Discussions of steroids and iron levels often reach the wrong conclusion. Because anabolic-androgenic steroids (AAS) increase red blood cell production, it is sometimes assumed that users need more iron to keep up with the demand.
The physiology points the other way. Testosterone increases the body’s access to iron rather than depleting it, and the usual problem for AAS users is too many red blood cells, not too few. Adding iron supplements without a diagnosed deficiency is unnecessary for most men and can be counterproductive.
This article explains how AAS affect red blood cells and iron, when iron deficiency is actually a concern, and what is worth monitoring.
How do anabolic steroids affect red blood cells?
Testosterone and related compounds stimulate the production of red blood cells through several routes. They increase erythropoietin, the hormone that signals the bone marrow to make red blood cells, act on red blood cell precursors in the marrow, and suppress hepcidin, a hormone that controls how much iron the body absorbs and releases from storage.
The result is a rise in hemoglobin and hematocrit, the proportion of blood made up of red blood cells. This is one of the most consistent effects of AAS use. In the HAARLEM study, which followed 100 men through a cycle, increases in hematocrit were among the most reliably observed changes (Smit et al., 2022).
Erythrocytosis, an abnormally high red blood cell count, is also the most common adverse effect of medically supervised testosterone therapy (Bhasin et al., 2018).
Does this mean steroid users need more iron?
Usually not, and this is where the common advice goes wrong.
Suppressing hepcidin increases iron absorption from the diet and releases iron from the body’s stores. In other words, testosterone makes iron more available, not less. That extra iron is directed into making red blood cells.
Blood tests can reflect this. Ferritin, a marker of stored iron, may fall during testosterone use because stored iron is being used. On its own, that is a sign of iron being put to work, not of a deficiency requiring supplements. Interpreting it correctly requires a doctor looking at the full picture, including hemoglobin and hematocrit.
Taking iron on the assumption that it must be low risks making the real problem worse, since the underlying issue is usually a red blood cell count that is too high.
Why a high red blood cell count matters
More red blood cells make the blood thicker, which can increase the risk of clots. Our article on whether steroids cause blood clots explains the evidence on clotting risk.
Clinical guidance for testosterone therapy treats a hematocrit above roughly 54% as a threshold for action, which may involve reducing or stopping treatment, or in some cases removing blood (Bhasin et al., 2018). These are medical decisions requiring a doctor, not something to manage independently.
AAS use is also associated with raised blood pressure and changes in heart structure, so a high hematocrit adds to a cardiovascular picture that is already affected.
When is iron deficiency a genuine concern?
Iron deficiency does occur in athletes, but the groups most affected are not usually men using AAS:
Women who menstruate, whose iron requirements are considerably higher.
Endurance athletes, particularly runners, due to losses through sweat, the gut, and foot-strike damage to red blood cells.
People eating vegetarian or vegan diets, since plant-based iron is less readily absorbed.
Anyone with a condition causing blood loss, including gastrointestinal bleeding.
Symptoms of iron deficiency include persistent fatigue, breathlessness on exertion, pale skin, dizziness, and brittle nails. These overlap with many other conditions, including some caused by AAS use, which is why they cannot be used to diagnose a deficiency.
Iron deficiency is diagnosed with blood tests, usually including ferritin and a full blood count, not by matching symptoms to a list.
What are the risks of taking iron unnecessarily?
Iron supplements are not harmless.
Gastrointestinal effects are common, including constipation, nausea, and stomach pain.
Iron overload can occur with long-term unnecessary supplementation. Excess iron accumulates in the liver, heart, and other organs. The tolerable upper intake level for adults is 45 mg per day from all sources.
Hereditary hemochromatosis, a genetic condition causing excessive iron absorption, is relatively common in people of northern European ancestry. Someone with it who takes iron supplements can accelerate organ damage, and many people are unaware they have it.
Interference with other minerals, since high iron intakes can affect zinc absorption.
Our article on vitamins and minerals for steroid users covers safe upper limits for other supplements.
How much iron do most people need?
The recommended intake for adult men is 8 mg per day, and for women who menstruate, 18 mg per day. A varied diet usually meets this.
Heme iron, from meat, poultry, and fish, is absorbed more readily.
Non-heme iron, from beans, lentils, tofu, nuts, seeds, and leafy greens, is absorbed less efficiently, though vitamin C eaten in the same meal improves absorption.
For men eating a mixed diet, including those who train hard, meeting the requirement is rarely difficult.
What is worth monitoring?
Anyone using or recovering from AAS benefits from periodic blood tests ordered and interpreted by a doctor, which typically include a full blood count showing hemoglobin and hematocrit. Being open about AAS use matters, because a raised hematocrit has a clear explanation that a doctor needs to know.
Seek medical advice for persistent fatigue or breathlessness rather than assuming it is low iron, and seek urgent care for chest pain, severe shortness of breath, or swelling and pain in one leg.
Our guide to the key facts about steroids covers the broader effects of AAS on the body.
The bottom line
The relationship between steroids and iron levels is the opposite of what is often claimed. AAS increase red blood cell production and make iron more available by suppressing hepcidin, so the typical issue is an elevated red blood cell count rather than a shortage of iron.
Iron supplements are not a performance aid and carry real risks, including iron overload and accelerated organ damage in people with undiagnosed hemochromatosis. Iron deficiency should be diagnosed with blood tests and treated under medical supervision, not assumed from symptoms or from the fact that steroids raise red blood cell production.
References
Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2018;103(5):1715–1744.
Office of Dietary Supplements, National Institutes of Health. Iron: fact sheet for health professionals.
Smit DL, et al. Prospective study on blood pressure, lipid metabolism and erythrocytosis during and after androgen abuse. Andrologia. 2022;54(4):e14372.
