How long do you need to take iron supplements to see results?

Iron supplements boost low iron levels, helping you feel energised.
Written by
Sophie Overett
Reviewed by
Last updated on
July 7, 2023
min read
How Long Do Iron Tablets Take to Work? | Kin Fertility
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If you've ever had a routine blood test and been told you have low iron levels, you are definitely not alone. In fact, iron deficiency is extremely common, particularly among women.

Iron is an important mineral in helping the body function properly, with one of its most important roles being transporting oxygen in the blood and providing energy for daily life [1].

Many people who struggle to absorb enough of the mineral through diet alone will turn to supplements, which can be a great way to treat iron deficiency. But once you start taking an iron supplement, how do you know if it's working, and when should you expect to see or feel results?

Let's find out.

What are iron supplements, and why is iron important?

Before we start talking about supplements, it's important to understand what they are, why you might need them, and how much iron your body requires to function properly.

As we've mentioned, iron supports several functions and staples in the body including oxygen transport, red blood cells, enzymes and the immune system [1]. The amount of iron needed depends on numerous factors such as age and sex, but the average woman aged 19-50 will require around 19 milligrams per day,

We absorb the mineral through iron-rich foods such as meat (particularly red meat), legumes, green vegetables, tofu, some dairy products, bran foods and fortified breakfast cereals [2].

Increasing your iron intake through eating iron-rich foods might sound simple, but many people are actually not getting enough iron. This can be due to food insecurity, issues with absorption and storage, or due to shedding through sweat and blood loss.

Certain groups, such as menstruating women, have an increased chance of struggling with iron deficiency.

It is estimated that up to 5% of the Australian population has iron deficiency anaemia, a severe stage of deficiency wherein haemoglobin falls below the cutoff [1][3]. This occurs when iron stores are exhausted and the supply of iron to the tissues is compromised.

Symptoms of iron deficiency anaemia can include feeling tired, pale skin, dizziness, breathlessness, and poor immunity, which means being more vulnerable to infection and illness [1].

In children, iron deficiency anaemia can impact brain growth and development as well as contribute to behavioural problems, loss of appetite, lethargy, repeat infections, and not growing at the expected rate [1].

This is why it's important to check your levels (and those of your family) and consider taking an iron supplement to increase absorption if your body is not currently getting the amount it needs.

How do iron supplements work?

There are several forms of iron you can take to improve your levels, with the most common being oral iron supplements, which usually come in the form of iron pills, but can also be taken as a powder or chewable vitamin.

In addition to oral iron supplements, in some cases, a doctor might recommend an iron infusion, which is a treatment where iron is given intravenously and directly enters the bloodstream [4].

This can only be organised through a doctor and is generally recommended in cases where iron absorption is an issue, or where the patient's levels are in urgent need of increasing quickly.

A supplement can help boost low iron levels as they generally contain a higher amount of iron than the food you ingest through your diet.

The type of iron in the human body is called elemental iron, and the higher the amount of elemental iron in your iron pill, the better your iron absorption [5].

Many iron supplements also contain ferrous sulfate (10), which can come in iron tablets or liquid form [5]. Taking ferrous sulfate and elemental iron can help treat or prevent iron deficiency anaemia.

How long do iron tablets take to work?

If you've recently started a new supplement regime, you might be wondering how long it will take for your body to start absorbing iron and for your iron levels to increase.

A course of supplements to treat iron deficiency anaemia will often last for several months, but it is recommended to check in with your doctor 1-4 weeks after you start supplementation, to make sure your iron absorption is improving [6][3].

Results will vary from person to person, so some people will see their iron stores improve within the first week of taking an iron supplement, but for others, it can take several weeks.

If you do not experience an improvement in this time, it could be an indication that there is an issue with absorption or that the supplements you are taking are not quite right for you, and you may need to discuss alternatives with your doctor.

How do I know if the iron tablets are working?

If you previously felt some of the symptoms we've mentioned, like fatigue or dizziness, and these issues begin to improve, that is a good sign your supplement is working.

This kind of biological sign can sometimes be unclear or misleading though, so it is generally best not to rely on symptoms alone to judge the efficacy of your supplements!

The most reliable way to check your iron absorption and whether your iron supplements are working is by visiting your doctor for a follow-up test to check whether your iron levels have improved.

If your iron supplement appears to be working, you should still continue taking it for several months to build up reserves and prevent iron deficiency anaemia from returning.

Are there any potential side effects of taking iron supplements?

There are a number of potential side effects to be aware of when taking iron supplements [1]. The most common are changes in your bowel movements and darker stools, which are not generally a cause for concern.

Other common side effects which can be uncomfortable include nausea, stomach cramps, constipation or diarrhoea.

If any of these side effects or symptoms are causing significant pain, please contact your doctor to make sure your iron supplement is not reacting badly with another medication or causing you serious harm.

Taking more iron than you need can actually be toxic for your body (especially for children), and taking iron tablets if you don't really need them can interfere with your absorption of other vitamins and minerals [7].

Some people also have a condition called Haemochromatosis, which causes the body to actually absorb an unusually high amount of iron from food and can cause a toxic build-up in the body if left untreated [7]. People with this condition should actually reduce their iron intake and avoid both vitamin C supplements and iron supplements.

What is the best way to take iron supplements for the best iron absorption?

One thing to be aware of when taking iron supplements (or any type of vitamin supplements) is whether you are taking them at the right time or in the right way for optimal absorption.

It is generally recommended to take iron supplements on an empty stomach, as this is when they are more easily absorbed. However, for some people this can cause nausea, so you might want to consider taking your iron supplement alongside your breakfast.

Vitamin C supplements, or foods rich in vitamin C such as orange juice, can help your body to absorb iron supplements.

Kin's daily Iron Support supplement is designed to relieve fatigue from inadequate iron intake and low iron levels in pregnancy.

On the other hand, some food items such as milk and calcium, tannins (found in tea, coffee and wine) and whole grains such as bran, can actually hinder the iron absorbed [1].

If you suspect you may have iron deficiency anaemia or issues with iron absorption, it is best to speak with a doctor and get your levels checked.

A new iron supplement regime should be started under the supervision and recommendation of a medical professional to ensure you are taking the best iron supplements for your needs and aren't overdoing it, especially if you are pregnant or breastfeeding.

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