What Are the Symptoms of Iron Deficiency in the Human Body?

Iron deficiency is a common health issue that affects specific groups more than others, including menstruating women, pregnant and breastfeeding women, infants, children, adolescent girls, and female athletes. When the body lacks sufficient iron, it first draws from its internal reserves. If not replenished, this leads to the depletion of iron stores and may result in iron deficiency anemia. Symptoms can vary depending on the severity of the deficiency and the individual’s overall health. In mild or moderate cases, a person might not notice any symptoms.

Common Symptoms of Iron Deficiency

Unusual Fatigue and Weakness

Fatigue is one of the most frequent signs of iron deficiency. Iron is vital for producing hemoglobin, the protein in red blood cells that carries oxygen throughout the body. When levels are low, the muscles and tissues receive less oxygen, leading to low energy levels, weakness, and difficulty concentrating. If tiredness persists even after rest, it's advisable to check iron levels.

Headaches and Dizziness

While many conditions can cause headaches, frequent or persistent headaches may signal an iron deficiency. Reduced oxygen supply to the brain increases blood flow, putting strain on blood vessels and causing headaches and dizziness.

Pale and Dry Skin

Hemoglobin gives blood its red color and contributes to a healthy skin tone. Low iron levels can lead to noticeable paleness in the face, gums, nail beds, or lower eyelids. Dry skin may also occur as the body prioritizes oxygen delivery to essential organs over the skin.

Brittle or Spoon-Shaped Nails

Although less common, brittle nails that break easily may indicate iron deficiency. In more advanced cases, nails can become concave—a condition known as koilonychia.

Swollen or Sore Tongue and Mouth

Changes in the tongue, including swelling, soreness, or a smooth texture, may be related to iron deficiency. Cracks at the corners of the mouth can also occur.

Restless Legs Syndrome (RLS)

Some individuals with iron deficiency may develop RLS, characterized by an uncontrollable urge to move the legs, often accompanied by discomfort and sleep disruption.

Shortness of Breath

Low iron levels can reduce the blood's oxygen-carrying capacity, causing shortness of breath even during everyday activities.

Heart Palpitations

Heart palpitations, or an irregular heartbeat, can result from iron deficiency, although other factors like stress or physical activity might also play a role. While usually not serious, persistent palpitations warrant medical evaluation.

Additional Symptoms

Other signs include anxiety, cold hands and feet, increased susceptibility to infections, and cravings for non-food substances—a condition known as pica.

Iron Deficiency Symptoms During Pregnancy

Pregnant women require higher amounts of iron to support increased blood volume and oxygen delivery to the fetus. Without adequate iron stores, they may experience symptoms like fatigue, pale skin, chest pain, cold extremities, and even pica—craving substances like ice, dirt, chalk, or paper.

Iron Deficiency and Depression

Iron deficiency has been linked to depression. A 2018 study published in the Journal of the College of Physicians and Surgeons found that 73% of individuals with diagnosed depression also had iron deficiency anemia. The severity of depressive symptoms correlated with the degree of iron deficiency.

Iron Deficiency and Hair Loss

The connection between iron deficiency and hair loss remains inconclusive. Iron is essential for enzymes like ribonucleotide reductase, which supports cell growth. Hair follicles may be sensitive to low iron, but not all studies agree on a direct link. There's also no clear evidence that iron supplements help hair loss in people who aren't anemic but have low iron stores.

Iron Deficiency and Heavy Menstrual Bleeding

According to the UK's National Health Service (NHS), women with heavy menstrual bleeding are at higher risk for iron deficiency. Symptoms may include prolonged bleeding lasting over a week, pelvic pain, reduced ability to perform daily tasks, and typical signs of anemia like fatigue and shortness of breath.

Impact of Iron Deficiency on the Fetus

Insufficient iron during pregnancy may increase the risk of premature birth or having a baby with low birth weight (under 2.5 kg). Premature birth is a leading cause of infant mortality, and affected infants face greater health risks in infancy and childhood.

Why Iron Is Important for the Body

Iron plays a crucial role in healthy growth, the formation of hemoglobin and myoglobin (which delivers oxygen to muscles), and energy metabolism. It's also involved in producing certain enzymes, hormones, bile acids, and neurotransmitters.