The investigators purposes are to define the prevalence of omeprazole resistance gastroesophageal reflux disease (GERD) in systemic sclerosis (SSc), to compare the efficacy of omeprazole in combination with algycon versus omeprazole in combination with domperidone on the severity of reflux symptoms in omeprazole resistant GERD in SSc, and to compare the efficacy of omeprazole in combination with algycon versus omeprazole in combination with domperidone on the frequency of symptoms in omeprazole- resistant GERD in SSc.