Evaluation of Symptoms When a subject comes for the first consultation (randomization week), he/she will be given a 4-point scale questionnaire (see Appendix II) to evaluate his/her own symptoms (pruritus severity and number of wheals). This will be completed once every evening for a week prior to the 4-week treatment period. The pruritus severity score and the number of wheals during this run in week will be averaged and used as the mean baseline score. The summation of mean pruritus score (MPS) and the mean number of wheals (MNW) will be the mean total symptoms score (MTSS) for the baseline period. Medical investigator will also evaluate the subject's global symptoms severity (GSS) at the first consultation (randomization week) and second consultation (at the end of week 4).