The best iron supplements to take for sensitive stomachs

If you suffer from a sensitive stomach, finding an iron supplement that does not upset your stomach is often a challenge. It is important to find the right iron supplements that provide the best iron absorption for sensitive stomachs…

Woman suffering from menstrual cramps

Here we will break down the types of iron supplements and what you need to know when finding the best supplement for your sensitive stomach. We will cover the following:

Types of iron supplements

There are several different ways to increase your iron intake through supplementation. Traditionally there are:

  • Oral iron
  • Low dose oral iron – available over the counter
  • High dose oral iron – prescription only
  • Intravenous infusion – undertaken in the hospital while being monitored.

The type of iron you are recommended to take will depend on any symptoms you experience, taking into account your diet and/or blood test results. There is not necessarily the same fix for everyone. Low iron is common, with 1 in 4 women having low iron.¹

Oral iron supplements

If your blood test results reveal you have low iron, often a very high dose of iron will be prescribed orally to balance out your levels quickly. However, this can be harsh on your stomach and isn’t always well absorbed, causing some unpleasant side effects, especially for sensitive stomachs.

This often results in 50% of people stopping their prescribed high-dose iron supplements.² These side effects commonly include:

  • Nausea
  • Stomach Cramps
  • Constipation
  • Diarrhoea
  • Black Stools

If the dose is lower you are less likely to experience symptoms, yet very low doses may not replenish levels adequately or quickly enough. Finding an iron supplement that works well with sensitive stomachs and releases iron into your body without side effects is important. Active Iron is an iron supplement that is clinically proven to increase iron levels by up to 94%.³ 

Active Iron is gentle on the stomach, helping to avoid gut irritation.

Liquid iron supplements

One option for people with sensitive stomachs is liquid iron supplements, where the liquid is targeted to release iron quickly into your body. Often these doses are very low, ranging from 2mg – 5mg—however, the recommended daily intake is 14mg. Some side effects of taking liquid iron supplements include teeth staining, a horrible metallic taste that’s difficult to overcome, a burning sensation in the esophagus, diarrhoea, and nausea. Unlike liquid iron supplements, Active Iron is designed to target the body’s site of iron absorption, where it is best absorbed, while still reducing the likelihood of side effects. That’s why it is one of the best iron supplements for sensitive stomachs.

Why do some iron supplements upset your stomach?

Many iron supplements upset your stomach because they oxidize in the gut and as a result, are poorly absorbed (typically, just 10% is absorbed). This oxidation and poor absorption cause gastrointestinal side effects such as nausea and constipation in 8/10 people.⁴ The higher dose of iron in supplements, the more likely symptoms are to present. It is important to find a high-quality supplement that does not cause these side effects and discomfort. Active Iron offers a great solution to help avoid gut irritation from iron. Unlike other oral iron, its whey protein formula protects the iron from oxidation, allowing for better absorption⁵ of iron sulfate.

How to take iron supplements and not upset your stomach

Often traditional iron supplements come with advice on how to take them in the best way to not upset your stomach. 

Taking your iron supplement with fruit juice can help to improve the absorption of iron in the supplement. 

Taking iron supplements alongside food and avoiding taking on an empty stomach, can can help to make the iron more gentle on the stomach.

Usually, if you do take supplements on an empty stomach, it can really upset your stomach. Active Iron was created to avoid this need and make it easier to take iron supplements at any time of day, even for the most sensitive stomachs.

Iron supplements that are easy on your stomach

Traditionally, iron supplements were very harsh on the stomach and caused many stomach complaints, resulting in lapsed usage.

Sometimes the symptoms of supplementation are worse than those of low iron, so many people choose to avoid the symptoms that come with taking high-dose iron and opt to live with low iron levels instead. This can cause chronic fatigue, weakness, and breathlessness, to name a few. To mitigate this, liquid iron supplements were introduced as a better alternative for those with sensitive stomachs and difficulty completing prescription recommendations.

However, liquid iron has its issues and is not always well absorbed. It can have additional side effects on top of those commonly found with traditional iron supplements, along with the possibility of staining your teeth, which one would obviously want to avoid!

Active Iron was created to solve the issues of oral iron supplements and give users the boost of iron they need while helping to avoid uncomfortable side effects. Active Iron is less likely to cause stomach upset than traditional iron supplements, and delivers the right amount of iron needed³.

