shot in the arm

plural shots in the arm

1. An injection of a drug into the arm, whether for medical or recreational purposes.
2. broadlyA stimulus; a boost in energy, morale, or well-being.

   By that agreement, President Roosevelt in 1941 gave Canada's war industry a shot in the arm.

   1944 May 1, “Canada at War: Net Profit”, in Time, retrieved 31 Jan 2017

   3 more examples

   Renzo Piano's skyscraper, which will be Europe's tallest building, may provide a shot in the arm for London.

   2011 December 30, Robert Booth, “London's Shard: a 'tower of power and riches' looking down on poverty”, in Guardian, UK, retrieved 31 Jan 2017

   The president claims the economy needs a shot in the arm now, but Republicans say the nation should not widen the deficit.

   2012 December 4, Annie Lowrey, “Republicans Balk at Short-Term Stimulus in Obama Plan”, in New York Times, retrieved 31 Jan 2017

   “You get a win and suddenly the crowd’s on your side again. It was a shot in the arm for two reasons. First, when we work together, we are stronger. Second, this isn’t a done deal.”

   2018 April 28, Dorian Lynskey, quoting James McGrory, “‘It’s not a done deal’: inside the battle to stop Brexit”, in The Guardian