I was on bisoprolol 10mg as diagnosed with innapropriate sinus tachycardia had to drop to 5mg was making me ill what other meds for ist?

Take another look.: Perhaps taking another look would be fruitful. Heart rate is influenced by multiple neuroendocrine factors, some of which are uncommon. A careful history, physical exam, and specific blood and urine tests might provide an answer as to the cause; this could be helpful in providing a clue as to the therapeutic options. An experienced internist, cardiologist or endocrinologist might be helpful.