GPs have been warned to obtain written consent before giving iron infusions, amid ongoing complaints from patients about unexpected skin stains.

The Medical Board of Australia says it is hearing “recurring complaints” from patients who have received large brown stains at the infusion site after intravenous iron leaked into the surrounding tissue.

Many of the patients say they were not told about the risk of receiving the stains, which are permanent and usually appear on forearms.

The board says in these cases, the quality of patient consent often ranged from “exemplary to non-existent”.