Hi, thanks for using healthcare magic Lipitor is rarely associated with weight loss but it is not a known side effect of plavix. In most persons, before assuming that weight loss is a consequence of a particular medication, other conditions have to be ruled out. You should consider speaking to your doctor regarding the weight loss, investigations would include blood tests and imaging. The blood tests would initially be a full blood count, ESR (checking for inflammation in the body), thyroid function tests, kidney and liver function tests, electrolyte (calcium, potassium, sodium). The imaging would depend on the history,physical findings and the results of the blood tests. I hope this help