An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Holroyd KA, Penzien DB, Cordingley GE.Holroyd KA, et al. Among authors: penzien db.Headache. 1991 May;31(5):333-40. doi: 10.1111/j.1526-4610.1991.hed3105333.x.Headache. 1991.PMID: 1830566Clinical Trial.
Maizels M, Smitherman TA, Penzien DB.Maizels M, et al. Among authors: penzien db.Headache. 2006 Oct;46 Suppl 3:S98-109. doi: 10.1111/j.1526-4610.2006.00561.x.Headache. 2006.PMID: 17034404Review.
Smitherman TA, Maizels M, Penzien DB.Smitherman TA, et al. Among authors: penzien db.Headache. 2008 Jan;48(1):45-50. doi: 10.1111/j.1526-4610.2007.00974.x.Headache. 2008.PMID: 18184285Review.