en Pulmonology Pulmonology Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> Mustard is one of the most destructive chemical gases used in chemical warfare. Several studies showed effectiveness of inhaled morphine as a secondary treatment for the improvement of dyspnea. Therefore, this study aimed at determining the efficacy of low dose inhaled morphine for respiratory function improvement in patients who were exposed to the mustard gas.<span style="font-size:9.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> This study was designed as a cross-over double-blinded clinical trial. Patients exposed to mustard gas were randomly assigned into two groups: 1) received 0.4 mg of morphine by inhalation and 2) received 5 ml of normal saline serum as a placebo in the same manner. After a washout period of one week, the first group received the placebo and the second group received morphine for 5 days. Spirometric indices, expiratory flow peak, exercise test, severity of dyspnea, and quality of life were evaluated as respiratory function parameters. Data analysis was done using SPSS software Version 16.<i><span style="font-size:10.0pt"></span></i></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> The mean maximum expiratory flow was significantly higher among cases who used morphine in comparison with the placebo group (p<0.05). Moreover, the severity of dyspnea, quality of life, and the frequency of coughing during the day were significantly improved among the recipients of morphine (p<0.05) while the spirometric indices and exercise tolerance tests were similar between the two groups (p>0.05), but the mean peak expiratory flow (PEFR) was significantly higher among the patients receiving morphine than the placebo patients (p<0.001).<b><i><span style="color:blue"></span></i></b></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion</span></i></b><i><span style="color:blue">:</span></i> The use of inhaled morphine had a significant positive effect on the respiratory system of people exposed to mustard gas. We can use low doses of inhaled morphine to improve the respiratory function of these patients as a secondary therapy.<b><i><span style="color:#0033cc"></span></i></b></span></span></span> Dyspnea, Mustard gas, Morphine, Quality of life 575 581 http://caspjim.com/browse.php?a_code=A-10-1870-1&slc_lang=en&sid=1 Samad Ghodrati samad_md@yahoo.com 100319475328460037572 100319475328460037572 No Department of Internal Medicine, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Mohammad Memarian draria2018@gmail.com 100319475328460037573 100319475328460037573 No Department of Internal Medicine, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran shohreh Alian Samakkhah s.alian@ausmt.ac.ir 100319475328460037574 100319475328460037574 No Department of food hygiene and quality control, faculty of veterinary medicine, Amol University of Special Modern Technologies, Amol, Iran Masoud Asadi Khiavi makhiavi@gmail.com 100319475328460037575 100319475328460037575 No Zanjan Applied Pharmacology Research Center, Zanjan University of Medical Sciences, Zanjan, Iran Aiyoub Pezeshgi dr.a.pezeshki@gmail.com 100319475328460037576 100319475328460037576 Yes Department of Internal Medicine, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran