 [ Symptoms ] can low blood pressure cause death if so how low is safe [ Disease ] unfortunately your description of a red painless flat blotch on your penis is not sufficient to make a definitive diagnosis let alone offer treatment suggestions this could be balanitis you can look this up but this is just a blind guess since there is no way to examine you over the internet if this condition does not self resolve in a few days you will need to seek a hands on medical examination