Emergen-C also has electrolytes, as well as Gatorade.
Taking any of the above works. I had severe food poisoning once, and I couldn't drink water. The nurse told me I had to get electrolytes into my system, so she told me to sip two quarts of Gatorade. I felt better after one bottle. Also, eat sweet potatoes, regular potatoes, and bananas. All of those are loaded with potassium, magnesium, and natural sodium.