Another word of caution. Always buy drugs made by a reputable company (be familiar with the correct logo too, to avoid confusion). Cheaper and generic drugs often are not processed to the same extent to remove impurities. They may still have the correct amount of active ingredients if the country has strong legislation and enforcement. What they probably won't have the removal of the non-active impurities to the same level as the reputable companies. Without getting too technical, one example was Thalidomide (remember that?). This was a problem not because of the active ingredient, but the impurities - in particular a chemical that was a molecular mirror image of the active ingredient. Most impurities will not have this drastic effect, but who can tell? Not even the US FDA has adequate legislation about impurities, but the bigger pharmaceutical companies go through more refinement processes as a rule, "just in case".