Saffron appears (from preliminary studies and anecdotal evidence) to increase serotonin. If you're already on something that increases serotonin, I'd just be alert for the standard signs of overdose while you ramp up, unexplained fevers and such. But I, for example, am on twice the "maximum" dose of mirtazepine and hit 100mg of saffron without any issues. So I don't think this is a contraindication, any more than any other 'helper' med is that you might take to increase the effect of your main med. Just keep an eye out.