Anaemia is currently still a global health problem. About 26.8% of Indonesian adolescents suffer from anaemia. Most of them do not realize that they suffer from anaemia, neither do they understand the effects of it; this, therefore, warrants a need for health education by utilizing online technology. The purpose of this study was to determine the impact of health education through online learning on the knowledge level of adolescents about anaemia. This study is quasi-experiment research with a pretest–posttest using a control-group design. The sampling technique used was stratified random sampling, with a total of 36 respondents who were divided into control and intervention groups. The respondents were screened using the Haemoglobin Test Strip Monitoring System and data were collected using a questionnaire. Data analysis in this study used the Wilcoxon and Mann–Whitney tests. The results showed that there was an increase in the mean knowledge value of anaemic adolescents (p < 0.05) based on the Wilcoxon test results, while based on the Mann–Whitney test, there was no difference between the intervention and control groups (p > 0.05). Health education through online learning media can be given to adolescents because through these media, adolescents can quickly get information related to anaemia anywhere and anytime, and there is a need for active interaction during activities.
Keywords: online learning, health education, anaemia, adolescents