I'm not a doctor, or a medical research scientist, but from my own personal experiences, and what I've seen, Yes ... as far as being more susceptible to colds, minor sinus infections, Yes, definitely ... every useful medication has side effects, and this is extremely minor, in my opinion, and well worth the trade-off :thumbsup: ... (I also doubt it could be a serious threat to the Immune System, or they wouldn't be recommending it to AIDS patients, too) :smokin: