My name isXXXXX you for choosing Just Answer to help with your question.
As with any medications, there are side effects. You can have none, some or all of the below listed side effects:
dizziness, drowsiness, headache, diarrhea, constipation, excitability, weakness, anxiety, difficulty sleeping, upset stomach, rapid or irregular heart beat and/or decreased appetite.
To my knowledge, there are no known side effects of Alka-Seltzer related to the bones and or joints. Some antacids can cause osteopenia or osteoporosis, but these are ones that are aluminum based. Alka-Seltzer is not aluminum based.
I hope this has answered your question. If you have further questions regarding this, please reply to this post.
Have a great day!