Counsel Patients About OTC Iron Supplements for the Management, Prevention of Iron Deficiency

Pharmacy TimesMay 2024
Volume 90
Issue 5

Early signs and symptoms can be vague and are often overlooked

Iron deficiency is recognized as the most common form of nutritional deficiency and, if left untreated, can progress to iron-deficiency anemia, the most common type of anemia around the world.1 Iron deficiency typically progresses in stages. According to the National Institutes of Health’s Office of Dietary Supplements, these stages start with the depletion of iron stores (classified as mild iron deficiency), then iron-deficiency erythropoiesis, and, lastly, various degrees of iron-deficiency anemia.2

iron supplement pills .Iron is used to treat anemia due to iron deficiency anemia, IDA, which is caused by chronic blood loss -  Image credit: BooDogz |

Image credit: BooDogz |

Pharmacists are well poised to educate and guide patients in properly selecting and using nonprescription iron supplements. To ensure the appropriateness of OTC supplements and to ascertain the best course of treatment, pharmacists can also encourage patients to seek further medical advice from their primary health care provider before using iron supplements and to obtain a medical evaluation to establish the contributing cause and degree of the iron deficiency.

Causes of Iron Deficiency

Although iron is naturally contained in numerous foods, many individuals still do not meet their recommended daily intake for their age group via diet alone, which may augment the risk of developing iron deficiency and iron-deficiency anemia. Research has established that well-documented causes of iron deficiency and iron-deficiency anemia can include decreased iron intake, increased demand for iron, reduced iron absorption, and decreased iron due to blood loss. Examples of causes are documented in Table 1.3-6

Clinical Presentation

The early signs and symptoms associated with iron deficiency are often vague and may initially go unnoticed. However, as the body becomes more deficient in iron stores, patients may present with varying degrees of symptoms depending upon the severity of the anemia, the patient’s overall health, and the presence of chronic medical conditions. Signs and symptoms often associated with iron-deficiency anemia may include, but are not limited to, unexplained fatigue, weakness, pale skin, tachycardia, dizziness, brittle nails or hair loss, and compulsive craving for ice (pagophagia).3-7

About the Author

Yvette C. Terrie, BSPharm, RPh, is a consulting pharmacist and medical writer in Haymarket, Virginia.

News and Clinical Data

Although the exact incidence is unknown, a recent publication in JAMA indicated that between 2003 and 2020, among female patients aged 12 to 21 years, iron deficiency affected an estimated 40% of this population, and iron-deficiency anemia affected 6%. The authors also noted that menstruation was a risk factor for both iron deficiency and iron-deficiency anemia, but more than 25% of premenarchal individuals also had iron deficiency.8 Based on these findings, the authors wrote, “Given the high prevalence of iron deficiency found with the majority not associated with iron-deficiency anemia, current screening guidance may miss many individuals with iron deficiency.”8

OTC Iron Supplements

Currently, OTC iron supplements on the market include ferrous fumarate, ferrous sulfate, and ferrous gluconate, which are indicated for the treatment and prevention of iron deficiency and iron-deficiency anemia under the routine supervision of a health care provider.9 Supplements are available in immediate and controlled release formulations in various dosage forms, including tablets, caplets, in an enteric form to decrease gastric irritation, gummies, chewables, and liquids. Available formulations include single entity iron-containing products or iron in multivitamin supplements.

Ferrous salt formulations are often recommended to be administered with ascorbic acid (vitamin C) to improve absorption.9 Some clinicians may advise patients to take iron supplements with fruit juices high in ascorbic acid, such as orange juice, when appropriate.9 There are some combination products containing both iron and ascorbic acid, formulated to help the body absorb iron more effectively and to cause less constipation.9

For the best absorption, iron supplements should be taken on an empty stomach. To avoid stomach irritation, however, many manufacturers recommend that these supplements be taken with meals, although some foods and beverages, such as cereals, milk, tea, and coffee, may decrease iron absorption.9 In addition, iron may interfere with the absorption of numerous medications, such as antibiotics (i.e., tetracyclines, fluoroquinolones), antacids, proton pump inhibitors, and histamine receptor blockers, as well as calcium supplements.9-11 Therefore, dosing should be spaced at least 2 hours apart.9-11

The most common adverse effect associated with the use of iron supplements is constipation, and when appropriate, patients may be advised to consider the use of an OTC stool softener. Some iron supplements are formulated with a stool softener to avoid this adverse effect.9


Pharmacists can be instrumental in identifying patients at risk for iron deficiency or those who are exhibiting symptoms. These patients should be encouraged to pursue further medical evaluation to ascertain the appropriateness of therapy. Due to their drug expertise, pharmacists can screen for potential interactions and contraindications and make patient-centered clinical recommendations.

During counseling, pharmacists should inform patients that in addition to constipation, iron supplements may cause gastrointestinal irritation, nausea, dark stools, and abdominal pain.9 Patients using iron supplements should be reminded not to use any other multivitamin supplements containing iron while using iron supplements to prevent iron toxicity and should only take these supplements as directed under the supervision of their primary health care provider.

Patients should be encouraged to contact their primary health care provider if they experience adverse effects or if symptoms worsen. They should also be advised to continue routine checkups with their primary health care provider to monitor laboratory results and their responses to iron therapy, establish the duration of treatment, and determine whether therapy changes are warranted.

  1. Micronutrients. Centers for Disease Control and Prevention. January 16, 2024. Accessed April 2, 2024.
  2. Iron: fact sheet for health professionals. National Institutes of Health Office of Dietary Supplements. Updated June 15, 2023. Accessed April 2, 2024.
  3. Iron-deficiency anemia. National Heart, Lung, and Blood Institute. Updated March 24, 2022. Accessed April 2, 2024.
  4. Gerber GF. Iron deficiency anemia. Merck Manual for Healthcare Professionals. June 2023. Accessed April 2, 2024.
  5. Auerbach M, DeLoughery TG. Causes and diagnosis of iron deficiency and iron deficiency anemia in adults. March 2024. Accessed April 2, 2024.
  6. Iron-deficiency anemia. John Hopkins Medicine. Accessed April 2, 2024.
  7. Iron-deficiency anemia. American Society of Hematology. Accessed April 2, 2024.
  8. Weyand AC, Chaitoff A, Freed GL, Sholzberg M, Choi SW, McGann PT. Prevalence of iron deficiency and iron-deficiency anemia in US females aged 12-21 years, 2003-2020. JAMA. 2023;329(24):2191-2193. doi:10.1001/jama.2023.8020
  9. Krinsky DL, Ferreri SP, Hemstreet BA, Hume AL, Rollins CJ, Tietze KJ, eds. Handbook of Nonprescription Drugs: An Interactive Approach to Self-Care. 20th Eedition. American Pharmacists Association; 2020.
  10. Vergnaud S. Iron: overview, supplement side effects, and more. GoodRx. March 23, 2022. Accessed April 2, 2024.
  11. Taking iron supplements. Medline Plus. July 8, 2023. Accessed April 2, 2024.
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