Brief Answer: Why was this dose doubled? Detailed Answer: Hi and thank you so much for this query. I am so sorry to hear about this muscle pain and the unsteadiness that you have reported. It would be very strange to hear that beta blockers cause muscle pain. This is very atypical and not commonly described with this class of medications. However, because you have used two different formulations and the symptoms seem to be almost identical, I have reasons to suspect that you may have a problem with Beta blockers. Muscle pain is more common with statins! Beta blockers are a must in heart disease especially after a heart attack or if you are having angina. I don't know for what reasons you were prescribed this drug? Was it just for the management of high blood pressure or a heart related disease? If the indication is not a direct heart disease, then switching this medication may be an option to be considered. Metoprolol prevents the normal response that occurs when we stand upright from a sitting position to prevent decreased blood flow to the brain that can cause dizziness, blur vision, lost of balance, etc. It would be nice to also check your blood pressure numbers in the sitting and immediate upright position to see what the change is and what the baseline is. If it is too low, it may be the reason for the unsteadiness but all the same does not explain why you have the muscle pain. In all, it sounds likely that you have a problem with Beta blockers. If it were okay with 12.5mg, please return to this initial dose. If the indication is not absolute like in heart disease/heart attack, consider switching to a different class of medication. I hope this helps. I wish you well. Feel free to ask for more information and clarification if need be. Thank you so much for using our services. Dr. Ditah, MD.