Best Iron Supplements for Perimenopause and Heavy Periods

Why Iron Deficiency Is Common During Perimenopause

Heavy and irregular periods are among the most common experiences of perimenopause. When estrogen is not being properly balanced by progesterone, the uterine lining can build up more than usual and shed heavily. This kind of flooding or prolonged bleeding can cause significant iron loss. Iron deficiency and iron-deficiency anemia are a direct consequence for many women. The symptoms, fatigue, brain fog, shortness of breath, poor sleep, cold hands and feet, and low mood, overlap so completely with other perimenopause symptoms that iron deficiency often goes undetected for months or even years. If you are dealing with heavy periods and persistent fatigue during perimenopause, getting a ferritin test is one of the most practical first steps you can take.

Understanding Iron Forms: Why Not All Supplements Are Equal

Iron supplements come in several forms, and the form matters for both absorption and tolerability. Ferrous sulfate is the most widely available and least expensive form. It absorbs reasonably well but is associated with the highest rates of constipation, nausea, and stomach upset. Ferrous bisglycinate, also called iron bisglycinate or iron glycinate, is a chelated form that absorbs well and is significantly gentler on the digestive system. It is the most commonly recommended form for women with GI sensitivity. Ferric iron forms, the older standard before chelated forms became available, have lower absorption rates and are generally less preferred today. Heme iron supplements derived from animal sources are highly bioavailable and easy to tolerate, though they are not suitable for vegetarians or vegans. Liposomal iron is a newer format with good absorption and minimal GI side effects, though it is more expensive.

Dosage and What to Expect From Testing

The appropriate dose of iron depends on how depleted your stores are, which is why getting a ferritin test before starting supplementation is worth doing. Ferritin is the storage form of iron, and low ferritin can cause symptoms even when hemoglobin levels appear normal on a standard blood count. Most doctors recommend a treatment dose of 100 to 200mg of elemental iron per day for deficiency, but lower daily doses spread across the week may actually absorb better. Recent research suggests that taking iron every other day rather than daily can increase absorption by reducing hepcidin, the hormone that regulates iron absorption and rises in response to daily dosing. This every-other-day approach also tends to reduce side effects significantly.

Improving Absorption and Avoiding Common Mistakes

Vitamin C taken alongside iron significantly enhances absorption. Pairing your iron supplement with a glass of orange juice or a vitamin C supplement is a simple habit worth building. Calcium, on the other hand, competes with iron for absorption and should be taken at least two hours apart from iron. This is an important consideration for women who also take calcium supplements or eat calcium-rich foods. Coffee and tea contain tannins and polyphenols that inhibit iron absorption and should be avoided for at least an hour before and after taking an iron supplement. Taking iron on an empty stomach maximizes absorption but tends to worsen GI side effects for women with sensitive stomachs. Taking it with a small amount of food is a reasonable compromise.

Signs That Your Iron Levels Are Improving

Fatigue and brain fog tend to be among the first symptoms to improve as iron stores rebuild. Energy typically improves within two to four weeks of consistent supplementation, though full restoration of ferritin levels can take three to six months of sustained supplementation even with good adherence and absorption. Hair shedding, which is often related to low ferritin, can take six months or longer to show visible improvement because of the hair growth cycle. Tracking fatigue and brain fog symptoms over time in an app like PeriPlan can help you see the gradual improvement and correlate it with your supplementation timeline, which provides useful information to bring to your doctor at follow-up appointments.

What to Look for on the Label

The most important number on an iron supplement label is the elemental iron content, not the total weight of the compound. A label that says 324mg of ferrous sulfate contains about 65mg of elemental iron, since ferrous sulfate is roughly 20 percent iron by weight. Ferrous bisglycinate tends to have clearer labeling of its elemental iron content, which makes it easier to know what dose you are actually getting. Look for third-party testing verification such as NSF, USP, or Informed Sport certification, which confirms that the product contains what it says and has been tested for contaminants.

When to Talk to Your Doctor First