Instead of switching sweeteners, it might be time to switch doctors. In the 100+ splenda studies that have been performed in the last 20 years, not ONE has ever linked splenda with urinary problems. Believe me, if it did cause urinary issues, there's no way it wouldn't have been detected during the testing phase.
You doctor is reaching- big time. I'm surprised he didn't blame your urinary pain/pressure on the alignment of the planets. That's how ridiculous blaming splenda for something like this is.
Is splenda perfectly safe for long term use? The jury's not in. Time will tell. But a direct link between splenda and urinary pressure/pain? That's absolutely ludicrous.
And recommending stevia as a substitute?!?! It sounds like your doctor might need to lay off the self medication.
There's a reason why stevia isn't approved for use in food (and it isn't some sugar lobby conspiracy). The reason is that there are numerous studies
that show potential links between steviosides (the sweet component that's extracted from stevia) and both decreased male virility and cancer. CANCER!
Stevia is popular with the holistic crowd because it's 'natural'. They erroneously equate 'natural' with 'safe.'
are all 'natural,' and yet not safe in the slightest. It's truly a twisted society we live in that something so potentially dangerous as stevia would be embraced as a sweetener simply because it's a plant.
Even if someone were to dispute Stevia's carcinogenic/reproductive impact (and some do), it is generally agreed that stevia decreases heart rate and blood pressure. Although on the outside these effects may be perceived as a good thing... it's proof that stevia is impacting physiology to a substantial degree. Do you really want to be altered to that extent (good or bad) by your sweetener?
And lastly, although less processed forms of stevia leaf are considered safer, they taste, across the board, vile. When you get into the more dangerous steviosides, some brands taste better than others, but even the best brand has a noticeable aftertaste (I've tasted all the best selling brands myself and confirmed this).
So, summing everything up:
Splenda- good tasting, approved by the FDA, with no studies proving health issues
Stevia- bad tasting, unapproved by the FDA, with studies proving potential long term health impact
Stick with splenda, get a new doctor.