Hello, Welcome to Healthcare Magic. I have read your question fully and understand your concerns. It is unclear from your question whether you have hypothyroidism or hyperthyroidism. TSH of 19 shows that you have hypothyroidism. Were you hyperthyroid first (with very low levels of TSH) and then became hypothyroid? Palpitations occur in hyperthyroidism. One of the side effects of Levothyroxine is nausea. It normally settles with a few weeks of starting the medicine. Sometimes if the tablet is taken wrongly it can also cause nausea. You should take the Levothyroxine tablet in the morning on an empty stomach. Take the tablet with lot of water. Wait for at least 45 min to 1 hour before you eat or drink anything (except water). Avoid fiber rich food for at least 4 hours after taking the Thyroid tablet. Similarly, do not take antacids, multi vitamins, iron supplements and other tablets with Levothyroxine. You need to wait at least 2-3 hours after taking the Levothyroxine. You could take a tablet like Domperidone 20 mg two-three times a day or Cyclizine 50 mg two-three times a day for 1 week and see if the nausea settles. If despite following the above suggestions the nausea continues, then you should see your doctor for a further evaluation. I do not think your nausea is from a neurological cause. I hope this answer has helped you. Thank you Regards Dr Sunita Sayammagaru