Tonya Crowder, Marlene Durham, and Demetrius Onuaguluchi were indicted last week in federal court.
According to the indictment, the clinics only accepted cash, and many of the patients were paid by so-called "crew leaders" to seek prescriptions for controlled substances like oxycodone and hydrocodone.
Prosecutors say patients would get their prescriptions filled at Wellwise Pharmacy, which is owned by Onuaguluchi, and "crew leaders" would then take possession of the drugs to "divert to street-level distribution."
The operation is alleged to have taken place between 2021 and 2025.
According to the indictment, Westheimer Clinic in west Houston was co-owned by Marlene Durham and a licensed doctor, who wasn't named in the indictment.
THC Clinic in southwest Houston was co-owned by Tonya Crowder and the same unnamed doctor.
The indictment alleges the doctor provided Crowder, Durham, and others with his DEA registration number so that they could authorize prescriptions.
A spokesperson for the U.S. Attorney's Office didn't return an email asking if the doctor would face charges.
"Americans should never have to wonder whether a prescription was written because it was needed or because someone saw an opportunity to profit," DEA Administrator Terry Cole said at a press conference announcing the charges Tuesday.