

If you've been prescribed a higher dose by a doctor, you should take this as it will be relevant to your personal circumstances and iron levels – for example, if you've been diagnosed with iron deficiency anaemia or have heavy or frequent periods.

What are the signs of iron deficiency?

Iron is a key nutrient that plays a central role in many bodily functions. It transports oxygen around your body, supports your immune system and helps cognitive function. If you've got low iron levels, you can feel tired, weak, short of breath and find it hard to concentrate. You may also be paler than usual.

If you've got very low iron levels and have iron deficiency anaemia, symptoms can be more severe. These include a weakened immune system, heart palpitations, hair loss and brittle nails, and itchy skin.

Some people are more at risk of iron deficiency:

• Infants, young children and adolescents
• If you're pregnant or menstruating
• Vegans and vegetarians
• People with gastrointestinal and digestive issues.

If you have any of the symptoms listed, whether persistent or new, it's best to speak to your doctor. They can organise a blood test to measure your iron levels, and also speak to you about your symptoms and rule out any other possible causes. 

If you are diagnosed with iron deficiency anaemia, your doctor should give you a plan of action and is likely to prescribe iron supplements. These will typically be higher strength than the supplements you can buy without a prescription.

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What's the best type of iron?

There are two types of iron: haem and non-haem.

Haem iron is the most easily absorbed type and is found in animal-based foods, such as beef and pork. 

Non-Haem iron is found in plant foods, such as spinach. It's not as easily absorbed, but taking it with foods rich in vitamin C helps improve absorption.

Most iron supplements are derived from non-haem sources to make them suitable for vegetarians and vegans, but do check the packaging to make sure.

The forms of iron usually found in supplements include: ferrous bisglycinate, ferrous gluconate and ferrous sulphate.

These all have different bioavailability, and some can cause more gastric side effects than others. For example, ferrous bisglycinate is absorbed well and has fewer reported side effects such as nausea and constipation. 

Ferrous sulphate is also highly bioavailable, but more people tend to experience unpleasant side effects when taking it, such as stomach cramps, nausea and constipation.

If you do experience digestive side effects when taking an iron supplement, try taking it with food and increasing your water and fibre intake, as this can help.

Best food sources of iron 

Most people should be able to get all the iron they need from their diet. However, if you're in one of the higher-risk deficiency groups or don't eat much red meat, then you may want to consider supplementing. 

Good food sources of iron include red meat and offal (although it's important not to eat liver if you're pregnant because of high levels of vitamin A, which can be dangerous during pregnancy). 

Fish and chicken contain lesser amounts but are also good sources. 

Plant-based sources of iron include: beans, peas, lentils, dark green vegetables such as kale, spinach and broccoli, and nuts and seeds. 

Many foods, such as breakfast cereals, are fortified with iron. This means they have iron added to them.

By law, all bread (and flour), other than wholemeal, sold in the UK must be fortified with iron. 

What is the best time to take iron supplements?

Always check any specific instructions on the pack, but generally you should take iron supplements on an empty stomach, either around an hour before eating or a couple of hours after eating. 

However this can make some people feel nauseous and cause stomach aches. If this is the case with you, take it with food.

Some studies have shown that taking iron supplements every other day, instead of every day, can reduce side effects and can actually help absorption – proving as effective as taking daily supplements. 

Taking your iron with a vitamin C source will increase its absorption too. Either wash it down with a glass of orange juice or eat it alongside citrus fruit, broccoli, peppers or potatoes. 

What to avoid with iron supplements

Avoid taking iron supplements at the same time as tea, coffee, dairy, wine, bran cereals and wholemeal bread. This is because these products contain nutrients and compounds that inhibit iron absorption in the gut, including tannins and calcium.

Who shouldn’t take iron supplements?

Iron can interfere with some medications, such as antibiotics and those for seizures or Parkinson's, so check with your doctor before starting iron supplements.

Other groups that shouldn't take iron supplements without checking with their doctor include people with any conditions that affect blood, red blood cells, or iron absorption; people who have frequent blood transfusions; and people with stomach and bowel issues. 

If you have any doubts, it's always best to check with a health professional before taking a supplement.

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Our supplement experts

Which? nutritionist Shefalee Loth and consultant dietitian Sophie Medlin are no strangers to analysing supplements to uncover the best:

'We've spent the past year poring over ingredients lists and the latest clinical evidence, as well as asking brands for the data to support their claims, so that we can uncover the best supplements you can buy.

Other supplements recently reviewed include the best protein powders, creatine supplements, probiotic supplements and vitamin D supplements.'

Shefalee Loth, Which? principal researcher and nutritionist

Shefalee is a public health nutritionist with 20 years' experience, and has worked for the NHS, The London School of Hygiene & Tropical Medicine and World Cancer Research Fund.

At Which?, Shefalee is a principal researcher, researching and writing food and nutrition content for our magazine and website, and overseeing all our supplement reviews. She is also a media spokesperson and the research lead for our health and wellbeing reviews. She was previously a trustee at Sustain, the food and farming alliance and The Caroline Walker Trust.

Shefalee focuses on cutting through the hype to explain what you need to know about nutrition and healthy eating. From 'How bad is ultra-processed food?' to the 'Top gut health myths you need to know about' and 'What really works to cut cholesterol', she gives no-nonsense advice to help you make healthier choices and save money.

Sophie Medlin, consultant dietitian and founder of CityDietitians

Sophie Medlin is a well-recognised consultant dietitian with nearly 20 years' experience working across the NHS and academia and within her own private practice at CityDietitians. 

Sophie is chair of the British Dietetic Association for London.

With her in-depth knowledge of nutrition – both theoretical and applied – Sophie has helped to formulate supplements, giving her insight into the strengths and weaknesses of products and the manufacturing process.