It was written mainly by Lennon and credited to Lennon and McCartney. Released in their album Help!. This is a tricky song in the sense that many of us fans love it but it is not a favorite of the band. Neither John nor Paul were mad about this song, basically considering it a filler song, :
Sometimes we didn't fight it if the lyric came out rather bland on some of those filler songs like It's Only Love. If a lyric was really bad we'd edit it, but we weren't that fussy about it, because it's only a rock 'n' roll song. I mean, this is not literature.
Paul McCartney
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