Are supplements of big companies danger? (if you obey to the instructions)?

If you do decide to take any its not illegal but still be cautious. I had a teacher quote somebody in a lecture once and she said that with medicine of any type including over the counter supplements, "if it can help you it can hurt you." I think that is a good word to the wise to be smart. There is no such thing as some cure-all magical pill that will make someone miraculously thin overnight or end all of their anxiety. So if you do decide to take the supplements, keep your eyes open and watch for side affects and do your research on whats in it. Sometimes after you do that it doesn't seem like all that great of an idea anymore.