Occasionally, the needle is not in the subcutaneous space and blisters leading to scarring can occur. This requires a formal hearing evaluation by a qualified audiologist to determine whether any changes need to be made in the Desferal dose. Desferal usually causes high frequency hearing loss, at frequencies that would not be detected or appreciated by the affected individual. Decreased night vision is much less common but occasionally occurs. There can also be retinal changes that can only be detected by an experienced opthalmologist.
Allergic reactions can be a problem and require desensitization.
Desensitization requires hospitalization and monitoring. Once desensitization has been achieved, Desferal must be used nightly to maintain tolerance. If it is discontinued for more than 48 hours, severe allergic reactions or anaphylaxis can occur. Cartilageous dysplasia of the long bones and spine as well as decreased linear growth has been described in young children who used Desferal. High dose Desferal can cause renal problems in children and adults who have preexisting renal disease, as well as in apparently healthy individuals.