Before joining the White House, Kudlow vocally opposed the protectionist trade agenda that Trump promoted, but he has become a forceful advocate for the president's policies since joining the administration.
In the 1980s, he served as White House budget director under President Ronald Reagan and is still a champion of that era's conservative, supply-side economics, which calls for cutting taxes to boost growth - an ideology the Trump administration has emphatically embraced.
Kudlow was admitted to Walter Reed Medical Center, according to Trump.
Kudlow, 70, travelled with Trump for the G7 meeting over the weekend, and defended the president vigorously on television on Sunday.
'Americas Got Talent' winner Neal E. Boyd dead The opera singer - who won America's Got Talent in 2008 - has died from heart failure, according to a Monday report from TMZ . Boyd, who appeared in season 3 of the USA talent competition, passed away in Sikeston, Missouri home.
Kudlow appeared Sunday on CNN to back up Trump's complaint that he had been blindsided by Canadian Prime Minister Justin Trudeau's criticism of his tariff threats at a summit-ending news conference.
He accused Mr Trudeau for the collapse of a joint communiqué after saying he was going ahead with retaliatory tariffs on the US.
A longtime TV personality, Kudlow, 70, succeeded former Goldman Sachs president Gary Cohn who quit Trump's team in March in protest at the decision to slap steep USA tariffs on imported steel and aluminum.
"I have made it very clear to the President that it is not something we relish doing, but it something that we absolutely will do", Trudeau said.
He has acknowledged ups and downs in his life, having been addicted to drugs and alcohol before getting sober more than 20 years ago.
Senior White House economic adviser Larry Kudlow speaks during a briefing at the White House in Washington. The month he was tapped for the White House job, he co-authored an article that argued such tariffs were akin to sanctions on the United States itself.