As far as we are aware there is normally no problem with taking Bach remedies alongside other medicines. The active ingredient in a flower remedy is an energy from the plant, not a physical substance, so it will not interfere with the physical action of the other medicine. Nor will the other medicine stop the Bach remedy from working.
A point of caution concerns the alcohol used to bottle and preserve the remedies. While the amount of alcohol in a single diluted dose is minute, you should check with your prescribing doctor, pharmacist or health advisor before taking an alcohol-based Bach remedy if you have any doubts or if you have been advised to avoid alcohol, or if there is any contraindication with alcohol and your prescribed medication.