The Italian coach says the striker is ready to reproduce his finest form this term after tailing off in the second half of last season
The Italy forward was the Rossoneri's stand out performer in the first half of last season, but his form dipped dramatically after Christmas following the arrival of Mario Balotelli.
Milan kick off their Serie A season with a trip to Verona on Saturday as they look to improve on last term's third placed finish and Allegri has backed El Shaarawy to fire once again.
"Stephan is doing much better at the moment, the two goals scored in Germany, the good performance in America and the midweek goal have been good for him psychologically," the 46-year-old told reporters at a press conference.
"He’s the same player he was last season. At 20 years of age, it’s not easy to find yourself under the media spotlight as he did last season.
"He hasn’t been up to his own high standards in the last two months but that just shows that in football, every day is a new test, especially in a team like Milan which always plays to win."
The San Siro side have been quiet in the transfer market this summer, bringing in Ferdinando Coppola, Simone Ganz, Rodney Strasser and Didac Villa, after missing out on primary targets Carlos Tevez and Keisuke Honda.
But Allegri insists he is happy with the squad at his disposal and says he is letting the club's hierarchy deal with transfer negotiations, while tipping one of the club's youngsters to make an impact.
He added: "That’s up to the club (transfers) and they know what they’re doing. [Andrea] Petagna is a young player but he can give us a hand. We hope to have [Giampaolo] Pazzini back for the end of October. He’s important for us.”
Allegri also revealed that Christian Abate will start on Saturday, with Mattia De Sciglio still not match fit, while Daniele Bonera and Jherson Vergara join Pazzini on the sidelines.