Iron Supplements During Perimenopause: What You Need to Know
Heavy periods in perimenopause can cause iron deficiency. This guide covers symptoms, testing, the best iron supplement types, and how to take them effectively.
Why Iron Deficiency Is Common in Perimenopause
Heavy or prolonged periods are one of the most common and disruptive features of perimenopause. As the hormonal cycle becomes erratic, some months bring unusually heavy bleeding that can last longer than usual. This blood loss depletes iron stores over time, because iron is a core component of haemoglobin, the protein in red blood cells that carries oxygen around the body. When iron stores fall, the body cannot produce enough haemoglobin, leading first to iron-depleted stores (low ferritin without anaemia) and then to frank iron-deficiency anaemia. Either state causes fatigue, breathlessness, brain fog, poor concentration, and a general sense of feeling unwell, symptoms that overlap considerably with perimenopause itself. The overlap can lead to both conditions being underdiagnosed.
Recognising the Symptoms of Low Iron
The classic symptom is tiredness that does not improve with rest. Other common signs include pallor of the inner eyelids and lips, brittle nails that ridge or spoon, hair shedding or thinning, shortness of breath on exertion, heart palpitations, difficulty concentrating, and a craving for non-food items such as ice or clay (a phenomenon called pica). Some women experience restless legs syndrome, which has a well-established link to iron deficiency. The challenge is that fatigue, brain fog, hair thinning, and heart palpitations are also perimenopausal symptoms, so it is easy to attribute all of them to hormonal change without testing for iron deficiency separately.
Testing: What to Ask Your GP For
A standard full blood count will detect anaemia but will miss iron deficiency before it becomes severe. The most informative single test is serum ferritin, which measures your stored iron. A ferritin result in the range of 12 to 20 micrograms per litre may be technically above the laboratory's deficiency threshold but is low enough to cause symptoms in many women. Clinicians working in this area often recommend aiming for a ferritin level above 50 to 70 micrograms per litre for women experiencing fatigue and hair loss. Ask your GP for a full iron panel including serum ferritin, serum iron, transferrin saturation, and a full blood count. This gives a complete picture of your iron status.
Choosing the Best Iron Supplement
Iron supplements come in several forms with significant differences in tolerability and absorption. Ferrous sulphate is the most commonly prescribed form and has good absorption, but it frequently causes constipation, nausea, and dark stools. Ferrous fumarate and ferrous gluconate are alternatives that some women find gentler on the digestive system. Ferric forms (non-haem iron in ferric state) such as ferric maltol are newer and better tolerated but more expensive; they are available on prescription for those who cannot tolerate standard ferrous salts. Gentle iron chelate supplements such as iron bisglycinate are popular over-the-counter options that cause fewer gastrointestinal side effects while still providing meaningful absorption.
How to Take Iron for Best Absorption
Iron absorption is significantly affected by what you take it with and when. Taking iron on an empty stomach improves absorption but worsens gastrointestinal side effects for many women. Taking it with a small amount of food reduces side effects without dramatically reducing absorption. Vitamin C taken at the same time (a glass of orange juice or a vitamin C supplement) enhances iron absorption by converting ferric iron to the more absorbable ferrous form. Avoid taking iron within two hours of calcium supplements, dairy foods, tea, coffee, or antacids, all of which reduce iron absorption. Many doctors now recommend taking iron on alternate days rather than daily, as research suggests that taking a day's gap allows the gut to reset its iron uptake mechanisms and may result in better overall absorption.
Dietary Iron and Perimenopause
Food sources of iron fall into two categories. Haem iron from red meat, poultry, and fish is absorbed at a rate of around 20 to 30 percent and is the most bioavailable form. Non-haem iron from lentils, beans, tofu, dark leafy greens, fortified cereals, and nuts is absorbed at only 2 to 10 percent. Both types count toward your total intake, but the difference in absorption rate matters if your stores are genuinely depleted. Women with heavy perimenopausal periods who are vegetarian or vegan may need to pay particular attention to non-haem iron sources and absorption-enhancing strategies. The recommended daily intake for premenopausal women is 14.8 mg per day; this drops to 8.7 mg after menopause when monthly losses cease.
When to Expect Improvement and How to Monitor Progress
Iron levels do not normalise quickly. Even with good supplementation, ferritin stores can take three to six months or longer to rebuild fully, particularly if bleeding continues to be heavy. Haemoglobin and red blood cell counts recover more quickly than ferritin. Your GP should recheck your iron panel after two to three months of supplementation to assess progress. If ferritin remains low despite supplementing, a review of dose, form, and dietary intake is worthwhile. If heavy bleeding is the underlying driver, treating that directly through hormonal options or other gynaecological interventions is often the most effective long-term strategy, and worth discussing separately with your doctor.
Related reading
Get your personalized daily plan
Track symptoms, match workouts to your day type, and build a routine that adapts with you through every phase of perimenopause.