Iron - Side Effects

What Are "Star" Ratings?

a7_3star Reliable and relatively consistent scientific data showing a substantial health benefit.

a7_2star Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

a7_1star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

This supplement has been used in connection with the following health conditions:

Used for	Amount	Why
Anemia and Iron Deficiency	If deficient: 100 mg daily for up to one year under medical supervision	Taking iron may help prevent and treat anemia; ask your doctor if it’s right for you. Deficiencies of iron, vitamin B12, and folic acid are the most common nutritional causes of anemia.
Anemia and Iron Deficiency If deficient: 100 mg daily for up to one year under medical supervision Deficiencies of iron, vitamin B12, and folic acid are the most common nutritional causes of anemia.¹ Although rare, severe deficiencies of several other vitamins and minerals, including vitamin A,² ^{, 3} vitamin B2,⁴ vitamin B6,⁵ ^{, 6} vitamin C,⁷ and copper,⁸ ^{, 9} can also cause anemia by various mechanisms. Rare genetic disorders can cause anemias that may improve with large amounts of supplements such as vitamin B1.¹⁰ ^{, 11}

Used for	Amount	Why
Depression and Iron Deficiency	See a doctor for evaluation	A lack of iron can make depression worse; check with a doctor to find out if you are iron deficient.
Depression and Iron Deficiency See a doctor for evaluation Iron deficiency is known to affect mood and can exacerbate depression, but it can only be diagnosed and treated by a doctor. While iron deficiency is easy to fix with iron supplements, people who have not been diagnosed with iron deficiency should not supplement iron.

Used for	Amount	Why
Iron-Deficiency Anemia	Consult a qualified healthcare practitioner	Supplementing with iron is essential to treating iron deficiency.
Iron-Deficiency Anemia Consult a qualified healthcare practitioner Caution: People should not supplement with iron unless diagnosed with iron deficiency, because taking iron when it isn’t needed has no benefit and may be harmful. Before iron deficiency can be treated, it must be diagnosed and the cause must be found by a doctor. In addition to addressing the cause (e.g., avoiding aspirin, treating a bleeding ulcer, etc.), supplementation with iron is the primary way to resolve iron-deficiency anemia. If a doctor diagnoses iron deficiency, iron supplementation is essential. Though some doctors use higher amounts, a common daily dose for adults is 100 mg per day. Even though symptoms of deficiency should disappear much sooner, iron deficient people usually need to keep supplementing with iron for six months to one year until the ferritin test is completely normal. Even after taking enough iron to overcome the deficiency, some people with recurrent iron deficiency—particularly some premenopausal women—need to continue to supplement with smaller levels of iron, such as the 18 mg present in most multivitamin-mineral supplements. This need for continual iron supplementation even after deficiency has been overcome should be determined by a doctor. Learn More

Used for	Amount	Why
Menorrhagia and Iron Deficiency	100 to 200 mg daily under medical supervision if deficient	Supplementing with iron decreases excess menstrual blood loss in iron-deficient women who have no other underlying cause for their condition.
Menorrhagia and Iron Deficiency 100 to 200 mg daily under medical supervision if deficient Since blood is rich in iron, excessive blood loss can lead to iron depletion. Iron deficiency can be identified with simple blood tests. If an iron deficiency is diagnosed, many doctors recommend 100–200 mg of iron per day, although recommendations vary widely. The relationship between iron deficiency and menorrhagia is complicated. Not only can the condition lead to iron deficiency, but iron deficiency can lead to or aggravate menorrhagia by reducing the capacity of the uterus to stop the bleeding. Supplementing with iron decreases excess menstrual blood loss in iron-deficient women who have no other underlying cause for their condition.¹² ^{, 13} However, iron supplements should be taken only by people who have, or are at risk of developing, iron deficiency.

