Blood Disorders Anemia Iron Deficiency Anemia Iron Pills: Side Effects and Benefits of Supplements Iron supplements can treat several conditions but may cause discomfort or toxicity By Tracee Cornforth Updated on September 20, 2023 Medically reviewed by Anisha Shah, MD Print Table of Contents View All Table of Contents Symptoms Risk Factors Benefits Side Effects Management Iron Poisoning Dosage and Preparation Interactions What to Look For Iron supplements, also known as iron pills, are commonly used to treat or prevent iron deficiency anemia. While beneficial in relieving iron deficiency, iron pills can cause side effects like constipation, diarrhea, nausea, vomiting, dark stools, stomach cramps, and a metallic taste. Iron overload (a.k.a. "iron poisoning") is possible if taken in excess. Iron pills are available over the counter and by prescription as capsules, tablets, chewables, gummies, and liquid solutions. Your healthcare provider can help you decide which iron supplement is best for you. This article explains when iron supplements are used and how to use them safely. It also describes iron pill side effects and ways to avoid them. Symptoms of Iron Deficiency Iron is one of the minerals your body needs to function normally. The body uses iron to make hemoglobin, the molecule in red blood cells that "carries" oxygen to cells. When you don't have enough iron, you can develop a type of anemia known as iron deficiency anemia. Symptoms of iron deficiency include: Persistent fatigue Weakness Headaches Dizziness Heart palpitations (skipped beats) Problems concentrating or thinking If allowed to persist, iron deficiency can lead to more concerning symptoms like: Lightheadedness when standing Mouth ulcers Sore tongue Shortness of breath Pallor (pale skin color) Brittle nails Restless leg syndrome (uncontrollable leg movements) A bluish color to the whites of your eye Hair loss Pica (the desire to eat non-food things) Orthostatic hypotension (feeling lightheaded when you stand up) Who Is at Risk for Iron Deficiency? Iron is an important mineral that you can only get from food. Iron deficiency occurs when the iron stores in your body run below what is needed to function normally. The four main reasons for low blood iron include: You lose more blood faster than your body can replace. Your body is unable to properly absorb iron from food (called iron malabsorption). You are not eating enough iron-rich foods. You have a greater-than-normal need for iron (such as being pregnant or breastfeeding). People at Risk of Iron Deficiency There are groups of people who are vulnerable to iron deficiency for different reasons. Iron deficiency due to blood loss can affect people with: Heavy, long, or frequent menstrual periods Peptic ulcer (stomach ulcers) Gastrointestinal bleeding from the overuse of nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, Advil (ibuprofen), or Aleve (naproxen) Cancer of the esophagus (windpipe), stomach, or colon Liver cirrhosis (which can cause esophageal bleeding) Iron deficiency due to iron malabsorption can be caused by: Celiac disease Crohn disease Ulcerative colitis Gastric bypass surgery Excessive antacid use Iron deficiency due to diet can affect those with: A strictly vegan or vegetarian diet Malnutrition Childhood and Pregnancy Children and pregnant people are especially vulnerable to iron deficiency for different reasons: Preterm babies: Infants born prematurely are often deficient because they have lower iron stores than full-term babies. Most iron is transferred from mother to child during the third trimester.Toddlers: Children under 2 years can become iron deficient if they drink too much cow's milk (more than 24 ounces per day) and/or do not eat enough iron-rich foods like leafy vegetables and red meat. Their smaller body size puts them at risk.Pregnancy: During pregnancy, the volume of blood in the body increases, along with the amount of iron needed to function normally. Unless you supplement your normal, iron deficiency can occur.Breastfeeding: During lactation, mothers are susceptible to anemia because of iron depletion and blood loss during childbirth. Benefits of Iron Pills Iron pills are used to treat iron deficiency anemia. They are not typically used to treat other types of anemia (such as vitamin-deficiency anemia, hemolytic anemia, aplastic anemia, or anemia of chronic disease) unless iron deficiency is diagnosed. The amount of iron you need each day depends on your age, sex, and pregnancy status. If