Many things: The most frequent cause is mild dehydration. Other causes could included heart disease or rhythm disturbance, too man y medications, autonomic dysfunction and other issues. If drinking more water and less caffeine and alcohol doesn't fix this in a few days, or if you pass out you should see a doctor soon.
Answered 12/9/2015
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A doctor has provided 1 answer
A doctor has provided 1 answer
A doctor has provided 1 answer
A doctor has provided 1 answer
2 doctors weighed in across 2 answers
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