Endometriosis can cause anemia, and it does so more often than most people realize. A cross-sectional study of endometriosis patients found that over half had iron deficiency, with rates reaching 62% among those with heavy periods. But heavy bleeding isn’t the only reason. Chronic inflammation from endometriosis itself can interfere with how your body absorbs and uses iron, meaning even patients without unusually heavy periods can end up iron-deficient.
How Endometriosis Depletes Iron
There are three distinct pathways connecting endometriosis to iron deficiency, and they can overlap in the same person.
The most straightforward is heavy menstrual bleeding. Up to 68% of endometriosis patients experience abnormally heavy periods, often because of an overlap with adenomyosis (a related condition where endometrial tissue grows into the muscular wall of the uterus). Every heavy cycle drains iron stores faster than diet alone can replenish them. Over months and years, this creates a deepening deficit.
The second pathway is inflammation. Endometriosis is a chronic inflammatory condition, and the inflammatory molecules it produces can disrupt the system your gut uses to absorb iron. Specifically, these molecules interfere with a hormone called hepcidin that regulates how much iron passes from your intestines into your bloodstream. When hepcidin signaling goes haywire, your body absorbs less iron from food even when you’re eating enough of it. A population-based cohort study confirmed that the link between endometriosis and iron deficiency persists even after accounting for heavy bleeding, though heavy periods explained roughly 8% of the association.
The third pathway involves overlapping autoimmune conditions. Endometriosis frequently co-occurs with inflammatory bowel disease and other autoimmune disorders that impair the gut’s ability to absorb nutrients, including iron. Many of these conditions go undiagnosed for years, silently compounding the problem.
Why Iron Deficiency Gets Missed
One of the biggest challenges is that iron deficiency and endometriosis produce nearly identical symptoms: fatigue, weakness, dizziness, irritability, poor concentration, sleep disturbances, and depression. When a patient with known endometriosis reports crushing fatigue, it’s easy to attribute everything to the disease itself and never check iron levels. This symptom overlap means many cases of iron deficiency go undiagnosed and untreated, leaving patients feeling far worse than they need to.
Testing adds another layer of complexity. The standard screening test for iron deficiency is serum ferritin, a protein that reflects your body’s iron stores. The WHO threshold for deficiency in non-pregnant women is below 15 μg/L, though newer research suggests that hemoglobin levels actually start declining at ferritin levels below about 25 μg/L, meaning many women are functionally deficient well before they hit the official cutoff. For endometriosis patients specifically, there’s an additional wrinkle: ferritin is what’s known as an acute-phase reactant, meaning inflammation can push ferritin levels up even when iron stores are genuinely low. A person with endometriosis could have a “normal” ferritin reading and still be iron-deficient. Researchers have recommended that clinicians use a second marker called transferrin saturation alongside ferritin to get an accurate picture in patients with inflammatory conditions.
If you have endometriosis and experience persistent fatigue, shortness of breath during mild activity, headaches, or brain fog, it’s worth asking for a full iron panel rather than relying on a ferritin test alone.
Treating Iron Deficiency With Endometriosis
Managing anemia in endometriosis involves two goals: replenishing iron stores and reducing ongoing iron loss.
For replenishing iron, oral supplements are the first-line approach. Therapeutic doses typically range from 80 to 100 mg per day, taken for four to eight weeks. Even doses as low as 20 mg daily have been shown to meaningfully improve iron deficiency symptoms. The tradeoff is that higher doses cause more gastrointestinal side effects (nausea, constipation, stomach pain), particularly above 100 mg per day, which makes it harder to stick with treatment. Taking supplements every other day instead of daily can reduce side effects while still being effective.
If oral supplements don’t work, or if you can’t tolerate them, intravenous iron is a safe alternative. A single infusion can deliver up to 1,000 mg of iron in one session, which is far more than weeks of oral supplements would provide. This option is particularly useful for people whose gut inflammation limits iron absorption.
For reducing ongoing iron loss, hormonal treatments that lighten or suppress periods are often part of the strategy. Options include hormonal IUDs, certain birth control pills, or other hormonal therapies that are already commonly used to manage endometriosis symptoms. Lighter periods mean less iron lost each month, giving your body a chance to rebuild its reserves.
How Long Recovery Takes
Restoring iron stores is not a quick fix. In clinical trials, people who started with low ferritin levels and took iron supplements saw their levels return to baseline in a median of about 21 days. But reaching robust, healthy iron stores (ferritin of 26 μg/L or higher) took a median of 120 days, with some people needing more than five months. For those who started with moderate iron levels, full recovery took a median of 107 days.
This means you should expect to take supplements for at least three to four months before your stores are reliably rebuilt, and you may start feeling better well before your labs fully normalize. The fatigue, brain fog, and dizziness that iron deficiency causes often begin improving within a few weeks of starting treatment.
Iron-Rich Foods and Dietary Considerations
Diet alone rarely corrects established iron deficiency, but it plays a supporting role in maintaining levels after treatment. The relationship between iron-rich foods and endometriosis requires some nuance, though. Red meat is one of the most bioavailable sources of iron, but its high iron content can also amplify oxidative stress and inflammation, which is counterproductive for an inflammatory condition like endometriosis.
A more balanced approach focuses on lean proteins like poultry and fish, paired with plant-based iron sources such as lentils, spinach, and fortified grains. Vitamin C from fruits and vegetables significantly increases iron absorption from plant foods, so combining them at the same meal helps. Current evidence suggests that people with endometriosis benefit from diets rich in antioxidants and anti-inflammatory nutrients: fruits, vegetables, whole grains, and healthy fats like those found in olive oil and fatty fish. This approach supports both iron status and overall endometriosis management without fueling inflammation.