The Coronation Street actress took the legal high of nitrous oxide while celebrating with friends at a London nightclub.
Keegan posed next to the picture printed by The People in a photo on Twitter uploaded early yesterday morning (Sunday).
She left a status reading: "Oh hell... Apparently I'm a 'crack addict' Hahahaha!! Yeah... Ok!"
Later she added: "hahaha!!! I can't look my family in the eye!! Haha. Xx.
"Still feel the effects from the weekend. Had such a good time with ma girlies. My belly still hurts from laughing!! xx (sic)."
The newspaper reports that the soap star used laughing gas with three other girls at 12.30am in the Anaya nightspot near Piccadilly Circus.
A supposed onlooker said: "Michelle and her friends had a big bottle of Grey Goose vodka, a load of shots and then this girl came around selling balloons. Michelle had one and she seemed to really enjoy it.
"She and her mates were dancing and having a great time. I was quite surprised she had a balloon. She was celebrating her birthday and she seemed really determined to have a good time."
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