Systemic Nickel Allergy Syndrome (SNAS): Symptoms, Diagnosis, and Latest Treatments in 2025

# Systemic Nickel Allergy Syndrome (SNAS): Symptoms, Diagnosis, and Latest Treatments in 2025

## Summary

Systemic Nickel Allergy Syndrome (SNAS) is an allergic condition characterized by both contact dermatitis caused by nickel exposure and systemic symptoms triggered by ingestion of nickel-rich foods. Nickel, a ubiquitous metal found in soil, water, food, and many everyday items, can cause allergic reactions in sensitized individuals. SNAS manifests with a combination of skin symptoms such as eczema and dermatitis, along with gastrointestinal complaints including bloating, diarrhea, nausea, and abdominal pain. Diagnosis of SNAS typically involves a positive nickel patch test, which confirms sensitivity to nickel, and an oral nickel challenge test conducted after a period of nickel-free diet to observe symptom recurrence. The oral challenge helps to confirm the systemic nature of the allergy. Patients with SNAS often report persistent skin lesions that do not improve with avoidance of direct skin contact alone, indicating systemic involvement.

## Benefits

Treatment primarily focuses on dietary management by restricting foods high in nickel, such as certain cereals (oats, barley, corn, soy), fruits (apricot, cherry, grape, pear, fig, melon, banana, plum, kiwi), vegetables (broccoli, onion, spinach, lettuce, asparagus, cauliflower), meats, fish, seafood, and some sweets like cocoa and chocolate. Studies have shown that a nickel-restricted diet can significantly reduce both cutaneous and gastrointestinal symptoms. However, adherence to such diets can be challenging due to nickel’s widespread presence in foods and the environment.

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