It is completely unsafe to consume propranolol occasionally as the withdrawal of the medication must be around 10-14 days and must be gradual. If you do consume propranolol occasionally, you will start witnessing unpleasant side effects such as vomiting, sweating, shivering, fast heartbeat, shaking, heart attack, and even death in some cases. Hence, keep your medication on a regular level or do not consume it at all.