Tony Blair would never have become prime minister if social media had existed when he was younger, he has admitted.
The former Labour leader said there would have been "bad stuff" from his days in a band, long before his political career.
Speaking during Unspun on the television channel Dave, Mr Blair described a picture from his youth appearing to show him making a rude gesture as "highly embarrassing".
He told host Matt Forde: "Let this be a warning to any young person who wants a political career.
"That is one of the very few pictures of me that is obviously highly embarrassing. Today with social media, just be careful.
"When I was in the band, if we had had social media at that time, I would certainly not have been prime minister."
Asked what people would have seen he laughed and said: "Bad stuff."
Mr Blair also spoke about his views on Britain's relationship with the United States now Donald Trump is president.
He said if he was in Number 10 now he would feel it is important to "establish a working relationship" with Mr Trump.
He said: "People always want me to criticise Theresa May over this but I think the British prime minister should always get on well with the president of the United States, if it's possible.
"It has got its challenges obviously.
"But it is important because in the end there are many, many things we are going be working on together in different parts of the world."