I know that discussing artificial sweeteners is one touchy topic for many families, especially when PWS is involved and our choices are so limited. I want to write about our latest experience with Erin and Splenda, not to add fuel to the fire, but in case what we have seen rings a bell with anyone else. Some of us use artificial sweeteners w/o problem and others of us don't. I'm not giving direction to either group, just our experience with Erin.
In theory, using Splenda or others is ideal. The calories are low, and so is the cost (at least compared to things like xylitol). We've stayed away from all of them but decided to give it a try when we were going through a time when a situation arose when we needed to increase Erin's liquids dramatically. We tried to use a little Crystal Lite lemonade every day. I used the bottled kind and even diluted that. Within a few days, we saw major changes in behavior. She became irritable, inflexible, and all-around unpleasant. After a wash-out from the Crystal Light, she returned to herself again. This is not to say that she still doesn't have a flare from time to time, but the intensity and frequency of her meltdowns were markedly different. We won't try that again!
We have other options. We didn't have to even try Splenda, but the convenience and cost were appealing. What we saw from those days was that it was definitely NOT worth it for us. It may well be that only a subset of children with PWS are sensitive to this or that, but it might be worth considering if you are concerned about the type of issues we saw with Erin. Again, before anyone takes offense, I am not evaluating anyone else's decisions, just describing our experience in case it might benefit someone else.