If you are looking for the best iron tablets, the honest answer is that the best one is the one that fits your actual need: a well-absorbed ferrous form, an elemental iron amount you can read at a glance, vitamin C alongside it, a dose that follows a blood test rather than a hunch, and a maker who shows you the purity testing. This guide gives you the criteria to judge any iron tablet, ours included, without brand rankings or hype.
I am Dr. Miron, and iron is a mineral I want people to choose carefully. Iron contributes to the reduction of tiredness and fatigue and to normal oxygen transport in the body, so it earns its place when you genuinely need it. It is also the one supplement where more is not better, which is why I would rather give you a checklist than a league table.
Reviewed and updated: 2 November 2026
Best iron tablets: the quick answer (TL;DR)
- Test first: ask your GP for a blood test including ferritin before starting iron, and follow their dose if you are told to take more than a standard daily amount.
- Read the elemental iron: the number that matters is the iron itself, not the weight of the compound. Our tablet gives 14 mg of iron from 42 mg of ferrous fumarate.
- Pick a form you can live with: ferrous fumarate, sulfate, gluconate and bisglycinate are all used. Tolerance is personal, so choose something you will take for weeks, not days.
- Look for vitamin C: vitamin C increases iron absorption, so a formula that already contains it saves you remembering the orange juice.
- Key caution: keep iron out of reach of children, do not exceed the label dose, and avoid it entirely if you have been told you have haemochromatosis.
Our pick for this guide
Want iron with vitamin C already built in?
14 mg of iron per tablet (from 42 mg of ferrous fumarate) with 60 mg of vitamin C, 3 mcg of B12 and 200 mcg of folic acid, one tablet a day, vegan. A food supplement, not a replacement for medical advice.
From £8.76 · 30 tablets, one month
Shop Iron Tablets →Do you need iron tablets at all?
Before choosing between products, it is worth asking whether iron is the right thing to take. Tiredness has many causes, and low iron is only one of them. The people most likely to run short include those with heavy periods, pregnant women, regular blood donors, vegetarians and vegans, and people eating much less than usual. If that sounds like you, a quick GP blood test is the sensible first step, because it tells you whether your iron stores are actually low and how low.
This is also why I am cautious about iron for men and for women after the menopause. Their reference intake is lower, and iron they do not need can build up in the body. If a blood test has not shown a need, a varied diet is usually enough. Our pillar guide on how to increase ferritin walks through what ferritin is and what to do with the number once you have it.
Dinner with a glass of orange juice and the pouch on the table. I keep my iron close to the meal I will actually remember. Illustrative image
Iron forms compared: fumarate, sulfate, gluconate, bisglycinate and more
Iron supplements come in several chemical forms, and the label names them in different ways, which is where most of the confusion starts. Here is a plain-English tour.
- Ferrous fumarate: a ferrous (iron two) salt with a high proportion of elemental iron, roughly a third by weight. It is widely used and well absorbed. It is the form in our tablets.
- Ferrous sulfate: the most common form in standard pharmacy iron, with a lower elemental share (around 20% for the heptahydrate). It is well studied, and it is also the form most often linked with stomach side effects in trials.
- Ferrous gluconate: a gentler-sounding salt with a lower elemental share, around 12%, so you need more tablet for the same iron.
- Iron bisglycinate: iron bound to the amino acid glycine. Often marketed as the comfortable option; the evidence base is smaller than for the ferrous salts, so judge it on the elemental amount and how you get on.
- Iron citrate and other chelates: used in some liquids and powders. Again, read the elemental iron per serving rather than the compound weight.
- Liquids and slow-release tablets: liquids suit people who cannot swallow tablets, and slow-release formats are designed to release iron gradually. Both can change how much is absorbed and where in the gut it lands, so they are worth discussing with a pharmacist.
The honest summary is that no form is magic. Our own iron tablets uses ferrous fumarate with vitamin C, B12 and folic acid because it combines a well-absorbed ferrous salt with the nutrients that sit naturally alongside iron, and we also make a plain 14 mg ferrous fumarate tablet for people who want iron on its own.
If you want to go deeper on the two food forms of iron, our guide to haem versus non-haem iron explains why plant iron behaves differently from the iron in meat and fish.
