When used properly, most supplements are appropriate for daily, long-term use.
A few, however, should be taken only as needed for specific, generally short-lived conditions, and others should be discontinued periodically.
Echinacea, for example, is best used at the onset of a cold or flu or when you’re around others who are ill. Once this period is over—say, two or three months during flu season—put it back in the cupboard and save it until you need it again.
Other herbs, ginseng in particular, also require periodic “breaks.” After taking Panax or Siberian ginseng for a few months, discontinue it for three or four weeks before resuming. Reputable companies will note this on product labels along with instructions such as, “Not for long-term use.” (Learn more about using herbal supplements.)
However, for the vast majority of nutritional supplements, taking them daily is both safe and appropriate.