After completing his residency in ophthalmology, Paul moved to Bowling Green, Kentucky. He has held a state-issued medical license since moving there in 1993. He received his first job from John Downing of Downing McPeak Vision Centers, which brought him to Bowling Green after completing his residency. Paul worked for Downing for about five years before parting ways. Afterwards, he went to work at the Graves Gilbert Clinic, a private medical group in Bowling Green, for 10 years before creating his own practice in a converted one-story house across the street from Downing's office. After his election to the U. S. Senate, he merged his practice with Downing's medical practice. Paul has faced two malpractice lawsuits between 1993 and 2010; he was cleared in one case while the other was settled for $50,000. His medical work has been praised by Downing and he has medical privileges at two Bowling Green hospitals. In April 2020, after recovering from COVID-19, Paul began volunteering at a hospital in Bowling Green, assisting them in their response to the COVID-19 pandemic in Kentucky.