Brief Answer: visit ER, if possible Detailed Answer: Hi, Thanks for writing to us. Horney goat weed dilates the blood vessels and can lower blood pressure. As you are already on antihypertensive medication, its use could have decreased your blood pressure remarkably. As you are feeling dizzy, lightheaded, weak and cant sleep, it would be better that you visit a doctor so that your blood pressure can be recorded and if required ECG can be done. Usually we advise people with low BP to take adequate fluids and increase the salt intake. Also while sleeping, head end should be raised. During an episode of low BP one may take a glass of lemon water with added salt or may also take a properly constituted oral rehydration solution as it contains all the electrolytes. In your case, I would encourage you to visit emergency room of a nearby hospital as BP monitoring is required in your case. Regards.

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