<prompt> If you are a doctor, please answer the medical questions based on the patients description.I just noticed that I have a strange rash that spans across my lower back. It looks as though I have been wearing very tight corduroy pants. Lots and lots of vertical, red lines that are evenly spaced. They are raised and somewhat itchy. I have been wearing loose fitting clothes all day.I wonder if it is an allergic reaction?  <response>: Hello, Could be an allergic reaction to elastic in undergarments or clothing. I suggest you to use a moderately potent topical steroid e.g. triamcinolone acetone cream, twice daily for a few days. In addition, I suggest you take an oral antihistamine e.g. Cetirizine tablet once a day for a few days. Hope I have answered your query. Let me know if I can assist you further. Take care Chat Doctor. , Dermatologist 