Brief Answer: inadequate hydration Detailed Answer: Hello, Thank you for your question. I am sorry your daughter is not well. There is most likely a connection between your daughter's low blood pressure and her fainting episode today. The most common reason for low blood pressure in a child of this age is inadequate hydration. However, considering her medical history as you've reported it, there are other possibilities as well. One of which could be hormonal, for example her thyroid. For now until you're able to see your doctor, I would concentrate on her hydration as a means of trying to elevat her blood pressure and prevent further fainting. I think it is important that she be watched closely by you or someone you trust until you're able to consult with your doctor. I am concerned that she may faint and injure herself as she is falling. There are a lot of factors to figure out in order to arrive at the appropriate diagnosis, and prescribe the correct treatment plan. I am sure your doctor will be able to help you with this. Good luck.

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