Encouraging text messages help people to quit smoking, finds study published in The Lancet medical journal.
British doctors recruited 5,800 smokers and randomly assigned them either to a group that received specially-tailored SMSes or to a control group.
The first group received five messages a day for the first five weeks and then three per week for the next six months.
The messages -- developed with the help of smokers themselves -- gave advice for keeping weight off while quitting and encouraged participants to persevere.
"This is it! - QUIT DAY, throw away all your fags [cigarettes]," was an example of what they received on the day they started cessation. "TODAY is the start of being QUIT forever, you can do it!"
Volunteers in this group also had a personalised system in which, at times of need, they got help by texting the word "crave" or "lapse".
They would receive this kind of reply: "Cravings last less than 5 minutes on average. To help distract yourself, try sipping a drink slowly until the craving is over."
In response to the "lapse" text, they would get this response: "Don?t feel bad or guilty if you?ve slipped. You?ve achieved a lot by stopping for a while. Slip-ups can be a normal part of the quitting process. Keep going, you can do it!"
In contrast, smokers in the control group received bland SMSes every fortnight thanking them for taking part or requesting confirmation of contact details or other messages that were unrelated to smoking.
Throughout the trial, volunteers in both groups sent off samples of their saliva by post.
These were tested for cotinine, a chemical found in tobacco, to see if they were still smoking or had given up.
After six months, 10.7 percent in the SMS support group had been continuously abstinent, but this was only 4.9 percent in the control group. Success was similar across all ages and social groups.
The researchers say the "txt2stop" trial demonstrated a powerful, low-cost tool for combatting smoking addiction -- and one that could be adapted around the world.
In 2009, more than two-thirds of the world?s population owned a mobile phone and 4.2 trillion text messages were sent.
"Text messages are a very convenient way for smokers to receive support to quit," said Caroline Free of the London School of Hygiene and Tropical Medicine, who led the experiment.
"People described txt2stop as like having a 'friend' encouraging them or an 'angel on their shoulder'. It helped people resist the temptation to smoke."
Txt2stop is the latest investigation of mobile-phone messages as medical tools.
In a study published last November, HIV-infected patients in Kenya who received text reminders about taking daily AIDS drugs were 12 percent likelier to achieve full adherence to their drug regimen than counterparts in the non-text group.
Smoking kills more than five million people each year, and two out of three British smokers have said at some point they would like to quit, according to figures quoted in the study.
Previous research has found that SMSes encourage smoking abstinence, but these experiments only lasted six weeks, as opposed to six months, and the results were self-reported by the volunteers, rather than checked in lab tests.