Used for	Amount	Why
Athletic Performance and Iron Deficiency	Consult a qualified healthcare practitioner	Iron is a component of hemoglobin, which transports oxygen to muscle cells. In cases of iron deficiency, taking iron may restore levels and improve athletic performance.
Athletic Performance and Iron Deficiency Consult a qualified healthcare practitioner Iron is important for an athlete because it is a component of hemoglobin, which transports oxygen to muscle cells. Some athletes, especially women, do not get enough iron in their diet. In addition, for reasons that are unclear, endurance athletes, such as marathon runners, frequently have low body-iron levels.¹⁴^{, 15}^{, 16} However, anemia in athletes is often not due to iron deficiency and may be a normal adaptation to the stress of exercise.¹⁷ Supplementing with iron is usually unwise unless a deficiency has been diagnosed. People who experience undue fatigue (an early warning sign of iron deficiency) should have their iron status evaluated by a doctor. Athletes who are found to be iron deficient by a physician are typically given 100 mg per day until blood tests indicate they are no longer deficient. Supplementing iron-deficient athletes with 100 to 200 mg per day of iron increased aerobic exercise performance in some,¹⁸^{, 19}^{, 20} though not all,²¹^{, 22} double-blind studies. A recent double-blind trial found that iron-deficient women who took 20 mg per day of iron for six weeks were able to perform knee strength exercises for a longer time without muscle fatigue compared with those taking a placebo.²³

Used for	Amount	Why
Attention Deficit–Hyperactivity Disorder and Iron Deficiency	Consult a qualified healthcare practitioner	In one study, iron levels were significantly lower in a group of children with ADHD than in healthy children. In the case of iron deficiency, supplementing with the mineral may improve behavior.
Attention Deficit–Hyperactivity Disorder and Iron Deficiency Consult a qualified healthcare practitioner Iron status, as measured by the serum ferritin concentration, was significantly lower in a group of children with ADHD than in healthy children. Ferritin levels were below normal in 84% of the children with ADHD, compared with 18% of the healthy children.²⁴ Since iron deficiency can adversely affect mood and cognitive function, iron status should be assessed in children with ADHD, and those who are deficient should receive an iron supplement. In a case report, a young boy with both ADHD and iron deficiency showed considerable improvement in behavior after receiving an iron supplement.²⁵ Iron supplementation was also beneficial in a double-blind study of children with ADHD and iron deficiency.²⁶

Used for	Amount	Why
Breast-Feeding Support and Iron Deficiency	Consult a qualified healthcare practitioner	Iron may be required for infants with low iron stores or anemia.
Breast-Feeding Support and Iron Deficiency Consult a qualified healthcare practitioner If a doctor diagnoses iron deficiency, iron supplementation is essential. Though some doctors use higher amounts, a common daily dose for adults is 100 mg per day. Even though symptoms of deficiency should disappear much sooner, iron deficient people usually need to keep supplementing with iron for six months to one year until the ferritin test is completely normal. Even after taking enough iron to overcome the deficiency, some people with recurrent iron deficiency—particularly some premenopausal women—need to continue to supplement with smaller levels of iron, such as the 18 mg present in most multivitamin-mineral supplements. This need for continual iron supplementation even after deficiency has been overcome should be determined by a doctor.

Used for	Amount	Why
Canker Sores and Iron Deficiency	Consult with your doctor	Talk to your doctor to see if your recurrent canker sores might be related to iron deficiency.
Canker Sores and Iron Deficiency Consult with your doctor Several preliminary studies,²⁷ ^{, 28} ^{, 29} ^{, 30} though not all,³¹ have found a surprisingly high incidence of iron and B vitamin deficiency among people with recurrent canker sores. Treating these deficiencies has been reported in preliminary³² ^{, 33} and controlled³⁴ studies to reduce or eliminate canker sore recurrences in most cases. Supplementing daily with B vitamins—300 mg vitamin B1, 20 mg vitamin B2, and 150 mg vitamin B6—has been reported to provide some people with relief.³⁵ Thiamine (B1) deficiency specifically has been linked to an increased risk of canker sores.³⁶ The right supplemental level of iron requires diagnosis of an iron deficiency by a healthcare professional using lab tests.

Used for	Amount	Why
Celiac Disease and Iron Deficiency	Consult a qualified healthcare practitioner	The malabsorption that occurs in celiac disease can lead to multiple nutritional deficiencies. Supplementing with iron may correct a deficiency.
Celiac Disease and Iron Deficiency Consult a qualified healthcare practitioner The malabsorption that occurs in celiac disease can lead to multiple nutritional deficiencies. The most common nutritional problems in people with celiac disease include deficiencies of essential fatty acids, iron, vitamin D, vitamin K, calcium, magnesium, and folic acid.³⁷ Zinc malabsorption also occurs frequently in celiac disease³⁸ and may result in zinc deficiency, even in people who are otherwise in remission.³⁹ People with newly diagnosed celiac disease should be assessed for nutritional deficiencies by a doctor. Celiac patients who have not yet completely recovered should supplement with a high-potency multivitamin-mineral. Some patients may require even higher amounts of some of these vitamins and minerals—an issue that should be discussed with their healthcare practitioner. Evidence of a nutrient deficiency in a celiac patient is a clear indication for supplementation with that nutrient. After commencement of a gluten-free diet, overall nutritional status gradually improves. However, deficiencies of some nutrients may persist, even in people who are strictly avoiding gluten. For example, magnesium deficiency was found in 8 of 23 adults with celiac disease who had been following a gluten-free diet and were symptom-free. When these adults were supplemented with magnesium for two years, their bone mineral density increased significantly.⁴⁰

Used for	Amount	Why
Night Blindness and Iron Deficiency	30 mg of iron and 6 mg of riboflavin per day	If a person has deficiencies of iron and riboflavin, supplementing with these nutrients may increase the benefits of vitamin A.
Night Blindness and Iron Deficiency 30 mg of iron and 6 mg of riboflavin per day In a study of women in Nepal, where there is a high prevalence of iron and riboflavin deficiencies, supplementation with 30 mg per day of iron and 6 mg per day of riboflavin for six weeks enhanced the effectiveness of vitamin A in the treatment of night blindness.⁴¹ It is not known whether these nutrients would be helpful for night blindness in people who are not deficient.

Used for	Amount	Why
Pre- and Post-Surgery Health	Consult a qualified healthcare practitioner	Iron supplementation prior to surgery was found in one trial to reduce the need for postoperative blood transfusions.
Pre- and Post-Surgery Health Consult a qualified healthcare practitioner One preliminary study found iron levels to be reduced after both minor and major surgeries, and iron supplementation prior to surgery was not able to prevent this reduction.⁴² A controlled trial found that intravenous iron was more effective than oral iron for restoring normal iron levels after spinal surgery in children.⁴³ One animal study reported that supplementation with fructo-oligosaccharides (FOS) improved the absorption of iron and prevented anemia after surgery,⁴⁴ but no human trials have been done to confirm this finding. Some researchers speculate that iron deficiency after a trauma such as surgery is an important mechanism for avoiding infection, and they suggest that iron supplements should not be given after surgery.⁴⁵ Patients who have undergone major surgery frequently need blood transfusions to replace blood lost during the procedure. Studies have found that 18 to 21% of surgery patients were anemic prior to surgery,⁴⁶ ^{, 47} and these anemic patients required more blood after surgery than did non-anemic surgery patients. Supplementation with iron prior to surgery was found in a controlled trial to reduce the need for blood transfusions, whether or not iron deficiency was present.⁴⁸ Iron supplements (99 mg per day) given before and for two months after joint surgery in another controlled trial improved blood values but did not change the length of hospitalization or the risk of post-operative fever.⁴⁹ Pre-operative iron supplementation in combination with a medication that stimulates red blood cell production in the bone marrow is considered by some doctors to be an effective way to minimize the need for post-operative blood transfusions.⁵⁰ Learn More

Used for	Amount	Why
Pregnancy and Postpartum Support	Consult a qualified healthcare practitioner	Iron requirements increase during pregnancy, making iron deficiency in pregnancy quite common. Supplementation may help prevent a deficiency.
Pregnancy and Postpartum Support Consult a qualified healthcare practitioner Iron requirements increase during pregnancy, making iron deficiency in pregnancy quite common.⁵¹ Iron supplement use in the United States is estimated at 85% during pregnancy, with most women taking supplements three or more times per week for three months.⁵² Pregnant women with a documented iron deficiency need doctor-supervised treatment. In one study, 65% of women who were not given extra iron developed iron deficiency during pregnancy, compared with none who received an iron supplement.⁵³ However, there is a clear increase in reported side effects with increasing supplement amounts of iron, especially iron sulfate.⁵⁴^{, 55} Supplementation with large amounts of iron has also been shown to reduce blood levels of zinc.⁵⁶ Although the significance of that finding is not clear, low blood levels of zinc have been associated with an increased risk of complications in both the mother and fetus.⁵⁷ Iron supplementation was associated in one study with an increased incidence of birth defects,⁵⁸ possibly as a result of an iron-induced deficiency of zinc. Although additional research needs to be done, the evidence suggests that women who are supplementing with iron during pregnancy should also take a multivitamin-mineral formula that contains adequate amounts of zinc. To be on the safe side, pregnant women should discuss their supplement program with a doctor. Learn More

