According to the study, up to one in six are left in pain because they fire off so many messages.
Symptoms include aches and strains in the hands, wrists, arms, shoulders and neck.
The Chartered Society of Physiotherapy said 16 per cent of 16 to 24 year-olds have had TMI or Text Message Injury.
It is claimed that 34 per cent of 16 to 24-year-olds notch up 20 or more a day.
The CSP said the repetitive thumb and finger action can lead to hand and wrist injuries - while holding a mobile too far away while typing puts pressure on the arms and shoulders.
"Mobile phones are not designed for excessive texting," The Sun quoted the society, as saying.
It advised: "Keep messages short and use abbreviations and predictive text. Try to restrict text sessions to five or ten minutes and avoid holding the phone if you are not using it."