The TV doctor - most famous for his role in Channel 4's Embarrassing Bodies series - has said that he has been "destroyed" by the comments made by unidentified people on the internet.
Jessen had been falsely accused of selling drugs online, as well as searching for unsafe sex, reports The Sun.
He said: "I've been plagued by these problems for two years now. I don't know whether it's one person who I've offended or others who are out to get me.
"My bosses at Channel 4 quickly realised it was fake but I was really destroyed."
Jessen is currently writing a "growing-up guide" for teenagers, and doesn't want the claims to ruin his work to promote safe sex.
He added: "I'm proud of my work getting the message across about safe sex. I don't want that undone."