Can Iron Deficiency Cause Hair Loss?

"I felt tired and occasionally dizzy, so I thought it was anemia, but I'm also losing a lot of hair."

When treating female hair loss patients, I find that many also suffer from chronic fatigue, dizziness, lethargy, and headaches. These are classic signals that the body is deficient in 'Iron,' and they are very deeply connected to hair loss. While many people think of anemia and hair loss as separate issues, scientific research clearly shows they are closely linked.

1. Scientific Evidence: Correlation Between Iron Deficiency and Hair Loss

Iron is a core component of hemoglobin in red blood cells, which transport oxygen to every cell in our body. If iron is deficient, the 'hair follicles'—the factories that produce hair—cannot receive adequate oxygen and nutrients, leading to hair loss. Multiple studies have confirmed that patients with female pattern hair loss and telogen effluvium have significantly lower iron storage (ferritin levels) than healthy individuals. In particular, it has been revealed that 'iron deficiency without anemia'—a state where general anemia tests (hemoglobin) are normal but ferritin levels are low—is also a major risk factor for hair loss.

2. What is Ferritin and Why is it Important?

Regarding hair loss, we must focus not only on general anemia levels (hemoglobin) but also on 'Ferritin' levels. Ferritin represents the 'iron stored in the warehouse' of our body. If hemoglobin in the blood is like 'cash in your wallet' for immediate use, ferritin is like 'savings in a bank account' to be withdrawn during emergencies. When the body lacks iron, it first takes the ferritin stored in hair follicles—a part considered less essential for survival. As a result, the follicles fall into a state of iron depletion and transition into the resting (telogen) phase before completing their full growth cycle.

3. The Trap of 'Normal Levels': Low Normal is Not Normal

Many patients feel relieved after a blood test when told their "ferritin levels are within the normal range." However, the normal range for ferritin in blood tests is very broad, typically between 10 and 150 ng/mL. From the perspective of hair health, a ferritin level of 15 or 20 is 'low normal,' which is grossly insufficient for hair to grow healthily. Clinically, I believe a ferritin level of at least 50 ng/mL must be maintained for healthy hair growth.

4. How Should You Supplement Iron and Ferritin?

If your levels are already low, it is best to replenish them quickly through supplements or injections. To raise ferritin levels, iron supplements must be taken. Since the required dose varies depending on the individual's degree of deficiency, you must consult a doctor or pharmacist; therapeutic doses are often prescribed between 100mg and 200mg of elemental iron per day. Iron supplements must be taken consistently for at least 3 to 6 months to not only normalize blood levels but also sufficiently fill the ferritin 'warehouse.'

5. Will Hair Regrow Just by Taking Iron Supplements?

If iron deficiency were the 'sole' cause of your hair loss, you would see great effects just by taking supplements. However, most female hair loss patients have complex, overlapping causes such as stress, hormonal changes, and scalp inflammation in addition to iron deficiency. Therefore, while low iron or ferritin levels identified in blood tests must be corrected, you must also engage in proactive hair loss treatment to recover weakened follicle function and resolve other root causes to regain hair volume and make thinning hair thick and healthy again.