I think one of the biggest reasons people lose balance is not dizziness ... it's that they haven't built their foundation from the ground up. They're up on their toes so the slightest little thing can make them fall over. Add a little dizziness or bumpy ground and you're all over the place. Try putting your heels on the ground, feeling all four corners of your right foot, all four corners of your left foot and all for corners of the box they create together. Keep your knees soft. (When they're not, it inhibits blood flow, which also creates dizziness.) When you find yourself on your toes, especially if you're feeling dizzy, put your heels down and soften your knees.

Turning comes naturally in hooping. Hoopers tend to turn using one of two methods -- the step-step-step method of taking small baby steps while walking in a circle or the method of planting one foot and either walking around it or spinning on the ball of it. In both cases, the ground is what grounds us. Balance begins in the ground! When we feel off balance, go to the ground. Bend the knees and put the heels down. Resist the urge to adjust from the top of the head down. This just throws us off balance more and generally makes one foot lose contact with the ground. Instead, put your heels down. Let your knees soften. Ground yourself by thinking from the ground up.

Dizziness is caused by sloshing around the fluids in the inner ear. You don't want to suddenly stop. That can make you pass out. Instead, slow your spin until you stop, then turn three circles the other direction. This will almost always set you right.

Ways to prevent dizziness -- 1) Focus on your hand or on your hoop while you're sustained spinning or keep a soft focus on the ground, 2) Keep the head level - do not let it flop around, which sloshes that inner ear fluid , 3) Keep your nasal passages clear - using a neti pot is great for this, 4) maintain a constant speed. Resist the urge to speed up.  5) slowly build your tolerance for spinning. Count your turns, then your minutes that you can turn. Build up to lots of turns while balanced between both your feet, 6) Make sure you've eaten a healthy meal. Sometimes low blood sugar leads to dizziness 7) Stay hydrated with water or electrolytes. Alcohol can also add to dizziness, 8) slow to a stop. Do not stop abruptly. This often makes people fall over. 

I have a tutorial called Some Pretty Turns I Love that talks a bit about turning and also about building your foundation from the ground up. You might want to check it out. Here's a link:http://www.youtube.com/watch?v=95vvIO93ggE

If none of this works for you and you continue to feel dizzy or you feel queasy after spinning, you may have an inner ear infection or other health issue. Get a doctor to check it out. Vertigo is also a problem for some hoopers.

If you have spun so much that you feel like you're going to puke, one of the most effective and almost instant treatments for nausea is tetrahydracanabinal, or THC, the active ingredient in marijuana. It remedies most nausea in about five minutes. When I worked at the National AIDS Hotline, we used to recommend it to AIDS patients who were having trouble keeping food down. I've also seen it help hoopers who were about to throw up after their first long session of sustained spinning. The queasiness doesn't happen immediately. It's usually 15-30 minutes later. With practice it goes away also, like dizziness, but there are ways to treat queasines so it doesn't ruin the whole rest of your day.

Spinning is something you can build up a tolerance for but don't push yourself. When you practice sustained spinning, it's important to keep the same speed (don't speed up and slow down), a soft focus on the ground or on the back of your hand or on your hoop, keep your head level (not looking up, then down), slow down instead of just stop, build your foundation from the ground up so you're not turning on your tip toes and, when you get to that place where you think, "Oh gosh! I feel like I might fall down!" remember to breathe and maintain your same speed keeping your head level and say to yourself, "This is just fear. If I keep going, this will pass." Which it will. Keep going. This fear holds us back more than the reality that we might fall. We often stop because we are afraid. Or, if we do fall, it's because we change our focus or just stop or move our head up or down or around from its original position. Those things we can recognize and avoid. Overcoming the fear of faling will help us sustained spin like sufis though. Once you get over that hurtle, you can spin and spin and spin...