A Quick & Easy Guide to Choosing the Right Iron Supplement

So, you’re in need of an oral iron supplement and head to the pharmacy where you’re greeted by an overwhelming selection. How do you pick the right one without resorting to an impromptu game of eeny, meeny, miny, moe? Keeping in mind that every body is different (and a one-size-fits-all iron supplement does not exist), I recommend that the “right” iron supplement is one that patients can tolerate with the least amount of side effects.

Here I’ve put together a quick and easy guide to help you choose the right iron supplement for you, and as always, your doctor or pharmacist are great resources to help you understand the available options.


When choosing an iron supplement, consider the following:

1.      Elemental Iron

When choosing your iron supplement, instead of looking at the overall strength (or weight), look at the amount of elemental iron. Elemental iron is the amount of iron available for absorption. For example, an iron supplement may read “300 mg” on the front of the bottle, but only contain 60 mg of elemental iron.

Speaking of absorption, you’ll want to ensure that your body absorbs as much iron from your supplement as possible and you can do this by taking it on an empty stomach (if tolerated) or with foods that are high in vitamin C, which has been found to enhance iron absorption (this is not necessary, however, when taking an iron supplement formulated with polysaccharide-iron complex or heme iron polypeptide).

Learn more about the elemental iron content in some available Canadian brands here →


2.      Side Effects

Oral iron supplements can cause some unpleasant gastrointestinal (GI) side effects, like nausea, vomiting, diarrhea or constipation, and dyspepsia (indigestion). These are usually a result of dosing and typically subside with continued therapy. As noted in the Anemia Guidelines for Family Medicine (2014), you can enhance tolerance by starting with a small daily dose (eg. 1 tablet daily) and gradually increasing it. Taking it with or after a meal can also make it easier on your belly, but this decreases the amount of iron you will absorb, so just keep that in mind.

Learn more about the side effect profiles of some available Canadian brands here →


3.      Convenient Dosing

Let’s face it; the easier a supplement is to take, the more likely you are to take it as required, right? For this reason it’s a good idea to read the recommended dosing or check with your pharmacist. Compliance is a crucial part of iron supplementation and treating iron deficiency, so look for a supplement with a dosing schedule that fits your lifestyle.

Learn more about the recommended dosing of some available Canadian brands here →


Choosing the best iron supplement is about making it as easy on you as possible. You want a supplement that gives you the most bang – or elemental iron in this case – for your buck, that also happens to be easy to take as far as convenience and side effects go. Speak to your doctor or pharmacist about your needs and which supplement is right for you.

For more information on treatment options and different types (or classes) of iron supplements, check out my work with Dr. Marla Shapiro in a segment called Understanding and Treating Iron Deficiency and Iron Deficiency Anemia.

Content and advice provided on The Iron Maiden is for information purposes only and should not serve as a substitute for a licensed health care provider, who is knowledgeable about an individual’s unique health care needs

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8 thoughts on “A Quick & Easy Guide to Choosing the Right Iron Supplement

  1. Kim Dupuie says:

    Had rny in July what is the right iron pill for me I do eat red meat and I am in the US. I bought 65mg/325 MG ferrous Sulfate is this the right thing thanks

    • Leona, RN & Blood Specialist says:

      Hi Kim, I typically do not recommended iron salts for gastric bypass patients as the section of small intestine, where the iron is absorbed, is the section that has been bypassed. For these patients I would recommend either a heme iron or a polysaccharide iron. Unfortunately I am not well versed on what is available in the United States. Please ask your pharmacist for more information on heme iron or polysaccharide iron and they can steer you in the right direction.


  2. Corri says:

    Reading this and other questions you’ve answered has really helped me to better understand iron supplements and what’s best for me. Thanks! It’s Feramax for me all the way 🙂


      Amazing! Glad to know that this blog has helped you in your journey to improving your health and quality of life! Please help me in educating your friends and family as well!


    • The Iron Maiden says:

      Hi Sakshi

      In a normal unaltered gut there really isn’t one iron better than another. Assuming that this is your case we must look at things that might help you decide what is the best option. Many first look at the price. While the per dose cost of ferrous fumerate (3/day) is less expensive than a polymaltose complex (1/day) dose the actual cost of daily therapy is the same. A second consideration is the amount of elemental iron that is available for absorption. Ferrous Fumerate has 300 mg however, when taken in optimal conditions (on an empty stomach, the absence of coffee, tea, cola, chocolate, dairy, dairy substitute, calcium, or stomach acid reducing medications and with Vitamin C) only 8% (23mg) of that iron is available for absorption. The remainder of the iron passes through your gut undigested resulting in that black tarry constipated stool we all associate with iron supplementation. The Polymaltose Complex Iron has 150mg of elemental iron, it’s digestion for absorption is not effected by the iron inhibitors listed above, nor is it necessary to take on an empty stomach or with Vitamin C. The portion of the polymaltose complex supplement that is not absorbed sucks water with it into the colon making it easier to eliminate.

      So a quick review of the considerations are: similar daily therapy costs, fewer gastro intestinal side effects with Polymaltose Complex Supplements (looser than normal stool vs. constipation), fewer rules to optimizing absorption with Polymaltose Complex Supplements. Better compliance with Polymaltose Complex Supplements because of the decrease in side effects and requirements for maximizing absorption.

  3. Frustrated in Canada says:

    I’m taking 2 feramax a day and I eat red meat within reason, but my ferritin levels are always either just skimming the bottom of the range, or below it. I used to take 3 or 4 ferrous fumarate a day, but that was not getting the ferratin levels even into the bottom of the normal range. I’ve asked the GPs I’ve had if there’s any iron formulation that might be more effective but they just say keep doing what you’re doing. But what I’m doing isn’t working, so I don’t know what to do.

    I have PCOS and IBS and am a female over 40 who has never been pregnant. Do you have any advice?

    • The Iron Maiden says:

      HI Frustrated in Canada,

      Boy do I feel your pain! With PCOS and IBS I venture to guess that you have dealt with iron deficiency most of your adult life.

      Approximately 20% of Canadian women suffer from iron deficiency. It is one of the most under-treated health issues. You need to pressure your physician to do a proper assessment of your iron stores. An iron panel (serum iron, TIBC, and %Transferrin Saturation) and a Ferritin Level to determine if oral iron will deplete your iron stores. If your iron panel indicates iron deficiency and your ferritin is normal it is safe to assume your ferritin level is falsely elevated. A referral to a benign clinical Haematologist may be necessary to get definitive treatment (IV iron or intramuscular iron) once your iron stores are repleted you need to keep those stores up by taking an appropriate iron supplement in a specific quantity unique to you.

      Keep us posted on your progress.


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