One book I read said that cancer chatrooms were a bad idea. I am divided. A discussion like this one, herceptin side-effects forum, on breastcancer.com which is reputable site, as well as others on the definative site the american cancer society site www.cancer.org are helpful but to use a Yiddish expression, they can "drei your kop" which means something along the lines of 'drive you demented'.
That said, the one above on herceptin side effects is very helpful. About two people also report bad taste in the mouth as a side-effect - although I had it only once, one and off for about two weeks though - and many sore muscles in their legs and muscle spasms - I have had three but one was soooooo bad, my calf muscle was still sore for about two days afterwards.