I started taking nexium about 3 weeks ago an I started having pain in my right knee, I tried taking it every other day but the pain still kept on.I was taking pepcid also and they both helped me with the acid reflux, but they both gave me joint an knee pain.
I believe I did hear a piece on the news - a brief bit as news usually goes, that some of the PPIs can cause joint problems. Google "side effects of Nexium". I took Nexium for 5 or 6 years and each day was misery with uncontrollable diarrhea, and pain. I am almost certain that there is a connection. It has many side effects, but I no longer have my pharmacy print-out of the side effects listed. My doctor told me Prevacid would not cause severe colitis, but it did. My GI doctor said it could, and I googled "Prevacid side effects" and found a Mayo Clinic article which stated that not only Prevacid, but Prilosec, and the other PPI drugs could in certain people cause severe colitis lasting for weeks. Different people have different side effects, some people have no side effects to the the same drug.
Nexium is suppose to be a cleaner version of Prilosec. I have tried all of the acid blockers and Nexium is my last resort before surgery is necessary. While on Prilosec, I couldn't lift a dumbbell which wasn't good because I worked in a Lady's gym. Nexium...I have been on this for 6 years now and the only side effect I have is diarrhea. My gastroenterologist does not seem to be concerned because the Nexium is working for me. Nexium is not suppose to effect the joints. Have your sister talk to her doctor. He may want to do some tests on her knee. It could be other issues.
In some cases Nexium can cause muscle weakness that could be interpreted as joint pain. You sister may want to discuss the problem with her physician.
I doubt that "NEXIUM" has anything to do with your sisters knee pain. You can refer to the package insert if you look up the medication..