My husband gets hives at night not every month but sometimes up to three times a month.  THey only come at night and subside after two benedryl tablets but the time it takes for them to subside is increasing.  We cant identify a trigger, is there anything other than benedryl to relieve them when they occur?
You are very right in expressing that you are not able to find triggers. In fact it's only the sufferer who can find the reasons better instead of tests and machines. Anything on this planet can be an allergen to someone. Modern antihistamines (like Been Chat Doctor.  Now that it's getting resistant slowly or say, losing effect, you have to find out better option. Ayurveda has the answer. Turmeric powder + Need leaves powder + Sugar candy powder in 1