The crash happened near the Chinese graveyard on Vichitsongkram Rd, not far from the Makro store, about 1.30 pm.
Police said the driver of the six-wheeled truck told them he had taken medicine at lunchtime, which caused him to fall asleep at the wheel while he was delivering a load of sand from Phuket Town to Patong.
His truck crossed the road to the opposing carriageway, where it smashed into a motorcycle and a car.
The motorcyclist and two people in the car were injured, although not seriously - They are being treated at Phuket International Hospital. The truck driver is now in Tung Tong Police Station in Kathu district.