Well, obviously, if cow's milk makes you sick (or any other kind, for that matter), you wouldn't want to ingest a concentrated form of bovine proteins and enzymes, like whey. Some of us (most of us in the world, in fact) can tolerate cow's milk just fine. The only people that may get sick from whey would be people that are lactose-intolerant or have an allergy or other reaction to cow's milk. Something an adult would know before making cheese from cow's milk, I hope. Using whey leftover from cheese would not be any different than eating the cheese you just made that produced the whey. If you can't eat the cheese, don't eat the whey. Simple. Also, you may be sensitive to the hormones and "vitamins" that mass-production dairies use in their cows. Those are bad for everybody. If you can get "local" milk, or at least "raw" but pasteurized milk, there's less to worry about, since most small dairies tent their herd a bit more naturally.