Web giants including Facebook and Twitter are handing homophobic bullies a "free pass" to taunt victims, said the leader of the Conservative party in Scotland.
Ruth Davidson revealed she is subjected to a daily torrent of homophobic abuse online because she is a gay woman.
Around 21,000 young people attempt suicide every year over taunts about their sexuality, Davidson said.
Writing for the Daily Record in Scotland, she said: "As a politician, I get online abuse all the time. It goes with the territory.
"But as an openly gay politician, I also get a significant amount of homophobic abuse, and I feel a responsibility to challenge that.
"I don't want young LGBT people reading my timeline and thinking that that sort of language is OK. I don't want them believing that the only response is to just sit passively and take it."
Davidson said her tactic was to expose the abuse by retweeting it so it appears to followers on her own Twitter timeline.
But abusers often post abuse beneath a cloak of anonymity, making identification difficult. Meanwhile, sites including Twitter have been criticised for responding slowly to calls to tackle abuse.
Davidson said web trolls were handed a "free pass" to abuse others, as a result.
Cowards use the anonymity of Twitter and Facebook to hurl around horrendous slurs.
"We can help young people by calling out this abuse when we see it," she said. "We'd never let casual racism go unchallenged, so why is casual homophobia given a free pass?"
Davidson has faced abuse offline too. She was also heckled at a gay awards show in London for opposing same-sex marriage, two years ago.