I have been on Norvasc (Name) brand Amlodipine since 1992, making it going on 30 years now. In 2012 they said I had to go to Generic Amlodipine, so I went on it and in about 6 days I could hardly walk, I am 81. So much pain in my pelvic clear down to my knees, so I went to The University Hospital in Iowa City to try different Generic BP Meds. Every single one causes that Adverse effect within 6 or 7 days of taking them, so the Professor said it was the "filler" in the Generic causing Myalgia and if I stayed on the drug it would become a permanent disability. Note, in between every med they tried on me, they had me go back on the Norvasc Name brand for 3 days and the pain went away. So 'that was reported to the FDA by the Professor and to my RX plan. That was in 2012 and I am still on Norvasc Name brand and my insurance is still covering it. My dose is 10 mg once every morning. I have had no issues with side effects with the Name Brand. But a few weeks ago my doc put me on Metoprolol Succinate ER (Lo Pressor) to take with the Norvasc. 2 weeks into it I developed severe diarrhea and my hand swelled up and hurt bad. Turned out that it was an Interaction with my Synthroid, thyroid meds. I have no glands, surgically removed in 1986 left side and 1987 right side, due to cancer. So I had to gradually go off the Metoprolol, took only 3 days because my dose was low. The diarrhea stopped in 24 hrs after taking the half dose, the swelling in my hand mostly cleared then also, but took another 3 days to completely stop the pain in my hand. So it is important to always double check for interactions with not only medications but 'with health issues and medications. My problem now is since I only have ONE kidney and it is a partial, and also on Synthroid, so I have to take a Channel Blocker BP. Metoprolol is a Beta Blocker which interacted with my Synthroid but not with my kidney, except I became dehydrated rapidly with the diarrhea, which puts my CKD in serious danger. I am not sure either my PCP or my Nephrologist will find another BP med I can take. Currently my BP is 190/90. Some days it goes down but never lower then 160/84.