Side Effects of Taking Iron Supplements

If you're thinking about taking iron supplements, it's important to know that they can come with a variety of side effects.

From mild tummy troubles to more serious concerns like iron overdose, this article aims to give you some things to consider when supplementing with iron.

What Are the Side Effects of Taking Iron Supplements

Do Iron Supplements Have Side Effects?

Yes. Traditional iron supplements often come with a range of negative side effects. These can include gastrointestinal issues, as well as less common problems like metallic taste, skin reactions, and allergic reactions.

Serious side effects

The serious side effects of iron supplementation are relatively rare but can include:

  1. Gastrointestinal Issues: High doses of iron may cause stomach pain,  nausea, vomiting and, in some severe cases, it can lead to gastrointestinal bleeding or ulceration.

  2. Iron Overload: Chronic iron overload, or hemochromatosis, can occur when excess iron is stored in the body. This can lead to serious complications.

  3. Allergic Reactions: Although uncommon, some individuals may experience allergic reactions to iron supplements, which can manifest as skin rashes, hives, or worse.

  4. Organ Damage: Excessive iron intake over a long period can lead to damage in organs like the liver and heart.

Common Gastro-Intestinal Side Effects of Iron

The gastrointestinal system is often the first to show signs when you begin taking iron supplements. The side effects you may experience arise because iron ions can be irritating to the gastrointestinal tract lining.

The symptoms are generally mild and may subside as your body gets used to the supplement. However, they can be uncomfortable and inconvenient, particularly if you're not prepared for them. In some cases, they simply do not recede either. This is why it is best to consult a qualified health professional to help guide you.

Upset Stomach 

Some people experience a general sense of stomach discomfort or upset when taking iron supplements. This can manifest as cramps, bloating, or a feeling of fullness. The cause is often the same as that of nausea—interaction with serotonin receptors in the gut. Taking the supplement with food or switching to a slow-release formulation can often alleviate these symptoms.

These gastrointestinal side effects are among the most commonly reported and can often be managed with simple lifestyle changes. However, persistent or severe symptoms should be evaluated by a healthcare professional.

Dark Stools

Another commonly observed side effect of taking iron supplements is darkened stools. This change in colour is generally not a cause for alarm and is actually a direct result of the iron being processed by your body.

When you ingest iron supplements, the iron combines with gastric acids in the stomach. This mixture is then passed through the digestive system, where it may react with other compounds and enzymes. These reactions can result in the formation of a dark, often blackish, insoluble iron compound called ferric sulfide. This compound is what gives the stool its darkened colour.

While dark stools might be unsettling if you're not expecting them, understanding that this is a common reaction to iron supplements can be reassuring. Nonetheless, if the darkened stool is accompanied by other symptoms or persists for an extended period, consultation with a healthcare professional is advisable.

Metallic Taste

One lesser-known but still common side effect of taking iron supplements is experiencing a metallic taste in the mouth. This occurs due to the presence of iron ions interacting with taste receptors on the tongue. These receptors are sensitive to various minerals and compounds, and iron happens to be one that can cause a noticeable change in taste perception.

The metallic taste is generally short-lived and tends to dissipate as the body processes the iron. While it's not harmful, many people find it off-putting or unpleasant. If you find the metallic taste particularly bothersome, some find relief by taking the supplement with citrus juice, which not only masks the taste but can also aid in iron absorption.

Skin Reactions

Some individuals may experience skin reactions when taking iron supplements. These can manifest as rashes, itchiness, or even more severe allergic reactions in rare cases. The exact mechanism behind these skin reactions is not entirely understood but is likely related to an immune response.

The body's immune system can sometimes identify the iron ions as foreign bodies, triggering an allergic response. This could lead to the release of  substances that cause the allergic symptoms such as rashes and itchiness. If you experience any severe skin reactions, it's crucial to discontinue the supplement and seek immediate medical advice.

Allergic Reactions

Though relatively rare, some people may experience allergic reactions to iron supplements. Symptoms can include hives, difficulty breathing, and swelling of the face, lips, tongue, or throat. These reactions occur when the immune system mistakenly identifies the iron supplement as a harmful substance and releases chemicals to fight it off.

An allergic reaction to an iron supplement is a medical emergency requiring immediate attention. If you suspect you're experiencing an allergic reaction, discontinue use of the supplement and seek emergency medical care. It's crucial to identify this allergic sensitivity as early as possible to avoid more severe complications.


Ironically, some people report feeling fatigued or unusually tired when they start taking iron supplements. This may seem counterintuitive.

The reason for this paradoxical effect isn't entirely clear but may be related to the body's adjustment period to increased iron levels. Iron plays a complex role in the body's metabolic pathways, and introducing additional iron might temporarily disrupt these processes before a new equilibrium is reached. If you experience persistent fatigue while taking iron supplements, it's important to consult a healthcare professional for a comprehensive evaluation.


Headaches are another side effect that some individuals experience when taking iron supplements. The exact mechanism behind this is not fully understood, but it is hypothesized that it may be related to changes in blood pressure or alterations in blood flow. Iron plays a role in the formation of haemoglobin, the molecule in red blood cells that carries oxygen. Changes in haemoglobin levels could potentially affect blood flow to the brain, leading to headaches.

