Hello, I have gone through your query and understand your concern. You are using Evening prime rose oil for hot flashes. Even it helps your for hot flashes. There is not study showing a direct interaction between Letrazole and Evening Prime rose oil. Further Evening prime rose oil is a herbal product and is found to be safe in most of circumstances. But the effect of letrazole may be decreased by these herbal products and also this can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Thus you should discuss with your Oncologist before taking any drugs or herbal products. Further he may recommend some other treatment for hot flushes. Hope this helps. Please write back for further queries. Wishing you good health.