Iron Deficiency and Skin Rash
Iron deficiency does not directly cause a visible skin rash, but it causes generalized pruritus (itching) without rash, which can lead to secondary skin changes from scratching. 1
Primary Manifestation: Pruritus Without Rash
Iron deficiency is a well-established cause of generalized pruritus without an underlying dermatosis (GPWOR), meaning patients experience intense itching but do not have a primary rash. 1
- The British Association of Dermatologists specifically lists "disorders of iron metabolism" as a cause of generalized pruritus without rash. 1
- In a prospective case-control study, iron deficiency anemia was the most common cause of generalized pruritus in patients with underlying systemic disease (25% of all cases). 1, 2
- Iron replacement therapy can lead to complete cessation of pruritus very shortly after commencement of therapy in many cases. 1
Secondary Skin Changes (Not Primary Rash)
While iron deficiency doesn't cause a primary rash, it can cause:
- Secondary skin changes from scratching and excoriation due to the intense pruritus. 1
- Structural changes in skin, hair, and nails including skin problems related to keratinocyte turnover and tissue integrity. 3
- Cutaneous manifestations such as skin pallor, but not a true inflammatory rash. 3
Clinical Approach
Check full blood count and ferritin levels in all patients with chronic generalized pruritus, even without visible rash. 1, 4
Key diagnostic considerations:
- Ferritin is an acute-phase protein and may be falsely elevated despite iron deficiency. 1
- If ferritin appears "normal" but iron deficiency is suspected, check serum iron and total iron binding capacity. 1
- Initiate iron replacement if ferritin is below 15-25 μg/L or if there is unexplained anemia or microcytosis. 1
Important Caveats
Iron overload can also cause generalized pruritus, so both deficiency and excess should be considered in the differential diagnosis. 1
- Inquire about diet (vegetarian/vegan), potential blood loss sources, and gastrointestinal symptoms in all cases. 1
- Consider testing for tissue transglutaminase antibodies if iron deficiency is unexplained, as celiac disease can cause malabsorption. 1
The distinction is critical: iron deficiency causes itching that may lead to scratch-induced skin changes, not a primary inflammatory or allergic rash. 1, 3