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Iron (for Deficiency-Related Fatigue)

Reviewed by the Nimbera editorial team · Last updated May 2026

Barton et al. 2018 review (Cochrane Syst Rev, PMID 29626044) - oral iron supplementation significantly improves fatigue, physical performance, and cognitive function in women with iron deficiency (with or without anaemia). Effect size is large; results emerge within 4-8 weeks of treatment.$10-$30/month depending on form.

How to use

Take iron supplements only if blood tests confirm iron deficiency or iron-deficiency anaemia (ferritin < 30 ng/mL or as directed by your doctor). Typical dose: 100-200 mg ferrous sulfate, or 15-25 mg iron bisglycinate daily (better tolerated). Take on an empty stomach with vitamin C to enhance absorption. Avoid taking with coffee, tea, calcium, or antacids.

How it works

Iron is the core of haemoglobin (oxygen transport in red blood cells) and myoglobin (oxygen storage in muscle), as well as enzymes in the mitochondrial electron transport chain. Iron deficiency impairs oxygen delivery to tissues and mitochondrial energy production - correcting deficiency directly restores energy capacity.

Where to buy

Floradix Iron + Herbs liquid ($20-$30/250 ml, gentle form), Thorne Iron Bisglycinate ($15-$20/60 capsules), NOW Foods Iron ($8-$12/120 tablets - ferrous bisglycinate) - available at pharmacies and health food stores.

Typical cost: $10-$30/month depending on form.

Safety notes

DO NOT supplement iron without a blood test confirming deficiency. Iron toxicity is a medical emergency; excess iron causes oxidative damage to organs. Common side effects at higher doses: constipation, dark stools, nausea - bisglycinate form reduces GI effects. Hereditary haemochromatosis (iron overload gene): iron supplementation is contraindicated. Interactions: reduces absorption of levothyroxine, fluoroquinolone antibiotics, bisphosphonates - space by at least 2 hours.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Barton et al. 2018 - Cochrane Syst Rev (PMID 29626044)

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.