There are two main reasons why you can still feel symptoms while taking thyroid medication.

1. You are not being given the right dosage. Many doctors are misdiagnosing people and either giving them too much or too little. Not having the right balance can cause you to have symptoms. This comes from using your lab ranges with your bloodwork instead of optimal ranges.
2. The second reason is because you are not treating the root cause of your thyroid issue. Medication is like a bandaid over the problem. It doesn’t actually fix the issue. So getting to the root cause is a must. If you want to learn the steps to get started check out the thyroid healing roadmap. 
3. One addition I like to add is some people’s bodies just don’t do well with certain medications. Something in the medication make them react. So that can be a issue as well. But usually it is because the first two reason.