Elemental iron: the number to read on the label
This is the single most useful label skill. Iron is sold as a compound (ferrous fumarate, say), and only part of that compound’s weight is actual iron. The label should state the elemental iron, because that is the figure your daily reference intake and the safety guidance are measured against.
Our tablet is a good worked example: 14 mg of iron, from 42 mg of ferrous fumarate. The fumarate is the carrier and the 14 mg is the iron, which is 100% of the daily Nutrient Reference Value. A tablet that simply says “ferrous sulfate 200 mg” is not telling you how much iron you are getting until you do the arithmetic, which is roughly a fifth of that weight for the heptahydrate form. When you compare two products, compare elemental iron per tablet and then the number of tablets per day.
The back of the pouch is where I look first: iron, vitamin C, B12 and folic acid, each with its percentage of the reference value.
Gentle on the stomach: what the evidence says
Stomach upset is the main reason people give up on iron, so it deserves honesty rather than a promise. According to PubMed, a systematic review of 111 studies covering more than 10,000 people compared the tolerability of different oral iron products, and found wide differences between them. In that pooled data, extended-release ferrous sulfate had the lowest rate of side effects and ferrous fumarate had a higher rate, although the studies varied a great deal in design (Cancelo-Hidalgo et al., 2013). A separate meta-analysis of 43 trials found that ferrous sulphate roughly doubled the odds of nausea, constipation and stomach discomfort compared with placebo (Tolkien et al., 2015).
What I take from this is that tolerance is individual and no label can guarantee a trouble-free experience. What reliably helps is practical: take iron with a little food if it upsets you, keep the dose sensible, and consider alternate-day dosing. In a trial in iron-depleted women, single doses on alternate days led to better fractional absorption than daily or twice-daily split doses (Stoffel et al., 2017). If constipation is your worry, we cover it properly in iron supplement without constipation.
How much iron is the right amount?
The UK reference intake for iron is 14.8 mg a day for women aged 19 to 49, and 8.7 mg a day for men and for women over 50. The EU label reference (NRV) used on supplement packs is 14 mg. The NHS advises that taking 17 mg or less a day of iron from supplements is unlikely to cause harm, and that you should only take a higher dose if a GP has advised it. High doses over time can cause stomach pain and constipation and, eventually, a build-up of iron in the body.
That is why a 14 mg tablet suits most people looking for an everyday daily amount, and why I am wary of very high-strength products sold without any mention of testing. If you are wondering whether a standard daily amount is enough for you, see is 14mg of iron a day enough. If your GP has found a low ferritin, follow their dosing plan, which may be higher and time-limited.
Absorption helpers and blockers: vitamin C, tea, coffee, calcium and timing
Two people can take the same tablet and absorb very different amounts, because food and drink around the dose matter. The helper worth knowing is vitamin C, which increases iron absorption. A review in the International Journal for Vitamin and Nutrition Research describes ascorbic acid as the most efficient enhancer of non-haem iron absorption, thanks to its reducing and chelating properties (Teucher et al., 2004). Building vitamin C into the tablet, as we do with 60 mg per tablet, means the helper is there in every dose.
The blockers are just as practical. In a study in adults, polyphenol-containing drinks were potent inhibitors of iron absorption from a bread meal: black tea reduced absorption by roughly 79 to 94%, and coffee, cocoa and several herbal teas also had a strong effect (Hurrell et al., 1999, PubMed). Calcium from milk, cheese and calcium supplements competes with iron, and antacids can lower absorption too. A gap of a couple of hours between your tablet and your tea, coffee or dairy is the simple fix.
Empty stomach or with food? Iron is absorbed best away from large meals, but if that leaves you queasy, taking it with a small amount of non-dairy food is a fair trade. Morning, lunchtime or evening all work, so pick the time you will remember. Our guide to taking iron tablets at night covers the evening question in more detail.
Lentils, spinach, chickpeas and a squeeze of orange. Food first, always. Illustrative image
Iron with B12 and folic acid: do combination tablets make sense?
Many UK buyers now choose an iron tablet that includes vitamin C, B12 and folic acid rather than iron on its own, and there is a logical reason. Iron contributes to the normal formation of red blood cells and haemoglobin, folic acid contributes to normal blood formation, and vitamin B12 contributes to normal red blood cell formation, so the three work in the same area of the body. Vitamin C then increases iron absorption. Our tablet carries 60 mg of vitamin C (75% of the reference value), 3 mcg of B12 (120%) and 200 mcg of folic acid (100%) alongside the iron.
