Smoking is associated with many health effects. However, I will stick to the effects of smoking on the skin. Every puff of a cigarette causes an influx of free-radicals. Free-radicals are unstable oxygen atoms and they steal electrons from our healthy cells. This then causes our healthy cells to become unstable. Unstable cells are linked to premature ageing, such as fine lines wrinkles, by destroying our collagen and elastin. Smoking also reduces blood flow, depleting oxygen to the skin, this, delaying wound healing.
I’m not saying you won’t get a result with dermal fillers, if you smoke, but this is why a smoker may not get the result, or lasting result, as a non-smoker would, with cosmetic injections.