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Iron supplements on alternative days may be as effective as daily with fewer adverse effects

Many patients find it difficult to take oral forms of iron due to GI adverse effects. This study gave single doses of 60 mg iron on consecutive days versus the same dose on alternate days.The participants were described as women who were iron depleted and were followed for 14 days.

The outcomes measured in fractional iron absorptions were 16·3% (9·3, 28·8) in the consecutive-day group versus 21·8% (13·7, 34·6) in the alternate-day group (p=0·0013). Eight (38%) of 21 patients in the consecutive-day group and five (26%) of 19 in the alternate-day group reported gastrointestinal adverse events (all were grades 1–2; grade 4 is the most severe), and that number would probably have increased if constipation had also been recorded.

Unanswered questions are: will this apply to people with more severe anaemia and will alternate day dosing lead to significantly decreased adherence.