I have been on propranolol 40mg tablets for 5 years regularly for anxiety. I have overdosed on them probably about 8 or 9 times. The first one I took 14, it was for self harm not to CTB. But I was sent to resus due to having prolonged QT interval on my ECG. The next few varied dosage and side effects, it all depends on the person, what you take it with and every single time is individual. The most I have taken has been around 45...side effects were severe bradycardia, chest pain and tightness, shortness of breath, dizziness, wheezing sometimes and psychiatric symptoms like hallucinations etc...so all im gonna say is everyone reacts differently and it also depends on the half-life of the propranolol ie the type of tablet!