It's also possible that headaches are a result of the body adjusting to increased iron levels, especially if supplementation is started at a high dosage. If headaches are persistent or severe, reducing the dosage under medical supervision or discontinuing the supplement may be necessary. Consult a healthcare professional for persistent symptoms.


Dizziness is a less common but noteworthy side effect of iron supplementation. Similar to headaches, the cause of dizziness is not entirely clear but may be linked to changes in blood pressure or blood oxygen levels. As iron supplements increase haemoglobin levels, this could temporarily alter the body's equilibrium, leading to sensations of dizziness or instability.

If you experience dizziness, it's crucial to exercise caution, especially when driving or operating heavy machinery. As with other side effects, persistent or severe dizziness should be evaluated by a healthcare professional to rule out other potential causes and to adjust the iron supplementation regimen if needed.

Seeking an Iron Supplement with Fewer Side Effects?

Many people experience side effects with traditional iron supplements, and finding another option may be a priority for you. Nano Iron, because of its purity and incredibly small particle size gives us a new form of iron that is highly absorbable. 

Nano Iron's innovative formulation is crafted to enhance absorption efficiency, potentially offering a more comfortable experience by reducing the direct impact on the digestive system. This approach aims to provide the benefits of iron supplementation while aiming to lessen the typical discomforts.

However, it's important to remember that individual experiences can vary, and what works for one person may not work for another. Consulting with a healthcare professional is the best way to determine if Nano Iron is a suitable choice for your specific health needs and supplementation goals.

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Do Side Effects of Iron Supplements Go Away?

Contrary to common belief, some side effects may not necessarily go away over time and can persist during the course of iron supplementation.

While some individuals find that their bodies adjust to the iron supplement, leading to a reduction in side effects, this is not the case for everyone. Gastrointestinal issues can persist for as long as you are taking the supplement. This is because the iron ions in the supplement interact with enzymes and other substances in the gastrointestinal tract, leading to continued discomfort.

In some cases, adjusting the type or dosage of iron supplement may alleviate some of these persistent side effects. For example, some individuals find relief by switching to a slow-release or lower-dose formulation. However, these modifications should only be made under medical supervision.

Which Iron Supplement is Better Tolerated

For those in search of an iron supplement that is better tolerated, Nano Iron represents a promising option. 

Nano Iron features iron particles that are ultra-small, ranging between 0.5 and 7 nanometers, and are suspended in purified (energised) water. This notably small size necessarily facilitate a more direct absorption of the iron particles, potentially circumventing the digestive system. This innovative approach may mitigate common gastrointestinal issues linked with many iron supplements.

Moreover, Nano Iron is developed with the goal of achieving pure iron atoms that are fully absorbable. This suggests that the body is capable of absorbing and utilizing all the iron it provides. Nano Iron also offers dosage flexibility, allowing for adjustments according to individual needs which should be done under the guidance of a qualified health professional.

It is essential to consult with a healthcare professional before starting any new supplement regimen. They can offer personalized advice and help determine if Nano Iron is suitable for your specific health requirements or not.

FAQS on Iron Side Effects

Q: Can iron supplements affect my teeth?
A: Yes, some people have reported that liquid iron supplements can stain teeth. This is generally more common with ferrous sulfate solutions. The staining can usually be removed by a dentist, but it's advisable to consult healthcare professionals for alternatives if this side effect is a concern.

Q: Do iron supplements interfere with other medications I might be taking?
A: Iron supplements can interact with certain medications. This can either make your medication less effective or increase its side effects. You must always consult your healthcare provider when adding an iron supplement to your regimen if you're already on other medications.

Q: Can iron supplements affect my menstrual cycle?
A: There is limited evidence to suggest that iron supplements have a direct impact on the menstrual cycle. However, iron supplementation is often recommended for menstruating individuals to replenish lost iron.

Q: Are there side effects related to long-term storage of iron supplements?
A: Iron supplements have a shelf life. Using expired supplements can lead to reduced effectiveness and a potential increase in side effects, such as gastrointestinal discomfort.

Q: Can iron supplements cause weight gain?
A: There's no scientific evidence to suggest that iron supplements cause weight gain. However, if you're iron-deficient, proper supplementation may maintain a correct balance.

Q: Are the side effects of iron supplements different for children and adults?
A: Children are more sensitive to iron and are at a higher risk for iron overdose, which can be fatal in severe cases. While some side effects might be common across age groups, the severity and risk factors can differ. Always consult a paediatrician before giving iron supplements to children.

Q: Can iron supplements cause joint pain?
A: Joint pain is not a commonly reported side effect of iron supplements. However, excessive iron storage can lead to joint pain among other symptoms. If you experience unexplained joint pain, consult your healthcare provider.

Q: Is it possible for iron supplements to cause a rash?
A: While rare, some people may experience skin rashes as an allergic reaction to iron supplements. If you notice a rash after starting an iron supplement, discontinue use and consult a healthcare professional.

Q: Do iron supplements have an effect on hair and nails?

A: Iron deficiency is linked to hair loss and brittle nails. While not a side effect, proper iron supplementation may lead to improvements in hair and nail health for those who are deficient.