run its course, to

run its course

To progress along something's natural course and conclude at its normal pace. (Used especially in reference to illness and disease.) Unfortunately, there's no treatment for this kind of infection. You just have to let it run its course. Don't stress about Susan's new boyfriend. I'm sure it's just a summer thing—it will run its course before she goes back to school. The president said he would rather let the economy run its course than try to manipulate it with a stimulus package.
See also: course, run
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

run its course

[for something] to continue through its cycle of existence, especially a disease. Sorry. There is no medicine for it. It will just have to run its course.
See also: course, run
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

run its course

Proceed to its logical or natural conclusion, as in The doctor said the cold would probably run its course within a week. This idiom employs course in the sense of "an onward movement in a particular path." [Second half of 1500s]
See also: course, run
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

run its course

COMMON If something runs its course, it develops gradually and comes to a natural end. If you allow such behaviour to run its course without reacting, eventually the behaviour will disappear on its own. Is this a sign that the recession has run its course?
See also: course, run
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

run its course, to

To continue to the end; until it runs out. The word course, the ground on which a race is run, was used figuratively for the continuous process of time, events, or an action from the sixteenth century on. “The yeare hath runne his course,” wrote Abraham Fleming (A Panoplie of Epistles, 1576).
See also: run
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
See also: