It might be best for now to give her the antihistamines just to relieve it for her. I've had hives and it's awfully itchy and I lived on phenergan tablets for 3 days till it went. She wont have to take them for long, just long enough to ease the itchiness of them. usually hives are a quick reaction to something - it will have been ffrom something she's eaten in the days prior to breaking out. When I had it, it was because I'd brought a 2lt carton of chilled fresh orange juice and drank a heap of it because it was so nice - turns out it was the preservative in the orange juice! is there anything she's eaten that's unusual or even eaten anything excessively? MIL got hives once from eating a heap of prawns.