I agree with ship...
What is causing the periodontal disease remains below the gumline, and no matter what you take, in the end it will not make the condition better, but maybe cover up the symptoms. Only a proper cleaning, below the gumline, to clean out the build up and other irritants will help clear up the active disease process. Your friend could also take antibiotic's, this again will help, but only the symptoms of the disease. Anything you take would have to be taken all of the time, why not get rid of the problem at the source....professional dental cleaning.
Lastly periodontal disease is generally painless. What your friend takes to help the disease will at best cover up the home symptoms of bleeding when brushing or bad breath. But the underlying problem will still exist. At the dentist office the periodontal findings will still be the same.
Don't give your friend bad advice, suggest the problem be taken care of at the dentist office. If the Dentist finds that the patient is too difficult to care for then he can perscribe medication to calm the patient or refer s/he to a specialist.
And I just wanted to add that valerian root is not the same as valium. One is a regulated drug and the other is not, which makes a big difference in the effects of the medication.
Valium is identified chemically as 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one.
Sorry no valerian root there!