Is serapepase safe to use?

Not much data. Serrapeptase, serrapeptidase, or serratiopeptidase. It is derived from a microorganism in the intestines of silkworms, serratia e15, and is a proteolytic enzyme. The worms use it to dissolve their cocoon. It has been used for about 25 years in japan, mostly for pain and inflammation. There is very little safety data on it, but there are some reports of lung inflammation, so talk with your doctor.
Serrapeptidase. I did a medline search and found primarily animal data: serrapeptidase is a topical proteolytic enzyme, ie it helps remove non-living tissue and reduces inflammation. It seems to be effective in rats. I didn't find any reliable information regarding safety. It's marketed on the internet as "a miracle enzyme". I'm not sure why you would want to experiment on yourself?