Hibiscus tea is pretty harmless, mostly used for its nutrients and taste, not so much for medicinal purposes. Tea is also not very potent, not as potent as a tincture, and less potent by far than a standardized extract. Is good for colds and coughs, but again, mostly for flavor and calming. Any problems that a herb would have would come with overuse or constant use, not just one occasion, unless, of course, you're drinking toadstools.