Background: Automatic instant messaging systems are currently a well-known smoking reduction tool for public health. However, smokers’ engagement is lacking, as many prefer to communicate with experts during the quitting period so they can receive advice on dealing with the consequences of nicotine abstinence. Therefore, this study aimed to assess the effectiveness of an interactive text messaging service at the Thailand National Quitline.

Method: The study was conducted as a randomized controlled trial. A total of 314 smokers were eligible, 153 of whom were randomly assigned to receive two-way short messages encouraging them to quit smoking. After the date of quitting, ThaiBulkSMS (SMS gateway provider) sent out 49 messages to them over 6 months. The remaining 161 participants

received traditional counseling to quit smoking for approximately 30 min. Data were analyzed by descriptive statistics, a chi-squared test, and the Friedman test.

Results: Both groups were similar in terms of their descriptive characteristics and variables related to smoking (p > 0.05). The continuous abstinence rate (CAR) of the participants in the counseling group was significantly greater than that of participants in the SMS group at 3 and 6 months (43.5% vs 38.6%; 34.2% vs 28.1%; p < .05). Moreover, we found a statistically significant difference in the CAR at 3 and 6 months between the two groups at the .05 level

(x2-Friedman= 1.34; p< .05).

Conclusion: The “interactive text message service” is an innovative intervention for Thai smokers who want to quit smoking.