A combination tablet is a convenience, not a necessity. If you only need iron, a plain tablet does the job, and if you take a multivitamin already, check the iron and folic acid amounts so you do not double up. We explain the pairing in more detail in ferrous fumarate, iron with vitamin C and folic acid.
5-star review on our store (Judge.me)
Everything together
“The combination is what convinced me to try this formula. I like knowing that the vitamin C, B12 and folic acid are included alongside the iron, and the tablets are easy enough to take each day.”
★★★★★ Alice M.
Tablets, capsules or liquid: format and price per day
Format is mostly about habit. Tablets are compact and portable, capsules can feel easier to swallow, and liquids suit people who struggle with either but often taste strongly of iron. Whatever you pick, work out the cost per day rather than the cost per pack, because strengths and pack sizes differ.
The arithmetic is simple: price divided by the number of daily servings. At the current “from” prices, our iron tablets with vitamin C, B12 and folic acid come to about 29p a day (£8.76 for 30 tablets), and the plain 14 mg ferrous fumarate tablet to about 25p a day (£7.50 for 30). Do the same sum for any product you compare, and remember to check that the elemental iron per daily dose is similar before you decide one is cheaper.
Label terms worth ignoring, and what to look for instead
Supplement labels are full of words that sound reassuring and tell you very little. Here is the checklist I use.
- Look for elemental iron per tablet: a clear milligram figure, ideally with the percentage of the reference value.
- Look for the form named: “ferrous fumarate”, “ferrous sulfate” and so on, not just “iron complex”.
- Look for a sensible daily dose: at or below 17 mg unless a GP has said otherwise.
- Look for vitamin C or advice on taking it with some: a simple, practical sign the maker understands absorption.
- Look for visible purity testing: a published Certificate of Analysis you can actually read.
- Ignore vague words: “high absorption”, “super strength” and “clinical” mean little without numbers behind them.
- Ignore very large mg numbers on the front: they may be the compound weight, not the iron.
- Ignore anything promising results: good iron tablets describe what they contain and what the nutrient contributes to, not what will happen to you.
Purity, vegan suitability and how we make ours
Our iron tablets are formulated in the UK, vegan and suitable for vegetarians, gluten-free, and free from artificial colours and needless additives. Every batch is tested for purity and heavy metals at our GMP-certified facility, and the Certificate of Analysis is published on the product page so you can read the results yourself. I think that is the right standard for a mineral, because you should be able to see what you are swallowing.
Everything on one panel: 14 mg of iron per tablet, with vitamin C, B12 and folic acid, and a long list of things left out.
Who should not self-supplement with iron
Iron is one to take because you need it, not just in case. The main groups who should take advice first are:
- Anyone who has not had a blood test: low iron has several possible causes, and the first step is finding which applies.
- Men and women after the menopause: lower reference intake, so unneeded iron is more likely to accumulate.
- People with haemochromatosis: the iron-overload condition. Do not take iron unless a specialist tells you to.
- People taking certain medicines: iron can interact with thyroid medication such as levothyroxine and some antibiotics, so leave several hours between them and check with your pharmacist.
- Pregnant or breastfeeding women: take iron on your midwife’s or GP’s advice.
If heavy periods are what is behind your question, our guide to iron and heavy periods covers testing and absorption in more depth.
Food sources, signs of low iron and when to see your GP
Food comes first. Haem iron in red meat, poultry and fish is absorbed fairly well. Non-haem iron in lentils, beans, tofu, dark leafy greens, fortified cereals, seeds and dried fruit is absorbed less readily, which is why pairing plant foods with a vitamin C source makes such a difference. If you eat little or no meat, building a squeeze of lemon or a few peppers into iron-rich meals is a habit worth keeping.
Common signs that your iron might be low include persistent tiredness, breathlessness on mild effort, pale skin and brittle nails. They overlap with many other things, so please take them as a reason for a blood test rather than a reason to start tablets. See your GP if you feel tired all the time, if you have heavy periods, or if symptoms are getting worse.
Side effects, dark stools and keeping iron away from children
Common side effects of oral iron include constipation, nausea, stomach discomfort and dark stools. Dark green or black stools are expected and harmless. Black, tarry or bloody stools, or severe stomach pain, are different and need prompt medical advice. Iron overdose is genuinely dangerous for small children, so store the pouch somewhere cool, dry and well out of reach.
