Have you ever dragged yourself through the day, battling persistent brain fog, cold hands, and an unexplainable bone-deep fatigue, only to brush it off as a busy lifestyle? For millions of women, the culprit isn’t just lack of sleep; it is iron deficiency driven silently by monthly menstrual cycles
Iron is the essential spark engine of human metabolism, vital for carrying oxygen to your brain and muscles. Yet, every month, regular menstrual bleeding drains 10 to 20 mg of iron from bodily stores. When bleeding is heavy, the body can lose more iron than it replaces. Over time, this can use up its stored iron, even while red blood cells are still being produced normally.
You Don’t Have to Be Anemic to Be Low in Iron
Here’s the part that often gets overlooked: iron deficiency can happen before anemia.
Your body stores iron in a protein called ferritin. When you’re losing more iron than you’re replacing, your body starts drawing from these reserves. This is called nonanemic iron deficiency (NAID): your iron stores are depleted, but your standard blood counts can still look normal.
If the deficiency continues, it can eventually progress to iron-deficiency anemia (IDA), when there isn’t enough iron to support normal red blood cell production.
That means you can experience the effects of low iron before a routine blood count shows anemia.
What Does Low Iron Actually Feel Like?
Iron does much more than help your blood carry oxygen. Your body also needs it for cellular energy production, brain neurotransmitter synthesis, and muscle function. When stores run low, you might notice:
- Persistent fatigue or exhaustion
- Brain fog and difficulty concentrating
- Lower exercise tolerance
- Cold hands and feet
- Restless legs
- Hair thinning, dry skin, or brittle nails
These symptoms aren’t proof of iron deficiency on their own, but when they appear alongside heavy periods, they’re worth paying attention to.
Could Your Period Be the Reason?
For the 18% to 50% of menstruating individuals who experience heavy menstrual bleeding, monthly iron loss can be significantly higher than normal. Losing more than 80 mL of blood per cycle is considered heavy menstrual bleeding.
You don’t have to measure your blood loss to recognize that something might be off. Signs can include:
- Soaking through a pad or tampon every hour
- Bleeding for more than seven days
- Passing large blood clots
Despite how common iron depletion is, conversations about menstrual bleeding don’t always happen in medical appointments. Research has found that providers documented discussions about menstruation in only about half of patients later diagnosed with iron deficiency.
So, What Can You Do?
Eating iron-rich foods can help support your iron levels, but diet alone usually isn’t enough to treat an existing deficiency. This is especially true when your body is continuing to lose iron through menstruation.
First, get your iron levels checked. A standard complete blood count (CBC) can identify anemia, but it may not catch depleted iron stores. A serum ferritin test measures stored iron and can provide a clearer picture of your iron reserves.
And despite a common myth, iron supplements don’t appear to make periods heavier. One randomized trial found that taking 50 mg of elemental iron during the first four days of menstruation did not increase blood loss.
Treatment can include oral iron, sometimes using alternate-day dosing to reduce digestive side effects and improve absorption. For people who can’t tolerate oral iron or have more severe deficiency, IV iron may be an option.
Your period might be normal for you, but feeling completely drained every month doesn’t have to be. If your body keeps losing more iron than it can replace, that exhaustion may be a sign that your iron stores need some attention.
Sources
MokhtarKalimi, E., Loripoor, M., Rezaeian, M., & Gholamrezapour, M. (2024). The effect of iron supplementation on menstrual bleeding volume and hemoglobin level during menstrual bleeding: A randomized clinical trial. Journal of Education and Health Promotion, 13, 19.
https://doi.org/10.4103/jehp.jehp_1871_22
Munro, M. G., Mast, A. E., Powers, J. M., Kouides, P. A., O’Brien, S. H., Richards, T., Lavin, M., & Levy, B. S. (2023). The relationship between heavy menstrual bleeding, iron deficiency, and iron deficiency anemia. American Journal of Obstetrics & Gynecology.
https://doi.org/10.1016/j.ajog.2023.01.017
Patel, N. N., & Samuelson Bannow, B. (2026). Disparities in discussion of heavy menstrual bleeding in patients with iron deficiency. Journal of Primary Care & Community Health, 17, 21501319261431599.
https://doi.org/10.1177/21501319261431599
Sholzberg, M., Hillis, C., Crowther, M., & Selby, R. (2025). Diagnosis and management of iron deficiency in females. CMAJ, 197(24), E680–E687.
https://doi.org/10.1503/cmaj.240570
