I take 25mg Tenormin for anxiety and to help keep HR normal. Started Klonopin (clonazepam) 0.25mg daily. It makes my heart race. Why is this?

Anxiety, palpitation. if repeated Klonopin (clonazepam) challenge provokes the same symptoms then discontinue use and notify to prescriber. In addition to prescription medicines have you tried regular aerobic exercise, cognitive behavioral therapy, yoga, biofeedback training etc. to manage short anxiety without pharmaceuticals?some basic labs including thyroid function should be checked if not already done.