Used for	Amount	Why
Restless Legs Syndrome and Iron Deficiency	Consult a qualified healthcare practitioner	When iron deficiency is the cause of restless leg syndrome, supplementing with iron may reduce the severity of the symptoms.
Restless Legs Syndrome and Iron Deficiency Consult a qualified healthcare practitioner Mild iron deficiency is common, even in people who are not anemic. When iron deficiency is the cause of RLS, supplementation with iron has been reported to reduce the severity of the symptoms. In one trial, 74 mg of iron taken three times a day for two months, reduced symptoms in people with RLS.⁵⁹ In people who are not deficient in iron, iron supplementation has been reported to not help reduce symptoms of RLS.⁶⁰ Most people are not iron deficient, and taking too much can lead to adverse effects. Therefore, iron supplements should only be taken by people who have a diagnosed deficiency.

Used for	Amount	Why
Alzheimer’s Disease (Coenzyme Q10, Vitamin B6)	Refer to label instructions	A combination of coenzyme Q10, iron (sodium ferrous citrate), and vitamin B6 may improve mental status in people with Alzheimer’s disease.
Alzheimer’s Disease In a preliminary report, two people with a hereditary form of Alzheimer’s disease received daily: coenzyme Q10 (60 mg), iron (150 mg of sodium ferrous citrate), and vitamin B6 (180 mg). Mental status improved in both patients, and one became almost normal after six months.⁶¹ Learn More

Used for	Amount	Why
Dermatitis Herpetiformis and Iron Deficiency	Refer to label instructions	Talk to your doctor to see if supplementing with iron can counteract the nutrient deficiency that often occurs as a result of malabsorption.
Dermatitis Herpetiformis and Iron Deficiency People with DH frequently have mild malabsorption (difficulty absorbing certain nutrients) associated with low stomach acid (hypochlorhydria) and inflammation of the stomach lining (atrophic gastritis).⁶² Mild malabsorption may result in anemia⁶³ and nutritional deficiencies of iron, folic acid,⁶⁴ ^{, 65} vitamin B12,⁶⁶ ^{, 67} and zinc.⁶⁸ ^{, 69} ^{, 70} More severe malabsorption may result in loss of bone mass.⁷¹ Additional subtle deficiencies of vitamins and minerals are possible, but have not been investigated. Therefore, some doctors recommend people with DH have their nutritional status checked regularly with laboratory studies. These doctors may also recommend multivitamin-mineral supplements and, to correct the low stomach acid, supplemental betaine HCl (a source of hydrochloric acid).

Used for	Amount	Why
Female Infertility and Iron Deficiency	Refer to label instructions	Even subtle iron deficiencies have been tentatively linked to infertility. Women who are infertile should consult a doctor to rule out the possibility of iron deficiency
Female Infertility and Iron Deficiency In preliminary research, even a subtle deficiency of iron has been tentatively linked to infertility.⁷² Women who are infertile should consult a doctor to rule out the possibility of iron deficiency.

Used for	Amount	Why
HIV and AIDS Support	Refer to label instructions	Iron deficiency is often present in HIV-positive children. Supplementing with it, under a doctor's supervision, may support immune function.
HIV and AIDS Support Iron deficiency is often present in HIV-positive children.⁷³ While iron is necessary for normal immune function, iron deficiency also appears to protect against certain bacterial infections.⁷⁴ Iron supplementation could therefore increase the severity of bacterial infections in people with AIDS. For that reason, people with HIV infection or AIDS should consult a doctor before supplementing with iron. Learn More

Also indexed as:

ferrous sulfate,
ferrous sulphate,
iron pill,
iron supplements

About this treatment

Side Effects

Caution: Iron (ferrous sulfate) is the leading cause of accidental poisonings in children. The incidence of iron poisonings in young children increased dramatically in 1986. Many of these children obtained the iron from a child-resistant container opened by themselves or another child, or left open or improperly closed by an adult. Deaths in children have occurred from ingesting as little as 200 mg to as much as 5.85 grams of iron. Keep iron-containing supplements out of a child’s reach.

