The Italy international picked up the injury during Saturday's 3-1 defeat to Lazio and will now wear a foot support for six weeks after visiting a specialist on Monday.
After that period, El Shaarawy will undergo further tests to determine when he can return to first-team action.
A Milan statement on Monday read: "Stephan El Shaarawy underwent medical tests and a specialist visit with professor Niek Van Dijk in Amsterdam.
"The player, right at the end of the match against Lazio on Saturday evening, sustained a fracture at the base of his fifth metatarsal bone in his right foot following a challenge.
"The therapy that has been established is that of conservative treatment. For around six weeks, El Shaarawy will wear a foot support and following that he will undergo further medical tests and have another check-up with professor Van Dijk before a return to physical activity."
El Shaarawy missed most of last season with a separate foot injury and had made 15 Serie A appearances this term.
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