Objective: To evaluate if self-administered 900 mg Isonicotinic Acid Hydrazide (INH) vaginally reduced pain during the insertion of the Levonorgestrel releasing intrauterine system (52 mg LNG-IUS) among women with elective caesarean section (CS).  Methods: This was a double-blinded, single-center, randomized controlled trial. 12 hours before 52 mg LNG-IUS insertion, 220 women were randomly allocated to receive INH 900mg vaginaly or placebo. The mean pain score during 52 mg LNG-IUS insertion was our primary endpoint. Mean pain scores during tenaculum application, uterine sounding, and 10 minutes after insertion were our secondary outcomes, as were ease of insertion, satisfaction score, need for further analgesics, and side effects. On a 10-cm VAS scale, IUD insertion ease was assessed from 0 to 10, with 0 signifying very easy insertion and 10 denoting extremely difficult insertion. Fisher 's exact test and Chi square test were used for comparison between groups, as appropriate. The student t test was used to compare quantitative data between the two groups. Results: When compared to the placebo group, the INH group experienced significantly less pain during IUD insertion (4.13± 0.98 vs. 6.22± 0.895; P<0.001) and 10 minutes after insertion (2.63 ± 0.82 vs. 4.52 ± 0.79), easier IUD insertion (2.67 0.83 vs. 5.56 0.87; p0.01), and higher satisfaction (7.25 ± 0.77 vs. 4.74 ± 0.87). When compared to the placebo group, the INH group required fewer extra analgesics (P<0.001). The two groups had similar side effects.  Conclusions: In women who had solely delivered via elective CS, self-administered 900 mg INH vaginally before 52 mg LNG-IUS insertion reduces pain scores during LNG-IUS insertion, making insertion easier and increasing women's satisfaction, with tolerable side-effects.