The main thing that makes folks feel sick isn't mold, although that may do it, too. Mold tends to cause more sino-nasal-respiratory side effects, from what I've read.

Nausea results from the fact that your body's responding to the cannabinoids with its CB receptors, which are in the brain and all over the digestive system and other parts of the body, too, including the areas in your brain and correlating areas in your stomach that both suppress and cause nausea. Feeling sick after smoking isn't an unusual report at all. Plenty of people, especially first-timers or returnees after breaks, even throw up. Coughing can make that worse, as can food, alcohol, or panic during the adrenergic-vasoconstriction phase after smoking. Some strains have much stronger anti-nausea effects than others, and some, I'm convinced after being here for a year and a half and reading the reports of nausea-vomiting I have, can make nausea much more likely to happen.

This is why it's not just broadly available across the board, Bogart. Because while it is natural it's not by any means 100% beneficial to all people, even recreationally, clearly.