Levelling up minister Dehenna Davison has quit her government role, saying she has been "battling with chronic migraine".
Jacob Young, the MP for Redcar, has been announced as her replacement.
In a letter to Rishi Sunak, Ms Davison outlined how the condition had impacted her.
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Her letter said: "Unfortunately, for some time now I have been battling chronic migraine, which has had a great impact on my ability to carry out the role.
"Some days I'm fine, but on others it is difficult, if not impossible, to keep up with the demands of ministerial life - and the timing of such days is never predictable.
"Though I have tried to mitigate, and am grateful to colleagues for their patience at times, I don't feel it is right to continue in this role.
"At such a critical time for levelling up, I believe the people of communities like mine, and across the community, deserve a minister who can give the job the energy it needs. I regret that I no longer can.
"And, as my capacity is currently diminished, it feels right to focus it on my constituents, and on promoting conservatism from the backbenches."
Ms Davison was elected in the 2019 election at the age of 25, and was the first Conservative MP to represent Bishop Auckland since the constituency was created in 1885.
She voted against Boris Johnson in the no-confidence vote in 2022, and later supported Liz Truss in the race to replace Mr Johnson.
It was under the UK's shortest-serving prime minister that Ms Davison was made a minister in the Department for Levelling Up, Housing and Communities.
In November last year, she revealed she would be standing down as an MP at the next general election.
She has also campaigned around one-punch assault victims, after her father died having been struck once when she was a child.
Ms Davison used her resignation to praise the government's work on devolution, free ports and regeneration around the UK.
Mr Young, who was previously a government whip, was replaced in that job by South West Hertfordshire MP Gagan Mohindra.