Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. You are having hypothyroidism which is the reason for swollen thyroid gland. That is why you are asked to take levothyroxin which is a thyroid hormone that is deficient in you. Since you have undergone biopsy and its negative, you don t have to worry about anything. Just take the tablets without fail as prescribed by your doctor. If you have problem swallowing then consult a surgeon who may do an endoscopy to see if there is any obstruction. But i feel it is mainly because of the enlarged thyroid gland which will eventually shrink in size with proper treatment. Certain medications, supplements and even some foods may affect your ability to absorb Levothyroxine. Talk to your doctor if you eat large amounts of soy products or a high-fiber diet or you take other medications, such as: i. Iron supplements or multivitamins that contain iron ii. Cholestyramine iii. Aluminum hydroxide, which is found in some antacids iv. Calcium supplements Regards- Dr Sanjay Kini