What to realistically expect from iron tablets
Iron stores rebuild slowly, so patience matters more than the brand on the pouch. Many people need a couple of months of consistent, well-absorbed iron before a follow-up blood test shows much movement, and a deeper shortfall can take longer still. Nobody should expect to feel different overnight, and I would be wary of any product that implies you will. The sensible rhythm is to take your tablet consistently, keep the helpers and blockers in mind, and retest with your GP after the period they suggest.
It is also worth saying that some people simply do not get on with a particular form. If one iron product upsets you after a fair trial, trying a different form, a lower frequency such as alternate days, or a conversation with your pharmacist is far better than giving up on iron altogether.
A few cautions worth knowing
Do not take more than the label dose, and do not take high-dose iron for long periods without a blood test, because the body cannot easily get rid of surplus iron. Leave a gap between iron and thyroid medication, certain antibiotics, antacids and calcium supplements. If you are pregnant, breastfeeding, taking regular medication or managing a medical condition, check with your GP or pharmacist first. For the wider picture, our supplement guides hub brings all our guides together.
Frequently asked questions
What are the best iron tablets to buy in the UK?
The best iron tablet is the one that matches your need and that you will take consistently: a well-absorbed ferrous form, a clearly labelled elemental iron amount at or below 14 mg unless your GP has advised more, vitamin C alongside it, and purity testing you can see. Confirm you need iron with a GP blood test first.
What is the best form of iron to take?
There is no single winner. Ferrous salts such as fumarate, sulfate and gluconate are the most studied and are well absorbed; chelated forms such as bisglycinate are another option; and every form can upset some stomachs. What matters most is the elemental iron on the label, the dose and how you take it.
How much iron should I take a day?
The UK reference intake is 14.8 mg a day for women aged 19 to 49 and 8.7 mg for men and for women over 50. The NHS advises that 17 mg or less a day from supplements is unlikely to cause harm, and that you should only take more if a GP has advised it.
Should I take iron tablets on an empty stomach or with food?
Iron is absorbed best away from large meals, but taking it with a little non-dairy food is a sensible trade if it upsets your stomach. Keep tea, coffee, milk and calcium a couple of hours away from your tablet.
Can I take iron tablets without a blood test?
It is better not to. Low iron has several possible causes worth finding out about, and the body has no easy way to remove surplus iron. A GP blood test, including ferritin, shows whether iron is the right thing to take and for how long.
Is it normal for iron tablets to turn stools dark?
Yes, dark green or black stools are a common and harmless effect of oral iron. Black, tarry or bloody stools, or severe stomach pain, are different and need medical advice promptly.
Our pick for this guide
Ready for a simple one-a-day iron routine?
14 mg of iron per tablet (from 42 mg of ferrous fumarate) with 60 mg of vitamin C, 3 mcg of B12 and 200 mcg of folic acid, one tablet a day, vegan. A food supplement, not a replacement for medical advice.
From £8.76 · 30 tablets, one month
Shop Iron Tablets →Sources
- Cancelo-Hidalgo and colleagues, 2013, tolerability of different oral iron supplements, systematic review, DOI 10.1185/03007995.2012.761599 (PubMed 23252877)
- Tolkien and colleagues, 2015, ferrous sulphate supplementation and gastrointestinal side effects, systematic review and meta-analysis, DOI 10.1371/journal.pone.0117383 (PMC4336293)
- Stoffel and colleagues, 2017, iron absorption from oral iron given on consecutive versus alternate days and as single morning doses versus twice-daily split doses, DOI 10.1016/S2352-3026(17)30182-5 (PubMed 29032957)
- Teucher, Olivares and Cori, 2004, enhancers of iron absorption: ascorbic acid and other organic acids, DOI 10.1024/0300-9831.74.6.403
- Hurrell, Reddy and Cook, 1999, inhibition of non-haem iron absorption in man by polyphenolic-containing beverages, PubMed 10999016
- NHS, Vitamins and minerals: iron, nhs.uk
You can find more of our guides on the Pure Vitamins UK home page.
Warmly,
Dr. Miron, Founder of Pure Vitamins UK
This article is for general information and education. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle, and this is not medical advice. If you have symptoms or a health condition, speak to your GP or pharmacist.
