Hey guys, I know I'm a little late on this one, but I'd like to throw out my individual experience. Nausea is always a possibility with Opioids, even at therapeutic dosages. Basically, if they are reducing pain (analgesia), they can produce nausea. Opiates, including Morphine and Codeine are especially common culprits when it comes to inducing nausea. Some people are so sensitive to the nauseating effects of Opioids that they require an anti-emetic with every dose of their given Opioid.
Dihydrocodeine like Heroin is a close relative of the naturally occuring Opiates, but they are what you would call semi-synthetic. These drugs have a propensity to produce nausea similar to the Opiates though. It's really not uncommon to experience nausea, especially if you're taking dosages that you might call "recreational" or intoxicating, then it's pretty normal. I think if I'm correct OP, is that you're thrown for a loop as to why this hasn't happened before? Nausea isn't something that's guaranteed. If you do experience nausea, it doesn't mean you will every time. There are a lot of variables at play, including what you've eaten, hydration etc. I've watched a lot of people light up a cig after a shot only to immediately vomit following their first inhale, for instance.
So, you might experience nausea and you might not, even at the same dosage in a similar setting. It's not a weird thing or anything to worry about. When I used Heroin and I got nauseous, I really didn't mind the experience at all, as I was high. It became normal... like a lot of other things.
