FDA and MedImmune have revised the WARNINGS, OVERDOSAGE, and POST MARKETING EXPERIENCE sections of the Synagis (palivizumab) label to provide clarification on the risk of anaphylaxis (hypersensitivity) based on worldwide post-marketing experience. Very rare cases of anaphylaxis have been reported following re-exposure to Synagis. Rare severe acute hypersensitivity reactions have also been reported on initial exposure or re-exposure to Synagis. The labeling was also revised to reflect that adverse events after a sixth or greater dose of Synagis are similar in character and frequency to those after the initial five doses.