Odor normally occurs when you haven’t cleaned your drain. It comes from the buildup of scum and debris in the drain. To get rid of the odor, boil some water and then mix in one cup of baking soda and one cup of vinegar. Pour the mixture down the drain and wait about 10 minutes and then pour water down the drain to wash out the mixture. Doing this will get rid of the odor and clean your shower drain. You should try to clean your shower drain once every month. Cleaning your shower drain once a month helps to prevent the odor from coming back.