The three were stopped at a road checkpoint on Ban Jampa Wai-Banthung Kachai road in Phayao’s Muang district.
The suspects were identified as Ansuorn Dechawut, 29, Kanchalika Tomlar, 30, and Daranee Pholdee, 37. All tested positive to drug use.
Police also seized a 9mm pistol and 26 rounds of ammunition from the man.
The two women were charged with drug abuse while the man was charged with drug abuse and smuggling.