You’re offline. This is a read only version of the page.
- MedlinePlus is a selected list of authoritative resources.
- MedlinePlus uses quality guidelines to evaluate Web sites. We try to ensure that the information we link to is authoritative, accurate, up-to-date, educational and available at no charge.
- MedlinePlus does not point to multiple Web sites that contain the same information, even if different organizations, associations, companies or entities are responsible for their content.
- If you wish to recommend a site, please write to the Help Desk. Because we receive so many requests, we cannot respond individually to link suggestions. At this time, MedlinePlus rarely links to sites outside the United States.