Randomized clinical trial to assess pain and bruising in medicines administered by means of subcutaneous and intramuscular needle injection: is it necessary to have needles changed?

UNLABELLED This clinical trial aimed at comparing the intensity of pain and bruising by subcutaneous and intramuscular injections using and retractable fixed syringes and needles and syringes with no needles combined, at a public hospital in Sao Paulo, for six months. We evaluated the perception of pain in case of intramuscular (n=1000) and subcutaneous injections (n=240). In subcutaneous application, bruise formation was also verified. Pain and bruising scores were higher in the group with no needles combined (p<0.001) and (p<0.029), respectively. The test power in relation to the pain scale of was 0.98. The use of retractable fixed needles is recommended in the application of subcutaneous and intramuscular injections. CLINICAL TRIAL REGISTRATION NUMBER NCT01271608.