you eat a healthy, balanced diet, you probably get enough iron from your food. Supplements can be used if you are not getting enough. The National Institutes of Health (NIH) recommends the following daily intake of iron from all sources for the following groups: Birth to 6 months: 0.27 mgChildren ages 7–12 months: 11 mgChildren ages 1–3 years: 7 mgChildren ages 4–8 years: 10 mgChildren ages 9–13 years: 8 mgMales 14–18 years: 11 mgFemales 14–18 years: 15 mgMales 19–50 years: 8 mgFemales 19–50 years: 18 mgAdults 51 years and older: 8 mgPregnant teens: 27 mgPregnant adults: 27 mgBreastfeeding teens: 10 mgBreastfeeding adults: 9 mg Verywell / JR Bee Iron Pills Side Effects As with any supplement or medication you take, side effects can occur with iron pills. Most tend to be mild but can become severe if you overuse them. Common Side Effects Iron supplements are generally safe and well-tolerated if taken at the recommended dose. The most common side effects include: Upset stomachDark or black stoolsBloatingConstipationDiarrheaGasNauseaStomach crampsVomitingMetallic tasteTeeth staining (when using a liquid iron supplement) Less Common Side Effects Other potential side effects of iron supplements include: BackacheChest pain ChillsDizzinessFaintingFlushing or red skinGroin painHeadacheMuscle sorenessNumbness, pain, or tingling of hands or feetAn overall feeling of weaknessRapid heart rateDouble vision Rare Side Effects In rare cases, a serious allergic reaction known as anaphylaxis can occur when taking iron supplements. Seek immediate emergency care if you experience the following signs and symptoms: Sudden hives or ashRed, swollen, blistered, or peeling skin Swelling of the mouth, face, lips, tongue, or throatTightness in the chest or throatTrouble breathing, swallowing, or talkingWheezingA feeling of impending doom Managing Side Effects Iron supplement side effects can make it difficult for people to take them as prescribed. It often helps to start taking them with a lower dose and gradually increase the dose as tolerated. There are several other tips and tricks that can help: Take iron pills with food to avoid gastrointestinal side effects. Drink plenty of water to prevent constipation. Eat more vegetables and fiber-rich foods to prevent or treat constipation. Eat soluble fiber-rich foods like bananas and sweet potatoes if you have diarrhea. Mix liquid iron with water or juice and drink it through a straw to avoid teeth staining. Brush your teeth and rinse thoroughly after drinking a liquid iron supplement. Sip ginger tea or suck on a ginger candy if you have nausea. Iron Poisoning Taking too much iron can lead to iron overload, also known as iron poisoning. Unlike some minerals, iron is not easily excreted from the body. Once the body's iron stores are full, it can accumulate in the liver, heart, joints, and pancreas and cause organ damage. Heart failure, liver cirrhosis, and hypothyroidism are just some of the possible complications. Excessive doses of iron can lead to iron poisoning. Even a single high dose (60 milligrams per kilogram of body weight or more) can lead to death. Signs of iron poisoning include: Joint pain Abdominal pain Loss of sex drive Erectile dysfunction Pale, clammy skin Unusual tiredness or weakness Depression Late symptoms of iron overdose include: Bluish-colored lips, fingernails, and palms of handsGray or bronze discoloration of the skinWeak, rapid heartbeatsShallow, rapid breathingConvulsions and seizures Contact your healthcare provider immediately if you have iron poisoning symptoms. Risk of Iron Overload From Supplements Overdosing on iron supplements is a less common cause of iron poisoning. Most cases are caused by an inherited disorder called hemochromatosis or when a large transfusion of red blood cells is given. Do I Need My Iron Tested? Dosage and Preparation Iron supplements are taken by mouth and formulated with one of several different types of iron known as: Ferrous sulfate (the most common type)Ferrous gluconateFerrous fumarateFerric citrateFerric sulfate Most iron pills sold in drugstores contain anywhere from 18 to 65 mg of iron. Depending on how much you take, you may meet or exceed the daily value (DV) recommended by the NIH. According to the Office of Dietary Supplements: Multivitamin supplements with iron for women typically provide 18 mg of iron (100% of DV).Multivitamin supplements for men or seniors frequently contain less or no iron.Iron-only supplements usually deliver 65 mg of iron (360% of the DV). While iron is best absorbed on an empty stomach, you should eat a small amount of food to avoid stomach upset. Drink a full 8-ounce glass of water or orange juice with each dose. The vitamin C in orange juice is said to boost absorption. Vegetarians typically need twice as much iron as people who eat meat as the body doesn't absorb iron from plants (non-heme iron) as well as iron from animal-based foods (heme iron). How Long Do Iron Supplements Take to Correct a Deficiency? When used to treat iron deficiency anemia, the duration of iron supplementation may be as long as three to six months. Once started, you would need to continue treatment even if you feel better and no longer have symptoms. Iron Needs for Vegetarians Interactions Calcium and antacids can block the absorption of iron and should not be taken at the same time as an iron supplement. This includes taking an iron supplement with cow's milk. If you use antacids or calcium supplements, avoid taking them two hours before or after an iron supplement dose. Iron supplements may also interact with the following drugs: Antibiotics like tetracycline, penicillin, and ciprofloxacin Levodopa used to treat Parkinson's disease Proton pump inhibitors used to treat acid reflux Synthroid (levothyroxine) used to treat thyroid disease Zinc supplements used to treat zinc deficiency In some cases, separating the doses by two hours may be all that is needed to avoid interactions. In other cases, a dose adjustment may be needed. Speak with your healthcare provider if you intend to take iron supplements with these or any other chronic medication. What to Look For Vitamin and mineral supplements are not subject to rigorous testing in the United States and can vary from one brand to the next. To ensure quality and safety, opt for supplements that have been tested and approved by an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International. Iron supplements can degrade when exposed to excessive temperatures and direct sunlight. To avoid this, keep the supplements in their original light-resistance container and store them in a dry, cool room. Always check the use-by date and discard any expired, discolored, or damaged supplements. Summary Available over the counter and by prescription, iron supplements are mainly used to treat or prevent iron deficiency anemia. Side effects include dark stools, stomach cramps, nausea, diarrhea, constipation, and metallic taste. The dose varies by a person's age, sex, and pregnancy status as well as the cause and severity of the deficiency. Managing Your Anemia With Diet 10 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. MedlinePlus. Iron deficiency anemia. Kumar A, Sharma E, Marley A, Samaan MA. Brookes MJ. Iron deficiency anaemia: pathophysiology, assessment, practical management. BMJ Open Gastroenterol. 2022;9(1):e000759. doi:10.1136/bmjgast-2021-000759 Office of Dietary Supplements/National Institutes of Health. Iron - fact sheet for health professionals. MedlinePlus. Taking iron supplements. Abbaspour N, Hurrell R, Kelishadi R. Review on iron and its importance for human health. J Res Med Sci. 2014;19(2):164-74. Memorial Sloan Kettering Cancer Center. Ferrous Sulfate. Manoguerra AS, Erdman AR, Booze LL, et al. Iron ingestion: an evidence-based consensus guideline for out-of-hospital management. Clin Toxicol (Phila). 2005;43(6):553-70. Centers for Disease Control and Prevention. Hereditary hemochromatosis. Gao C, Li L, Chen B, et al. Clinical outcomes of transfusion-associated iron overload in patients with refractory chronic anemia. Patient Prefer Adherence. 2014;8:513–517. doi:10.2147/PPA.S56238 Li N, Zhao G, Wu W, et al. The efficacy and safety of vitamin C for iron supplementation in adult patients with iron deficiency anemia: randomized clinical trial. JAMA Netw Open. 2020;3(11):e2023644. doi:10.1001/jamanetworkopen.2020.23644 Additional Reading Camaschella, C. Iron deficiency. Blood. 2019;133:30-9. doi:10.1182/blood-2018-05-815944. Office of Dietary Supplements/National Institutes of Health. Iron - Fact Sheet for Health Professionals. Bethesda, Maryland Okan, M.; Koch, T.; Tran, M. et al. Iron Supplementation, Response in Iron-Deficiency Anemia: Analysis of Five Trials. Amer J Med. 2017;130(8):991.e1-991.e8. doi:10.1016/j.amjmed.2017.03.045. By Tracee Cornforth Tracee Cornforth is a freelance writer who covers menstruation, menstrual disorders, and other women's health issues. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit