Suu Kyi, 76, who has been detained on various charges since her overthrow in a Feb 1 military coup, did not have the coronavirus but felt ill having not travelled in a vehicle for a long time, lawyer Min Min Soe said.
The popular Nobel Peace Prize winner has spent about half of the past three decades in various forms of detention over her non-violent struggle against dictatorship and her health is closely watched.
"It is not serious sickness... She suffered car sickness. She cannot stand that feeling and told us she wanted to take a rest," Min Min Soe told Reuters.
Suu Kyi's only communication with the outside world has been through her legal team, which says its access to her is limited and monitored by authorities.
She is on trial in the capital Naypyitaw over charges that include illegal importation and possession of walkie-talkie radios and violating coronavirus protocols.
She has been accused of accepting big bribes and has been charged with unspecified breaches of the Official Secrets Act in a separate and more serious case, which is punishable by up to 14 years in jail.
Her lawyers reject all of the allegations.
Khin Maung Zaw, who heads her legal team, said Suu Kyi could not take the stand on Monday and the judge consented to her absence.
"She seemed to be ill, sneezing and said she was drowsy. Therefore the lawyers talked only briefly with her," he said in a text message.