Tell your sister good luck. I have a very sensitive stomach, but yet vomitting is rare for me. I just feel like I'm going to a lot.
Like I said, this is no picnic but it works. If she starts to have problems drinking anything, tell her to just go slow. I find it easier to not gulp, as some people suggest. For me, I like to sip (with a straw as far back in my mouth as possible) until I HAVE to stop. Put candy in my mouth for a minute or two and then try again. It also helps if you have music on or watch a movie as you drink because it "sort of" gets your mind off of what you are doing. I do not recommend doing it with nothing going on around you. But have a bucket or trash can on hand...just in case you upchuck. Please stress to your sister to do this on a night and day where she has nothing to do and can stay close to a bathroom. I honestly think the worst hours of having to "go" are between 7pm and 11 am. After that, it is pretty much out of your system and you can go on with your life. Anyways, let me know how she does and also what you decide. If you choose to do a store bought one, please write and tell me all about how it is supposed to be done and if you start having results. Because even though I know this one really works, I am always searching for something that can be alot easier to swallow.
Take care.