Hemochromatosis, hemosiderosis, polycythemia, and iron-loading anemias (such as thalassemia and sickle cell anemia) are conditions involving excessive storage of iron. Supplementing iron can be quite dangerous for people with these diseases.

Supplemental amounts required to overcome iron deficiency can cause constipation. Sometimes switching the form of iron (see “Which forms of supplemental iron are best?” above), getting more exercise, or treating the constipation with fiber and fluids is helpful, though fiber can reduce iron absorption (see below). Sometimes the amount of iron must be reduced if constipation occurs.

Some researchers have linked excess iron levels to diabetes,cancer, increased risk of infection,systemic lupus erythematosus (SLE), exacerbation of rheumatoid arthritis, and Huntington’s disease. The greatest concern has surrounded the possibility that excess storage of iron in the body increases the risk of heart disease. Two analyses of published studies came to different conclusions about whether iron could increase heart disease risk. One trial has suggested that such a link may exist, but only in some people (possibly smokers or those with elevated cholesterol levels). The link between excess iron and any of the diseases mentioned earlier in this paragraph has not been definitively proven. Nonetheless, too much iron causes free radical damage, which can, in theory, promote or exacerbate most of these diseases. People who are not iron deficient should generally not take iron supplements.

Patients on kidney dialysis who are given injections of iron frequently experience “oxidative stress”. This is because iron is a pro-oxidant, meaning that it interacts with oxygen molecules in ways that can damage tissues. These adverse effects of iron therapy may be counteracted by supplementation with vitamin E.

Supplementation with iron, or iron and zinc, has been found to improve vitamin A status among children at high risk for deficiency of the three nutrients.

People with hepatitis C who have failed to respond to interferon therapy have been found to have higher amounts of iron within the liver. Moreover, reduction of iron levels by drawing blood has been shown to decrease liver injury caused by hepatitis C. Therefore, people with hepatitis C should avoid iron supplements.

In some people, particularly those with diabetes, insulin resistance syndrome, or liver disease, a genetic susceptibility to iron overload has been reported.

References

Last Review: 05-11-2011

Learn more about Aisle7, the company.

The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2011.

© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

Care Circle

It Seems That You Are Not Logged In...

Join Now

Log In
Help

Welcome to Care Circle, an exclusive tool to help you take care of yourself and your loved ones. Here's how it works:

Create profiles for yourself and your loved ones.
Select the topics and conditions that interest each of you.
Get customized news updates, original content, tools, and expert advice for each Care Circle member delivered directly to your personalized homepage.

The information you input is strictly private; you choose who has access to your Care Circle.

Adding Someone
Saving Content
Adding Additional Topics & Conditions
Deleting Topics & Conditions

How do I add myself or someone else to my care circle?

Click on "Add someone." Fill out the short profile. Choose an avatar. Select the topics and conditions that interest this person from the pulldown menu. You can select as many as you want, but you must choose at least one. Click on "Add Someone" again. You should start getting updates immediately.

How do I save content to my Care Circle?

Click on "Manage My Care Circle." Select the tab of the person for whom you're saving content. Put your cursor over the piece of content that you want to save; a disk icon will appear in the righthand corner. Click on the disk and the piece of content will be moved to a save folder.

How do I add additional topics and conditions for someone in my Care Circle?

Click on "Manage My Care Circle." Select the tab for the person whose preferences you'd like to update. Under "Add More to Follow," select additional topics and conditions.

How do I delete topics and conditions for someone in my Care Circle?

Click on "Manage My Care Circle." Select the tab for the person whose preferences you'd like to update. Under "Follows," scroll over the topic or condition you want to delete. An "X" should appear on the righthand side. Click on the "X" and the topic or condition will be deleted from the list.