Hi Doctor, I am having severe constipation for almost two months which resulted in very hard stool alongwith blood. I went to a physician who further referred my to a surgeon who has diagnosed that I am having fissure ano. He advised shield ointment to be applied locally alongwith O2 tablet. Also I was told to have isabgol husk at night. The ointment is working but O2 tablet i am not sure as I am still having severe constipation and burning sensation and pain after motion. Kindly tell me the relevance of the O2 tablet.