An iron supplement for sensitive stomachs – Active Iron

Active Iron’s iron supplements are designed for sensitive stomachs and to help prevent side effects, e.g. feeling sick, nauseous, and constipated. Active Iron’s ground-breaking protein formula targets the body’s natural site of iron absorption, the DMT-1. This helps to increase the amount of iron absorbed. As a result, Active Iron is less likely to cause gut irritation than other iron supplements and has been clinically proven to increase iron stores by 94%³. These results remain indifferent regardless of dosage, unlike many iron supplements, where a higher dose means more side effects. Participants also reported higher energy levels and a reduction in tiredness and fatigue.

Where to buy iron supplements that are easy on your stomach?

As mentioned, the best option for sensitive stomachs is Active Iron, and it is important to maintain a healthy iron level, especially in women, where low iron levels are common.

In the USA

In the USA, Active Iron is available here.

How to make sure iron supplements don’t upset your stomach

The answer is simple, try Active Iron. 

Active Iron is the only iron supplement that is clinically proven to increase iron levels whilst being gentle on your stomach. In fact, Active Iron is so gentle that you can take it on an empty stomach. 

Gone are the days when you need to worry about an upset stomach when taking iron supplements!

Active Iron High Potency

Active Iron High Potency is clinically proven to help prevent gut irritation and increase iron levels by 94%², meaning it is kind on your stomach yet strong on absorption.

Active Iron High Potency Review

“As a busy full-time working mom, sonographer, daughter, entrepreneur, sometimes my diet lacks things that help support my iron levels. So glad I was able to try these and fall in love with the benefits!!” -Kimberly H

Review source

Active Iron For Women

Active Iron for Women Review

“This is the first iron supplement that delivered what was promised.
Not even a hint of stomach upset and including the multi is ingenious.
I don’t dread lab work since taking this daily supplement.” -Amazon Customer

Review source

Iron Supplements for sensitive stomachs – FAQs:

Why is Active Iron the best supplement for sensitive stomachs?

Active Iron is the best supplement for sensitive stomachs as its non-constipating formula is clinically proven to help avoid gut irritation. Active Iron is gentle enough to take on an empty stomach. 

What is the best iron supplement for avoiding constipation?

Active Iron is the best iron supplement for avoiding constipation as it is clinically proven to help avoid common gastrointestinal side effects, including constipation. 

Can you recommend an iron supplement that doesn’t cause nausea?

We recommend Active Iron as the best iron supplement to avoid nausea as it is clinically proven to help avoid common iron side effects such as nausea. 

What is the best liquid iron supplement for sensitive stomach?

Most liquid iron supplements contain a much lower dose of iron which is why they can avoid these common side effects. Although this is a great benefit, they often do not provide sufficient iron to increase iron levels with some only containing 5mg iron per serving.

Active Iron offers a great solution for those looking for an iron supplement suitable for a sensitive stomach. Active Iron is clinically proven to increase iron levels by 94% and is gentle on the stomach, helping to prevent side effects such as nausea and constipation. 

Are Active Iron’s supplements easy on your stomach?

Yes, Active Iron is clinically proven to cause less gut irritation compared to other iron supplements, making it easy on your stomach. 

What is the best iron supplement for IBS?

If you suffer with IBS it is important to check the ingredients and formulation of iron supplements. Active Iron may be the best iron supplement for IBS as it helps prevent gastrointestinal side effects such as constipation and diarrhea, which are common IBS symptoms. 


¹NICE. Anaemia – iron deficiency. September 2018

²Tolkien et al. PLoS ONE 2015; 10(2): e0117383. doi:10.1371/journal.pone.01173832015.

³Ledwidge et al. 2021, Data on file. doi:

⁴Pereira D et al BMC Gastroenterol 2014 Jun 4;14:103. doi: 10.1186/1471-230X-14-103

⁵Wang et al. 2017, Acta Haematologica, 138: 223-232.

Dr Kiran Rahim

Dr Kiran Rahim


Dr Kiran is a NHS Doctor, specializing in baby, child and adolescent health. She has worked across many London Hospitals and uses her own experience as a mother and south Asian woman to talk about key issues relating to women and child health.

Read more about our expert here.