Is extreme dizziness after Kybella a rare side effect?

For some people, the amount of swelling after deoxycholate (active ingredient of Kybella) can cause dizziness and lightheadedness, and even fainting, due to "third spacing."  This "third spacing" means enough of the water portion of the blood has left the blood circulatory system to go into the area of inflammation (in this case, where the fat cells have died) that the overall volume of blood is temporarily low, and the heart responds by beating faster and the blood pressure drops---especially when the person changes positions such as going from lying down to sitting up to standing up to walking/running.  This phenomenon is very uncommon (but not quite rare) in the first 2-3 days after Kybella to the fat under the chin. Then it dissipates, as the water in the neck area goes back into the circulatory system and the body (naturally) adds more volume to the blood via your water intake.

Please be sure you are adequately hydrating.