Paul Ejner Thomsen, 42, was found driving with traces of methamphetamine and marijuana in his saliva when police stopped him on Matthew St in Nambour on September 9 last year.
He told police he had smoked meth that morning and was driving to a friend's place.
Thomsen pleaded guilty in Nambour Magistrates Court on Monday to driving with a relevant drug in his saliva and was fined $400 and disqualified from driving for one month.
Jason Troy Taylor, 47, tested to positive to a roadside drug test when he was stopped on the Bruce Highway in Woombye on November 8.
Taylor said he had used methamphetamine.