This is my personal experience-
I completed my B.Tech IT from MNNIT Allahabad a few years back. When I was in my second year, I contracted a serious bacterial infection and was bedridden for a month. Due to this, I faced a severe shortage of attendance. However, to take care of this, I contacted all my teachers and explained to them my case. They were all very understanding and cooperative.
But when I attended a practical class some time later, one of my teachers called me to his office due to a shortage of attendance in his lectures. I then realized that I had forgotten to contact him, and explain to him my case. Despite trying to talk to him about my problem, he refused to listen to me and sent my name to the Dean Academic’s office (along with the names of others who had a low attendance in his lecture). I tried reaching out to the HOD, but it was too late by then. Ultimately, I had to sit for the supplementary exams.
The takeaway is to be aware and not miss your lectures, unless seriously ill. But if you face something like I did, make sure that your parents get in touch with the HOD and all your teachers, and explain to them about your condition in detail. There are some teachers who do not listen to the students’ problems and arrive at hasty conclusions, beware of them.