Brief Answer: Is this because of muscle pain or stiffness? Detailed Answer: Hi and thank you so much for this query. I am so sorry to hear about this difficulty that you have reported moving around. Perphenazine is an anti psychotic medication that can cause movement disorders like tremors, twitches, uncontrollable involuntary muscle movements etc. This drug in no way causes the fear of heights. I will like you to describe exactly what this difficulty is. If it is a problem related to muscle movements then this drug may be the cause. However, the sudden onset of these symptoms make it less likely to have been caused by this disorder. The family history raises so much concern about Parkinson's. Parkinson is a known cause of movement difficulties and could be at the origin of this. What I will suggest is that he should get fully evaluated. These symptoms may not be too suggestive of a drug side effect after such a long time and of sudden onset. Other possible causes like Parkinson's which runs in the family should be ruled out. I hope this helps. I wish him well. Thank you so much for using our services and feel free to ask for more information and clarification if need be. Dr. Ditah, MD.

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