The DSM-5 is the fifth edition of The Diagnostic and Statistical Manual of Mental Disorders. It is the official manual of the American Psychiatric Association. Its purpose is to provide a framework for classifying disorders and defining diagnostic criteria for the disorders included. The DSM-5 is a specialist document used primarily by mental health researchers and health care providers in the United States. After years of research to confirm the existence and hormonal triggers of PMDD, it was finally added to the DSM-5 in 2013.
You may be interested to know that PMDD was also added to the ICD-11 (International Statistical Classification of Diseases and Related Health Problems) in 2019 - making PMDD a legitimate diagnosis worldwide.