Hello, Thanks for writing to Health Care magic, I am Dr , Muhammad Ahmad , I have read your question closely, I understand your concern and will be helping you with your health related problem. There are a few side effects which can be there when you have just started taking the Losartan it can be Bp drop, dizziness, reactionary heart rat increase, angioedema etc. If you have got this side effect in my opinion you should not be anxious and shouldn t panic, this is expected to get better with time. I would suggest you to keep using the medication according to your doctor s advise and as body gets used to the drug in your system you heart rate will get seetled up along with. If this doesn t get better in 3-4 days then you can discuss this with your doctor he can suggest you some other medcication or start a losartan in combination with a beta blocker to check the heart rate. I hope this answered your question, If you have more queries I am happy to answer you. Regards. Dr.Muhammad Ahmad