Persistent lightheadedness (7 months) that feels like a concussion with minmal/no pain. gets worse standing up and better lying down. nausea. recent (1 wk) heart palpitations. taking zantac (ranitidine) 1 mth.

Lightheadedness: Many conditions can cause that but since you have heartburn you need to be checked for anemia which could be a result of GI bleed. Cardiac arrhythmia can also cause this condition. See your doctor ASAP

Get it checked. : should have a full physical examination including checking Blood pressures in lying and standing position , blood tests, EKG with Holter monitor and possibly imaging studies of the brain such as CT scan or MRI of the head,

Stop the meclizine: Check orthostatic heart rate and BP. Holter monitor 24 hour if palpitations re-occur. Check thyroid function. EKG only looks at a few seconds of electrical heart activity. Meclizine is used for motion sickness and can be used with caution for true vertigo. It can cause dizziness, sedation and confusion. See a neurologist if the problem persists.