Introduction: Intravenous therapy is indicated for many reasons. A significant number of patients admitted into hospital receive some forms of intravenous therapy through peripheral venous cannula, which is a common procedure carried out in hospital to allow rapid and accurate administration of medication. However, the intravenous cannulation can have undesirable effects, the most of which is phlebitis, which is due to mechanical, chemical or infectious cause. Method: In this study quasi-experimental research approach was used. Non probability purposive sampling technique was used to select the sample from the selected hospital. The research design adopted for the study was pre-test, post-test control group design. In the present study a sample of 60 hospitalised patients and who met the inclusion criteria was selected from the target population. In this study the instruments used are baseline Performa, structured interview schedule to assess the subjective symptoms and observation scale to observe the objective symptoms. Result: In experimental group post test mean score 1.10, SD was 0.71 respectively. In control group post test mean score 2.53, SD was 0.78 respectively. The obtained value 7.454 statistically was significant at 0.001 levels. So research hypothesis was accepted. So there was significant difference between post intervention phlebitis among the experimental group and control group. Discussion: In the research study findings revealed that Glycerin Magnesium sulphate dressing is highly effective in decrease phlebitis level to the patients.