The Best Time to Take Iron Supplements to Maximize Absorption

Taking your iron supplement at the wrong time of day may affect how it works.

If you’ve been advised to add more iron to your diet, you might be wondering about the best time to take iron supplements. After all, taking an iron supplement may be an effective way to resolve some common symptoms of an iron deficiency—especially if changes to your diet haven’t been enough to improve symptoms like low energy, shortness of breath, pale skin, brittle nails and hair, headaches, and cold hands and feet.

While those signs may lead you to the vitamin aisle at your local grocery store, you shouldn’t load up on supplements without first speaking with your doctor. “Do not take iron just because you are experiencing these symptoms, or you risk iron overload, which can bring different problems to the surface,” says Indhira Ghyssaert, M.D., a family medicine physician and nutritionist.

Dr. Ghyssaert says the best way to determine if you need to add a daily dose of iron to your diet is to talk to your doctor about any symptoms you’re experiencing. They may suggest a blood test to check your levels.

Meet the experts: Indhira Ghyssaert, M.D., a family physician and nutritionist; Gregory Castelli, PharmD., director, pharmacy residency program, UPMC Family Medicine

Once you’ve confirmed with your doctor that an iron supplement is appropriate for you, here’s what to know about iron supplements, including the best time of day to take yours and what medications to avoid while taking iron.

Ideally, you should take your iron supplement first thing in the morning and before foods or other medications to get the best results, says Gregory Castelli, PharmD., director, pharmacy residency program, UPMC Family Medicine.

In addition to the best time of day, Castelli says the frequency at which you take your iron supplements can also play a role in absorption. “Some experts might recommend iron supplementation every other day instead of taking it every day,” he says, which some studies back up. “It may lead to more iron absorption in the long run.” This may be due to how it affects the way your body stores iron, but more research needs to be done on the subject.

According to Castelli, there isn’t much difference between the way your body absorbs iron when taken in a tablet vs. liquid form. That being said, Dr. Ghyssaert says that some people may have a harder time taking the liquid dose because of the taste.

Once you decide which version of the supplement to take, both Dr. Ghyssaert and Castelli agree that it’s important to know what other factors play a role in how well your body handles the supplement.

“Having a stomach pH that is slightly more acidic increases absorption [of iron],” Castelli says. “So foods or products that increase pH will decrease absorption.” Some examples of things that are lower in pH (more acidic) and can help with absorption include citrus-based juices and foods like tomatoes or bell peppers.

While the common advice may be to take iron without other medications, Dr. Ghyssaert says that adding one vitamin, in particular, could actually help you make the most out of your daily dose of iron. “It is highly recommended that you take your iron supplement with your vitamin C supplement,” she says. “This has been proven to help absorption.”

Castelli says that there are also foods that may keep your body from properly absorbing the iron in your supplement, so you should avoid having these shortly before or after taking your supplement. “Calcium-containing products can bind the iron and limit absorption,” he cautions. “Products that contain calcium like dairy, yogurt, cheese, and fortified products decrease iron absorption.”

Additionally, Castelli says that a high intake of eggs, coffee, and tea may also decrease absorption. As such, he says it’s typically best that iron be taken without food if possible.

Pre-existing health conditions may also impact iron absorption. Dr. Ghyssaert says that those with chronic infections, such as hepatitis C, HIV, malaria, ulcerative colitis, or Crohn’s disease, shouldn’t take iron supplements unless directed to do so by their doctor, as it may “increase the risk of infection, and excessive iron can accumulate in the liver and cause damage.”

Over-the-counter medications like antacids (calcium-containing) and acid suppressors like PPIs and histamine blockers can also decrease absorption, according to Castelli. “Patients should separate iron supplementation from the products by a few hours or discontinue these if possible.”

Additionally, Castelli says you’ll need to be mindful of possible interactions if you’re taking the following prescribed medications:

Because of the potential interactions between different foods and medications, Castelli says that taking your iron supplement in the morning is always preferred. But, that’s not the only consideration that makes the start of the day ideal.

“It also can help an individual digest better if they do not lay down immediately after,” explains Dr. Ghyssaert. “So if you do take it at night, stay upright and active for an hour or so before bed. This way you can also keep track of symptoms and any negatives to bring up with your doctor.”

Like with many medications and supplements, there is a chance that you’ll experience side effects. Castelli says the most common side effect people experience is constipation, which he says has a lot to do with the amount of “elemental iron” in the supplement.

“There are many different formulations of iron supplementation including ferrous sulfate, ferrous gluconate, ferrous citrate,” Castelli explains, noting that there is not much difference between these formulations, except for the amount of elemental iron within them. A formulation with less elemental iron may result in lower iron levels and less constipation, he says.

Another potential side effect is stomach upset, which may be exacerbated by taking the supplement on an empty stomach. “If you do have digestive issues, try to find a healthy medium,” Dr. Ghyssaert says. “Take it two hours after your first meal and two hours before your next meal so it can absorb as much as possible.”

Of course, if you’re struggling with the timing of your iron dosage it’s always best to reach out to your doctor or pharmacist and ask them for help determining what time of day is the best time for you to take your iron supplements in order to help with your own specific needs and situation.

Disclaimer: Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing and be sure to consult your doctor before taking new supplements (or providing them to a family member) in any situation, as they can interfere with medication.

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