Introduction: The use of hand warmers in Hong Kong during cold weather has become increasingly popular. Iron powder is one of the ingredients. We report the first cases of ingestion of hand warmer contents. CARE REPORTS: Four elderly patients ingested the contents of hand warmers. All had no or mild symptoms, one had radiopaque particles in the stomach, two showed transiently increased serum iron concentrations (within the reference range), and all recovered with only supportive care.
Discussion: These hand warmers contain a mixture of iron powder, activated charcoal, vermiculite, sodium chloride, and water. Iron powder accounts for about 50% of the weight (range 95-120 g). There are no reports of elemental iron or iron oxides ingestion causing iron toxicity and no published data on the absorption, elimination, adverse effects, or toxicities in humans after unintentional ingestion of hand warmer contents. A single oral dose toxicity test of hand warmer contents (2 g/kg) resulted in no toxicity or deaths in ten rats. Ingestions of one hand warmer packet or less can be treated with observation and supportive care as needed.
Conclusions: Although this case series is small, the lack of toxicity is consistent with animal studies. It appears unlikely that significant toxicity will occur after the ingestion of one hand warmer packet. The ingestion of larger amounts might lead to iron-related toxicity and may justify more aggressive management. Proper labeling by local distributors may prevent further unintentional ingestions of these non-food products.